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5i' SECTION 5 EQUIPMENT FOR THE MEASUREMENT OF DIGITAL AND ANALOGUE/DIGITAL PARAMETERS Recommendation O.131 QUANTIZING DISTORSION MEASURING EQUIPMENT USING A PSEUDO-RANDOM NOISE TEST SIGNAL (Geneva, 1976; amended at Geneva, 1980, and at Melbourne, 1988) 1 Preamble It is important that the characteristics of quantizing distor- tion measuring apparatus are specified with sufficient precision to ensure that all future designs of measuring apparatus conforming to the recommended specification shall be compatible with one another, i.e., they shall be capacble of interworking and give results of specified accuracy without the need for any special procedures or corrections to the measurements results. It is considered equally important that all designs of measuring apparatus conforming to the recommended specification shall be capable of interworking with existing designs of measuring apparatus already in use by various Administrations, who will thus not be placed at any economic disad- vantage. The following specification is based on the proposals stu- died by Study Group XVIII and is specifically aimed at the forego- ing compatibility objectives. Note - The question of interworking between existing designs of quantizing distortion measuring apparatus is not, in itself, directly relevant to this specification, but it is worth recording that this topic has been studied by the Federal Republic of Germany and the United Kingdom Post Office. Satisfactory rules have been established to facilitate interworking between the different exist- ing types of measuring apparatus which use a band-limited pseudo-random noise source. 2 Testing method proposed The method proposed is that described in Method 1 in S 9 of Recommendation G.712 [1]. The proposed noise source is band-limited pseudo-random noise having a probability density distribution of amplitudes which is substantially near to a Gaussian distribution The signal-to-total distortion power, including quantizing distortion, is measured as the ratio of the power of received stimulus in the reference band, to the noise power in the measured band. A correction is included to relate the measurement to the full PCM speech channel bandwidth The principle of the measurement is illustrated in Figure 1/O.131. Figure 1/O.131, p. 3 Basic specification clauses 3.1 Send The sending signal is a band-limited pseudo-random noise hav- ing the following characteristics: 3.1.1 Band limited noise stimulus Approximately Gaussian distribution of the amplitudes within the bandwidth of the send filter. The bandwidth can have any value from 100 Hz to 200 Hz between the 3-dB points (see SS 3.1.4 and 3.1.5 below). 3.1.2 Number of spectral lines Not less than 25 spectral lines with a spacing not greater _________________________ The receive measuring apparatus specified in S 3.2 may also be used to measure quantizing distortion using a sinusoidal test signal in the frequency range 350-550 Hz (preferably at 420 _ 20 Hz) instead of the pseudo-random noise stimulus. It should be noted, how- ever, that while the measurement is similar to Method 2 described in Recommendation G.712 [1], the obtained measurement results are related to a bandwidth of 3.1 kHz and that no noise weighting is provided. It should also be noted that results given by the pseudo-random noise and sinusoidal methods may not be the same. than 8 Hz measured at the output of the send filter. 3.1.3 Peak-to-r.m.s. ratio 10.5 dB. Tolerance _ | .5 dB. Note 1 - The requirements according to SS 3.1.1 to 3.1.3 above may be accomplished by a noise stimulus derived from the out- put of a 17-stage shift register with exclusive OR gating with the outputs of stages 3 and 17 returned to the input of stage 1. The shift register produces a maximally long sequence of (217 - 1) bits. The shift register is driven at a clock frequency fc Hz such that the spectral line spacing fs Hz of the output signal is less than or equal to 8 Hz. In order to meet the specified limits of the peak-to-r.m.s. ratio of the sent signal as given in S 3.1.3 above, the clock fre- quency can be adjusted to: fc = fs (217 - 1) Hz To keep the peak factor within the specified limits, a stabil- ity of the clock frequency fcon the order of 1% is required. Note 2 - Instead of using a shift register to generate the noise signal, other principles may be adopted as long as the gen- erated signal has the characteristics recommended in SS 3.1.1 and 3.1.3 above. 3.1.4 Frequency position of sent signal Between 350 and 550 Hz. 3.1.5 Sending filter characteristics The attenuation of the bandpass filter with reference to minimum attenuations should be as follows: not lower than 350 Hz 3 dB point at lower frequency not exceeding 550 Hz 3 dB point at upper frequency below 250 Hz greater than 55 dB at 300 Hz greater than 20 dB at 580 Hz greater than 6 dB at 650 Hz greater than 20 dB at 700 Hz greater than 40 dB at 750 Hz greater than 50 dB at and above 800 Hz greater than 60 dB The response characteristic of a filter designed to these lim- its should give a bandwidth between 3-dB points of at least 100 Hz. The performance requirements for the sending filter charac- teristics conforming to the above limits is given in Figure 2/O.131. 3.1.6 Sending reference level range 0 dBm0 to at least -55 dBm0 for relative levels according to Recommendation G.232, S 11 [2] with a setting accuracy of _ | .5 dB. 3.1.7 Output impedance | frequency range 300 Hz to 4 kHz) - Balanced, earth free (other impedances optional) 600 ohms - Return loss _" 30 dB - Output signal balance _" 40 dB 3.2 Receive 3.2.1 Receive reference filter Nominal bandwidth of reference path 350-550 Hz. (See Note below). The characteristic of the filter is chosen to prevent inaccu- racy in the measurement of the received noise stimulus in the pres- ence of quantizing distortion and other system noise conditions. The filter should not diminish the power of a noise band between 350 Hz and 550 Hz by more than 0.25 dB. Figure 2/O.131, p. Note - The receive reference filter ideally restricts the bandwidth of the reference path to respond only to the spectrum of the received noise stimulus. However, the bandwidth of 350-550 Hz is chosen to allow for the need to interwork with test apparatus having a noise source bandwidth of up to 200 Hz. 3.2.2 Bandwidth of measuring path At least 2.4 kHz (with a loss variation of less than 2 dB). The required bandpass characteristic of the filters for measurement of distortion products is indicated below and is such that received noise stimulus does not affect measurements. Attenuation with reference to the minimum attenuation: 150 Hz and below greater than 60 dB 650 Hz greater than 55 dB 700 Hz greater than 35 dB 750 Hz greater than 20 dB 800 Hz 3 dB or greater 3.4 kHz 3 dB or greater 3.5 kHz greater than 10 dB 3.6 kHz greater than 20 dB 3.7 kHz greater than 40 dB 3.75 kHz greater than 50 dB 5.0 kHz and above greater than 60 dB The performance requirements for the measurement filter characteristic conforming to the above limits is given in Figure 3/O.131. Figure 3/O.131, p. 3.2.3 Bandwidth correction The calibration of the test apparatus shall include a correc- tion factor of appropriate value to relate the signal to total dis- tortion power measured to the total distortion power present in the full PCM channel bandwidth of 3100 Hz. The correction factor is given by the following expression, which assumes a uniform distri- bution of distortion power over the channel bandwidth: 10 log 10 fIy ___ (dB) where y | s the effective noise bandwidth of the measuring filter in Hz. 3.2.4 Input impedance - Balanced, earth free (other impedances optional) 600 ohms - Return loss _" 30 dB - Input longitudinal interference loss (below 4 kHz) _" 46 dB - Input longitudinal interference loss (at 40 Hz) _" 60 dB 3.2.5 Input reference level range 0 dBm0 to at least -55 dBm0 for relative levels according to Recommendation G.232 [2]. 3.2.6 Accuracy of the signal-to-total distortion ratio indication For reference levels in the range -6 dBm0 to -55 dBm0 and an absolute distortion signal not less than -72 dBm0: - Measuring range 10 dB to 40 dB: Accuracy _ | .5 dB. - Measuring range 0 dB to 10 dB: Accuracy _ | .0 dB. For reference levels in the range 0 dBm0 to -6 dBm0: - Measuring range 20 dB to 40 dB: Accuracy _ | .5 dB. - Measuring range 0 dB to 20 dB: Accuracy _ | .0 dB. Note 1 - These limits include the inaccuracies which are caused by: - the effective bandwidth of the measuring filter, - the receive reference filter, - the attenuator in the measuring path, - the characteristics of the indicating circuit. Note 2 - For reference level ranges 0 dBm0 to -6 dBm0, the wider tolerances are not only required by the measuring apparatus but reflect also the characteristics of PCM coders and decoders when operated near the overload point. 4 Operating environment The electrical performance requirements shall be met when operating at the climatic conditions as specified in Recommendation O.3, S 2.1. References [1] CCITT Recommendation Performance characteristics of PCM channels between 4-wire interfaces at voice frequencies , Vol. III, Rec. G.712. [2] CCITT Recommendation 12-channel terminal equipments , Vol. III, Rec. G.232. Recommendation O.132 QUANTIZING DISTORTION MEASURING EQUIPMENT USING A SINUSOIDAL TEST SIGNAL (Geneva, 1980; amended at Melbourne, 1988) 1 Introduction This specification gives basic clauses describing the essen- tial features to be provided in test equipment using a sinusoidal test signal for quantizing distortion measurements on PCM channels important that the characteristics of quantizing distortion measur- ing apparatus of this type are sufficiently specified to ensure that they are capable of interworking and that they will give results of sufficient accuracy. This specification is based on a general statement of the method described as Method 2 in S 9 of Recommendation G.712 [1]. 2 Testing method The testing method consists of applying a sine-wave signal to the input port of a PCM channel and measuring the ratio of the received signal to distortion power, using the proper noise weight- ing (see S 3.3.4 below). The method also requires the use of a narrow-band rejection filter in the receiver equipment to block the sinusoidal test signal from the distortion measuring circuits so that the distortion power may be measured. 3 Specifications 3.1 Test signal frequencies A test signal in either of two frequency bands may be required depending on the test-signal rejection filter being used to make the measurement. The preferred test frequencies are either 820 Hz or 1020 Hz. However, other frequencies in the rejection band of the test-signal rejection filter (such as 804 Hz or 850 Hz) may be used. 3.2 Characteristics of the signal source 3.2.1 Signal level range At least -45 to +5 dBm0 for relative levels according to S 11 of Recommendation G.232 [2] with a setting accuracy of _ | .2 dB. 3.2.2 Output impedance | frequency range 300 Hz to 4 kHz) - Balanced, earth free (other impedances optional) 600 ohms - Return loss _" 30 dB - Output signal balance _" 40 dB 3.2.3 Distortion and spurious modulation ratio _" | 0 dB 3.2.4 Frequency accuracy and stability The accuracy and stability of the test signal frequency shall be appropriate to the frequency used and its position with respect to the rejection band of the filter concerned. The accuracy and stability must in any case be such that the frequency is never a submultiple of the PCM sampling rate. 3.3 Characteristics of the measuring instrument 3.3.1 Measuring range and accuracy 10 to 40 dB signal-to-distortion ratio with an accuracy of _ | .0 dB. 3.3.2 Input signal range At least -55 to +5 dBm0 for relative levels according to S 11 of Recommendation G.232 [2]. 3.3.3 Input impedance | frequency range 300 Hz to 4 kHz) - Balanced, earth free (other impedances optional) 600 ohms - Return loss _" 30 dB - Input longitudinal interference loss (below 4 kHz) _" 46 dB - Input longitudinal interference loss (at 40 Hz) _" 60 dB 3.3.4 Measuring filter The value of the distortion signal shall be weighted by the standard CCITT noise weighting filter for telephony (see Recommen- dation O.41). Alternatively, C-message weighting may be used (see Annex A to Recommendation O.41). A calibration correction factor may be necessary when C-message weighting is used. The manufactur- ing tolerances on the characteristics of these filters may have to be less than is permitted in their respective specifications, in order to achieve the measuring accuracy in S 3.3.1. 3.3.5 Test-signal reject filter Either of two test-signal rejection filters may be provided, with characteristics as given in Table 1/O.132. H.T. [T1.132] TABLE 1/O.132 Test-signal reject filter characteristics ___________________________________________________________________ { 804 to 850 Hz test-signal reject filter } ___________________________________________________________________ Frequency Loss ___________________________________________________________________ < 325 Hz < 0.5 dB < 570 Hz < 1.0 dB < 690 Hz < 3.0 dB 800 to 855 Hz > 50 dB (rejection band) > 1000 Hz < 3.0 dB > 1105 Hz < 1.0 dB > 1360 Hz | | | | | | | | | | < 0.5 dB ___________________________________________________________________ { 100 to 1020 Hz test-signal reject filter } ___________________________________________________________________ Frequency Loss ___________________________________________________________________ < 400 Hz < 0.5 dB < 700 Hz < 1.0 dB < 860 Hz < 3.0 dB 1000 to 1025 Hz > 50 dB (rejection band) > 1180 Hz < 3.0 dB > 1330 Hz < 1.0 dB > 1700 Hz < 0.5 dB ___________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Table 1/O.132 [T1.132], p. 3.3.6 Detector characteristics An r.m.s. or quasi-r.m.s. detector having sufficient accuracy to meet the accuracy objective must be used for measuring the dis- tortion signal. 3.3.7 Bandwidth correction The calibration of the measuring instrument shall include a correction factor of appropriate value to account for the loss in effective noise bandwidth due to the test-signal reject filter. The correction factor assumes a uniform distribution of distortion power over the frequency range involved and is of the following form: Correction (dB) = 10 log 10 ffective bandwidth of the measuring instrument ______________________________________________ 4 Operating environment The electrical performance requirements shall be met when operating at the climatic conditions as specified in Recommendation O.3, S 2.1. References [1] CCITT Recommendation Performance characteristics of PCM channels between 4-wire interfaces at voice frequencies , Vol. III, Rec. G.712. [2] CCITT Recommendation 12-channel terminal equipments , Vol. III, Rec. G.232. Recommendation O.133 EQUIPMENT FOR MEASURING THE PERFORMANCE OF PCM ENCODERS AND DECODERS (Geneva, 1984; amended at Melbourne, 1988) 1 Introduction 1.1 Encoders and decoders conforming to Recommendation G.711 [1] for converting voice-frequency signals to digital (PCM) signals and vice versa are contained in various equipments described by relevant CCITT Recommendations. Examples of these equipments are: - PCM multiplexers (Recommendations G.732 [2] and G.733 [3]); - transmultiplexers (Recommendations G.793 [4] and G.794 [5]); - subsystems of digital exchanges (e.g., Recommendation Q.517 [6]). To ensure that the overall performance limits specified in the CCITT Recommendations are always met where the PCM equipments are interconnected, it is necessary to separately specify and measure the analogue-digital (A-D) and digital-analogue (D-A) performance of the equipments. In addition, analogue-analogue (A-A) and digital-digital (D-D) measurements have to be carried out. 1.2 The measuring instrumentation described below allows these measurements to be made on PCM equipments operating at 2048 kbit/s and/or 1544 kbit/s as specified in Recommendations G.732 [2], G.733 [3], G.793 [4], G.794 [5] and relevant Series Q Recommenda- tions. 2 General 2.1 Measuring functions and physical configuration The instrumentation described in this Recommendation consists of the following functional units. 2.1.1 An analogue signal generator to apply voice-frequency signals to the analogue input ports of the equipment under test. 2.1.2 An analogue signal analyzer to process voice-frequency signals received from the analogue output ports of the equipment under test. 2.1.3 A digital signal generator to apply test signals to the digital input ports of the equipment under test. 2.1.4 A digital signal analyzer to process signals received from the digital output ports of the equipment under test. 2.1.5 The four units mentioned in SS 2.1.1 to 2.1.4 may be provided in any convenient physical arrangement as determined by the supplier. 2.1.6 The functions described in SS 2.1.3 and 2.1.4 may be realized using either conventional analogue-to-digital and digital-to-analogue conversion techniques, or by direct digital processing techniques. 2.2 Measuring accuracy and compatibility objectives 2.2.1 As a general objective, the accuracy of the measuring instrumentation should be an order of magnitude better than the relevant performance limits of the equipment under test. Due to technical and cost limitations, however, it may not always be pos- sible to meet this objective. 2.2.2 In addition errors may increase if instrumentation of different design is interworking or if the input and output parts of the equipment under test are not accessible at the same location (end-to-end measurements). 2.2.3 Where the test methods of Recommendations such as O.131 or O.132 are referenced below, it should be noted that some of the design requirements of such Recommendations may be insufficient to guarantee the accuracy called for in this Recommendation. Even when observing the specifications of this and other relevant Recommenda- tions (e.g. O.131, O.132), compatibility problems may arise espe- cially when pseudorandom noise signals are used as stimuli leading to reduced measuring accuracy and/or fluctuating results indica- tions. 2.2.4 In order to facilitate interworking of instrumentation of different design, it is recommended to provide pseudorandom noise signals having a specified periodicity (see SS 3.2.3.1 and 3.4.2.1). 2.3 Measurement capabilities Table 1/O.133 contains a list of parameters which can be meas- ured on the various equipments. In addition, the required measuring configuration is indicated. It should be noted, however, that not all the listed parameters can be measured with the instrumentation specified in this Recommendation. Where applicable, reference is made to other pertinent Recommendations. 3 Instrument specifications In this section the minimum requirements to be met by the four functional units of the instrumentation are described. The measur- ing accuracy is covered in S 4 below. 3.1 Interfaces 3.1.1 Analogue interfaces 3.1.1.1 Output and input impedances, balanced earth free: 600 and/or 900 ohms. 3.1.1.2 Return loss from 200 Hz to 4 kHz: _" | 6 dB. 3.1.1.3 Logitudinal conversion loss (frequency range 200 Hz to 4 kHz): _" | 6 dB. _________________________ Measurements at complex impedances are under study. H.T. [T1.133] TABLE 1/O.133 Measurement capabilities _____________________________________________________________________________________________________________ Measuring configuration Parameter A-D D-A A-A D-D Measurement facility _____________________________________________________________________________________________________________ { Gain (relationship between encoding law and audio level) } + + + + | ua) E _____________________________________________________________________________________________________________ { Variation of gain (loss) with time | ub) } + + + + E _____________________________________________________________________________________________________________ { Return loss (at voice-frequency ports) } + + + - O _____________________________________________________________________________________________________________ Longitudinal balance + + + - O _____________________________________________________________________________________________________________ { Attenuation/frequency distortion } + + + + E _____________________________________________________________________________________________________________ Weighted noise + + + + E _____________________________________________________________________________________________________________ { Discrimination against out-of-band input signals } __" __" __" __" O _____________________________________________________________________________________________________________ { Spurious out-of-band output signals } __" __" __" __" O _____________________________________________________________________________________________________________ Single frequency noise __" __" __" __" O _____________________________________________________________________________________________________________ { Total distortion (including quantizing distortion) } + + + + E _____________________________________________________________________________________________________________ { Variation of gain with input level } + + + + E _____________________________________________________________________________________________________________ { Crosstalk (measured with sinewave signals) | ua) } + + + + E _____________________________________________________________________________________________________________ { Crosstalk (measured with conventional telephone signal) } __" __" + __" O _____________________________________________________________________________________________________________ { Interference from signalling | uc) } O _____________________________________________________________________________________________________________ { Frequency of repetitive signal } + + + + 0 _____________________________________________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | a) Measurement to be performed while injecting an auxiliary signal in the disturbed channel. b) This parameter is called "stability" in Recommendations G.712 [9], G.714 [12] and G.792 [13]. c) Stimulus for signalling channel is not specified. E Essential __" Capability not provided O Optional + Yes - Not applicable Note - Where no symbol is shown, the need for the measurement is under study. Tableau 1/O.133 [T1.133], p. 5 3.1.2 Digital interfaces 3.1.2.1 Level conditions and frame format The instrumentation is required to operate satisfactorily with interface levels in accordance with Recommendation G.703 [7]. One or both of the following conditions of interface and frame formats, including extended frame formats and cyclic redundancy check (CRC) procedures, shall be provided: At 1544 kbit/s Recommendation G.703 [7], S 2, and Recommendations G.733 [3] and G.704 [11]. At 2048 kbit/s Recommendation G.703 [7], S 6, and Recommendations G.732 [2] and G.704 [11]. Additionally the digital analyzer is required to operate satisfactorily when connected via a length of cable which has an insertion loss of 6 dB at the half bit rate of the signal. The insertion loss of the cable at other frequencies will be propor- tional to \| _____ fIf | . In addition to providing for terminated measurements the instrumentation may also be required to monitor at protected test points on digital equipment. Therefore a high impedance and/or additional gain should be provided to compensate for the loss at monitoring points already provided on some equipments. 3.1.2.2 Impedances of digital interfaces The impedances at the digital outputs and inputs shall conform to Recommendation G.703 [7], SS 2 or 6. The return loss measured against the nominal impedance shall be: - 1544 kbit/s (with pre-emphasis) frequency range 20 kHz to 1.6 MHz at the input: _" | 0 dB frequency range 20 kHz to 500 kHz at the output: _" | 4 dB frequency range 500 kHz to 1.6 MHz at the output: _" | 6 dB - 1544 kbit/s (without emphasis) frequency range 20 kHz to 1.6 MHz at both input and output: _" | 0 dB - 2048 kbit/s frequency range 40 kHz to 2.5 MHz at both input and output: _" | 0 dB 3.1.2.3 Longitudinal conversion loss (Under study.) 3.2 Analogue signal generator The following minimum functions shall be provided: 3.2.1 Relative levels See Recommendation G.232 [8]. 3.2.1.1 Relative levels (minimum range): -16 dBr to 0 dBr. 3.2.2 Sinusoidal test signals 3.2.2.1 At levels of 0 and -10 dBm0, the generator shall pro- duce test signals in the frequency range 200 to 3600 Hz. The fre- quencies of S 3.2.2.2 below, comprising the reference and break points of the relevant masks, shall be provided as a minimum. See S 4.1.4 for a note on the choice of test frequencies. 3.2.2.2 Test signal frequencies (approximately): 200, 300, 420, 500, 600, 820, 1020, 2400, 2800, 3000, 3400 and 3600 Hz. 3.2.2.3 Deviation of transmitted frequency from indicated fre- quency: _ | Hz _ | .1%. 3.2.2.4 For at least one frequency (preferably approximately 820 or 1020 Hz), it shall be possible to adjust the level of the signal between +3 dBm0 and -55 dBm0. The levels of S 3.2.2.5 comprising the reference and break points of the relevant masks shall be provided as a minimum. See S 4.1.4 for a note on the choice of test frequencies. 3.2.2.5 Test signal levels: -55, -50, -45, -40, -30, -20, -10, 0 +3 dBm0. 3.2.2.6 Deviation of transmitted level from indicated level over the operating range of the instrument: _ | .2 dB. Means shall nevertheless be provided to make relative measurements as defined in S 4.2 within the specified tolerances. Note - This tolerance is specified to facilitate interwork- ing. Deviations in measurement results due to errors in test levels must be considered when reading the measuring accuracies quoted in this Recommendation. 3.2.2.7 Total distortion referred to a measurement bandwidth of 20 kHz is to be at least 20 dB better than the limits given in the diagram of Figure 4/G.712 [9]. 3.2.3 Pseudorandom test signal 3.2.3.1 A pseudorandom test signal in accordance with Recommendation O.131 shall be provided. To facilitate interworking, the sequence repetition rate (period) shall be fixed at 256 ms (2048 samples) derived, where possible, from the sampling rate of the encoder under test. Otherwise, the tolerance shall be _ | ms. Note - This requirement is also met by a period of 128 _ 0.5 ms (1024 samples). 3.2.3.2 The level of the pseudorandom test signal shall be adjustable between -3 dBm0 and -55 dBm0. The levels of S 3.2.3.3 below, comprising the reference and break points of the relevant masks, shall be provided as a minimum. 3.2.3.3 Test signal levels: -55, -50, -40, -34, -27, -10, -6, -3 dBm0. 3.2.4 Auxiliary signal 3.2.4.1 In order to increase the accuracy when performing crosstalk measurements, an auxiliary (activating) signal for injec- tion into the disturbed channel shall be provided. 3.2.4.2 Band-limited noise located between 350 and 550 Hz similar to that specified in Recommendation O.131, and having a level in the range -50 to -60 dBm0, may be used as an auxiliary signal. At frequencies below 250 Hz and in the range 700 Hz to 4 kHz, the spurious signal shall be at least 40 dB smaller than the auxiliary signal. 3.2.4.3 As an alternative, a sinusoidal signal having a level in the range -33 to -40 dBm0 may be employed. Harmonic components of the sinusoidal signal shall be at least 40 dB below the funda- mental. 3.3 Analogue signal analyzer The following minimum functions shall be provided. 3.3.1 Relative levels (See Recommendation G.232 [8].) 3.3.1.1 Relative levels (minimum range): -5 dBr to +7 dBr. 3.3.2 Level 3.3.2.1 Level measuring range: -60 to +5 dBm0. 3.3.3 Return loss | optional) 3.3.3.1 Return loss measuring range: 0 to 40 dB over the fre- quency range 200 to 3600 Hz. 3.3.4 Longitudinal balance in accordance with Recommenda- tion O.121 | optional) 3.3.4.1 Longitudinal conversion loss measuring range: 5 to 56 dB, over the frequency range 200 to 3600 Hz. 3.3.4.2 Longitudinal conversion transfer loss measuring range: 5 to 56 dB, over the frequency range 200 to 3600 Hz. 3.3.5 Weighted noise in accordance with Recommendation O.41 3.3.5.1 Noise measuring range: -80 to -20 dBm0p. 3.3.6 Total distortion in accordance with Recommendations O.131 and/or O.132 Note - To facilitate interworking, the observation time for Recommendation O.131 shall be 256 ms or a multiple thereof, derived, where possible, from the sample rate of the decoder under test. Otherwise the tolerance shall be _ | ms. 3.3.6.1 Total distortion measuring range: 0 to 40 dB. 3.3.7 Crosstalk 3.3.7.1 Level measuring range: -75 to -20 dBm0. 3.3.8 Frequency of a repetitive signal As an option it shall be possible to measure and display the frequency of any repetitive signal in the frequency range 200 and 4000 Hz applied to the input of the instrument at any level in the range defined in S 3.3.2. The result shall be displayed to a reso- lution of 1 Hz. The measurement shall be made to an accuracy of at least 50x10DlF2616. 3.4 Digital signal generator The following facilities shall be provided by the digital sig- nal generator. 3.4.1 Digitally encoded sine wave signals 3.4.1.1 At levels of 0 and -10 dBm0, digitally encoded sine waves with frequencies in the range 200 Hz to 3600 Hz are to be provided. The frequencies of S 3.4.1.2 comprising the reference and break points of the relevant masks, shall be provided as a minimum. See S 4.1.4 for a note on the choice of test frequencies. 3.4.1.2 Test signal frequencies (approximately): 200, 300, 420, 500, 600, 820, 1020, 2400, 2800, 3000, 3400 and 3600 Hz. 3.4.1.3 Deviation of transmitted frequency from indicated fre- quency: _ | Hz _ | .1%. 3.4.1.4 For at least one frequency (preferably approximately 820 or 1020 Hz), it shall be possible to adjust the level of the signal between +3 dBm0 and -55 dBm0. The levels of S 3.4.1.5 below, comprising the reference and break points of the relevant masks, shall be provided as a minimum. See S 4.1.4 for a note on the choice of test frequencies. 3.4.1.5 Test signal levels: -55, -50, -45, -40, -30, -20, -10, 0, +3 dBm0. 3.4.1.6 Deviation of transmitted level from indicated level: _ | .2 dB. Note - This tolerance is specified to facilitate interwork- ing. Deviations in measurement results due to errors in test levels should be included in measuring accuracy specifications. 3.4.1.7 Digital reference sequence The digital signal generator shall be capable of generating the periodic sequences of character signals detailed in Table 5/G.711 [1] and/or Table 6/G.711 [1], equivalent to a 1 kHz sine wave at a nominal level of 0 dBm0. 3.4.2 Digitally encoded pseudorandom noise signal 3.4.2.1 The noise source shall have the same characteristics, in terms of frequency spectrum and amplitude distribution, as a signal that would result from applying a band-limited pseudorandom noise source , conforming to Recommendation O.131, to a perfect transmit channel be fixed at 256 _ | ms (2048 samples). Note - This requirement is also met by a period of 128 _ 0.5 ms (1024 samples). 3.4.2.2 The level of the digitally encoded pseudorandom noise signal shall be adjustable between -3 dBm0 and -55 dBm0. The levels of S 3.4.2.3 below, comprising the reference and break points of the relevant masks, shall be provided as a minimum. 3.4.2.3 Test signal levels: -55, -50, -40, -34, -27, -10, -6, -3 dBm0. 3.4.3 Additional digital signals In addition to the signals specified in SS 3.4.1 and 3.4.2, it shall be possible to manually select any 8-bit repetitive pattern. 3.4.4 Time slot assignment 3.4.4.1 It shall be possible to apply the signals described in SS 3.4.1, 3.4.2 and 3.4.3 to: a) any selected speech time slot, b) as an option, to all speech time slots. Speech time slots not containing the signals described in SS 3.4.1 and 3.4.2 shall be provided with the digital signals of S 3.4.3. 3.4.4.2 As an option, an interface shall be provided to enable an externally generated digital signal to be applied to any selected speech time slot. The interface shall meet the require- ments of a co-directional interface as defined in Recommendation G.703 [7]. 3.4.5 Test of PCM multiplex alarm unit 3.4.5.1 2048 kbit/s PCM multiplexers | (e.g. Recommendation G.732 [2]) 3.4.5.1.1 It shall be possible to modify any bit of the digi- tal signal in time slot 0 of the frames containing the frame align- ment signal and of the frames not containing the frame alignment signal in order to fully test the multiplex alarm unit 3.4.5.1.2 It shall be possible to modify any bit of the digi- tal signal in time slot 16 of frame 0. 3.4.5.1.3 As an option during the tests described in SS 3.4.5.1.1 and 3.4.5.1.2, a digitally encoded sine wave signal of approximately 820 Hz at a level of 0 dBm0 shall be applied to all speech time slots. This is to provide a means of checking speech highway suppression when the multiplex alarm unit operates. 3.4.5.1.4 As an option it shall be possible to modify any bit of the digital signal in time slot 16 of frames 1 to 15 of a mul- tiframe when channel associated signalling is in use. All 30 sig- nalling channels may be provided with the same pattern. 3.4.5.1.5 The instrument shall be capable of generating frame formats including CRC multiframes and CRC check bits, in accordance with Recommendation G.704, S 2.3 [11]. 3.4.5.1.6 Where a CRC multiframe is being generated, it shall be possible to modify any bit of the CRC multiframe alignment sig- nal. 3.4.5.1.7 As an option, an interface shall be provided to allow the signalling bits associated with any selected speech time slot to be controlled from an external source when channel associ- ated signalling is in use. 3.4.5.2 1544 kbit/s PCM multiplexes | e.g. Recommendation G.733 [3]) 3.4.5.2.1 The instrument shall be capable of generating frame formats including CRC multiframes, in accordance with Recommendation G.704, S 3.1 [11]. 3.4.5.2.2 It shall be possible to modify the first bit of each frame containing the frame alignment signal. 3.4.5.2.3 It shall be possible to modify the first bit of frame 12. 3.4.5.2.4 Where the 12-frame multiframe is being generated, it shall be possible to modify the eighth bit of each channel time slot in frames 6 and 12 when channel associated signalling is in use. All signalling channels may be provided with the same pattern. 3.4.5.2.5 Where the 24-frame multiframe is being generated, it shall be possible to modify the eighth bit of each channel time slot in frame 6, 12, 18 and 24 when channel associated signalling is in use. All signalling channels may be provided with the same pattern. 3.4.5.2.6 As an option, an interface shall be provided to allow the signalling bits associated with any selected speech time slot to be controlled from an external source when channel associ- ated signalling is in use. 3.4.6 Selectable synchronization It shall be possible to either: a) lock the digital generator clock rate to that at the input of the digital analyzer, or b) allow the generator and analyzer clocks to free run within the overall allowed frequency tolerances, c) as an option, lock the digital generator clock rate to an external clock. 3.5 Digital signal analyzer The digital signal analyzer shall be capable of measuring the following parameters by extracting the digital signal from any selectable time slot of the PCM multiplex stream, and treating it, where appropriate, as an encoded audio signal. 3.5.1 Level 3.5.1.1 Level measuring range: -60 to +5 dBm0. 3.5.2 Weighted noise in accordance with Recommendation O.41 3.5.2.1 Noise measuring range: -80 to -20 dBm0p. Note - If the digital analyzer is receiving a digital signal corresponding to the decoder output value number 1 for the A-law or decoder output value number 0 for the u-law and the polarity bit is kept in a fixed position, the indicated noise level shall not exceed -85 dBm0p. 3.5.3 Total distortion in accordance with Recommendations O.131 and/or O.132 Note - To facilitate interworking, the observation time for Recommendation O.131 shall be 256 ms or a multiple thereof, derived, where possible, from the sample rate of the encoder under test. Otherwise the tolerance shall be _ | ms. 3.5.3.1 Total distortion measuring range: 0 to 40 dB. 3.5.4 Crosstalk 3.5.4.1 Level measuring range: -75 to -20 dBm0. 3.5.5 Peak code detection and display It shall be possible to display the positive and/or negative peak code present in an observation period of at least 800 frames, or in automatically selected repetitive periods of at least 800 frames. This code may have any integer value in the range 0 to _ | 27. As an alternative option the peak code can be indicated by a display of the equivalent tone level in dBm0. 3.5.6 Signalling bits 3.5.6.1 As an option, the signalling bits associated with any speech time slot shall be selectable for display when channel asso- ciated signalling is in use. 3.5.6.2 An an option, an interface shall be provided to enable the signalling bits associated with any selectable speech time slot to be monitored by an externally connected instrument when channel associated signalling is in use. 3.5.7 Alarm detection and display (optional) The digital analyzer shall be capable of monitoring the digi- tal output of a PCM multiplex and recognizing and displaying the following alarm conditions and bit states. 3.5.7.1 PCM multiplex to Recommendation G.732 [2]: loss of signal, loss of frame alignment, loss of multiframe alignment where channel associated signalling is in use, loss of CRC multiframe alignment, state of bit 1 of time slot 0 of frame containing frame alignment signal, state of bits 1 and 3 to 8 of time slot 0 of frame not containing frame alignment signal, state of bit 6 of time slot 16 of frame 0, and display of information conveyed via the CRC procedure as defined in Recommendation G.704 [11]. 3.5.7.2 PCM multiplex to Recommendation G.733 [3]. 3.5.7.2.1 Loss of signal, loss of frame alignment, loss of multiframe alignment when channel associated signalling is in use. 3.5.7.2.2 When a 12-frame multiframe is being monitored, the state of bit 8 of each channel in the 6th and 12th frames and the state of bit 1 of the 12th frame. 3.5.7.2.3 When a 24-frame multiframe is being monitored, the state of bit 8 of each channel in the 6th, 12th, 18th and 24th frames, the state of bit 1 of the 12th frame, and the display of information conveyed via the CRC procedure as defined in Recommendation G.704 [11]. 3.5.8 Frequency of a repetitive signal As an option, it shall be possible to measure and display the frequency of any repetitive signal in the frequency range 200 Hz to 4000 Hz applied at a level in the range defined in S 3.5.1. The result shall be displayed to a resolution of 1 Hz. The measurement shall be made to an accuracy of at least 50 | (mu | 0DlF2616. 3.5.9 External speech time-slot interface As an option, an interface shall be provided to enable the digital signal contained in a selected speech time slot to be extracted and applied to a separate instrument. The interface shall meet the requirements of a co-directional interface as defined in Recommendation G.703 [7]. 4 Measuring accuracy 4.1 Definition of the error limits of the measuring instrumentation 4.1.1 The error limits stated in this Recommendation refer always to a complete measuring configuration and therefore include errors of the generator as well as of the analyzer side (if appli- cable). See Annex A to this Recommendation concerning the intrinsic errors in the PCM encoding process which may affect the interpreta- tion of measured results. 4.1.2 Even ideal encoder/decoder pairs conforming to the require- ments of Recommendation G.711 [1] exhibit intrinsic limitations to the PCM process which cannot be avoided of gain with input level and limited audio frequency range. The measuring instrumentation described here has the same gen- eral characteristics and limitations as an ideal encoder/decoder conforming to Recommendation G.711 [1]. For the purposes of this Recommendation the differences between an ideal encoder/decoder conforming to Recommendation G.711 [1] and the measuring instrument are defined as measuring errors. Figure 1/O.133 illustrates the relationship of these errors to the errors exhibited by the digital signal generator and digital signal analyzer. 4.1.3 When stating the total measuring error, the errors con- tributed by the analogue analyzer (EA\dA) and the analogue genera- tor (EA\dG) must also be considered. Because of the limited level accuracy of the analogue signal generator, variations in measure- ment result will arise due to quantizing gain effects in the PCM channel under test The total measuring error applicable to the four measuring configurations can be calculated as shown in Table 2/O.133. Figure 1/O.133, p. H.T. [T2.133] ___________________________________________________________ TABLE 2/O.133 { Definition of total measuring error } Measuring configuration Total measuring error ___________________________________________________________ A-D E + E D-A E + E A-A E + E D-D E + E ___________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Table 2/O.133 [T2.133], p. 4.1.4 Choice of test frequencies When specifying the accuracy of measurements on sinusoidal signals, the tone presented to the ideal encoder in Figure 1/O.133 is assumed to have a frequency unrelated to the sampling rate, and the measurement time is assumed to be long enough to eliminate averaging error. Intrinsic errors in tone measurements depend on the highest common factor of the test signal frequency and the PCM sampling rate. Simple submultiples of the sampling rate, and their harmon- ics, should be avoided. The instrumentation should use a large number of independent samples and the measuring accuracy should be specified relative to a minimum number of samples. A figure of at least 400 is recommended. Restrictions on the use of other frequen- cies should be stated. The choice of test frequency shall be made in accordance with Recommendation O.6. 4.1.5 Intrinsic distortion of test signals To facilitate interworking on total distortion measurements, certain variable-level, digitally-encoded signals, if provided, should be specified for intrinsic total distortion over the range of selectable levels, measured as follows: - Pseudorandom noise, sinusoidal signal, 420 Hz: by the method of Recommendation O.131. - Sinusoidal signal, 820 Hz or 1020 Hz: by the method of Recommendation O.132. 4.1.6 Measurement bandwidth for tone measurements The design of filters for tone measurements is not specified. However, measurement errors should be calculated relative to the results obtained by ideal selective measurement. 4.2 Summary of total measuring errors Full 8-bit coding is assumed as specified in Recommendation G.711 [1]. 4.2.1 Gain (relationship between encoding law and audio level) See Table 3/O.133. H.T. [T3.133] TABLE 3/O.133 ________________________________________________________________________________________________________ Error limits (dB) Parameter A-D D-A A-A D-D ________________________________________________________________________________________________________ { Gain (relationship between encoding law and audio level) | ua) } _ | .08 _ | .08 _ | .05 _ | .05 ________________________________________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | a) Measured at one frequency, approximately 820 Hz or 1020 Hz at a level of 0 dBm0. Note - If a sinusoidal test signal is used, uncertainties in the absolute level position of the companding law characteristic of a practical encoder require special interpretation of the error lim- its specified in modes A-D, A-A and (if the signal passes via an analogue point) D-D. In these modes, the figures represent the accuracy with which the envelope of the characteristic can be located, rather than the accuracy of any single result Annex A to this Recommendation. Table 3/O.133 [T3.133], p. 4.2.2 Return loss | optional) See Table 4/O.133. H.T. [T4.133] TABLE 4/O.133 _________________________________________________________________ Error limits (dB) Parameter Indicated result A-D D-A A-A D-D _________________________________________________________________ 0 to 30 dB _ | _ | _ | - Return loss | ua) 30 to 40 dB _ | _ | _ | - _________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | a) Measured at a level _" -10 dBm0. Table 4/O.133 [T4.133], p. 4.2.3 Longitudinal conversion loss (LCL) | optional) See Table 5/O.133. H.T. [T5.133] TABLE 5/O.133 _____________________________________________________________ Error limits (dB) Parameter Indicated result A-D D-A A-A D-D _____________________________________________________________ 5 to 40 dB _ | .5 - _ | .5 - LCL | ua) 40 to 56 dB _ | .5 - _ | .5 - _____________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | a) Measured at a level _" -10 dBm0. Table 5/O.133 [T5.133], p. 4.2.4 Longitudinal conversion transfer loss (LCTL) | optional) See Table 6/O.133. H.T. [T6.133] TABLE 6/O.133 ______________________________________________________________ Error limits (dB) Parameter Indicated result A-D D-A A-A D-D ______________________________________________________________ 5 to 40 dB _ | .5 - _ | .5 - LCTL | ua) 40 to 56 dB _ | .5 - _ | .5 - ______________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | a) Measured at a level _" -10 dBm0. Table 6/O.133 [T6.133], p. 4.2.5 Attenuation/frequency distortion See Table 7/O.133. H.T. [T7.133] TABLE 7/O.133 ____________________________________________________________________________________________________________________________________________________________________________________________________________ Error limits (dB) Parameter Frequency range A-D D-A A-A D-D ____________________________________________________________________________________________________________________________________________________________________________________________________________ { Attenuation/frequency distortion | ua) } { 200 to 300 Hz 300 to 3000 Hz 3000 to 3600 Hz } { _ | .08 _ | .05 _ | .08 } { _ | .08 _ | .05 _ | .08 } { _ | .08 _ | .05 _ | .08 } { _ | .08 _ | .05 _ | .08 } a) Measured at a level of 0 or -10 dBm0. Error referred to measurement at approximately 820 Hz/1020 Hz. The specified measurement error is applicable if the measured attenuation/frequency distortion does not exceed 6 dB. Table 7/O.133 [T7.133], p. 4.2.6 Weighted noise See Table 8/O.133. H.T. [T8.133] TABLE 8/O.133 center box; cw(48p) | cw(48p) | cw(24p) sw(24p) sw(24p) sw(24p) , ^ | ^ | c | c | c | c. Parameter Indicated result Error limits (dB) A-D D-A A-A D-D ____________________________________________________________________________________________________________________________________________________________________________________________________________ Weighted noise | ua) { -80 to -75 dBm0p -75 to -70 dBm0p -70 to -20 dBm0p } { _ | .5 _ | .5 _ | | } { _ | .5 _ | .5 _ | | } { _ | .5 _ | .5 _ | | } { _ | .5 _ | .5 _ | | } ____________________________________________________________________________________________________________________________________________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | a) Measurement error includes tolerances of the weighting filter given in Recommendation O.41. Table 8/O.133 [T8.133], p. 4.2.7 Total distortion See Table 9/O.133. H.T. [T9.133] TABLE 9/O.133 _________________________________________________________________________________________________________ Error limits (dB) | ua) Parameter Indicated result | ua) A-D D-A A-A D-D _________________________________________________________________________________________________________ { Total distortion (noise test signal) } 0 to 40 dB _ | .5 _ | .5 _ | .5 _ | .5 { Total distortion (sinusoidal test signal) } 0 to 40 dB _ | .8 _ | .8 _ | .8 { _ | .8 a) With an absolut[text mangled] -72 dBm0. _________________________________________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Note - If a sinusoidal test signal is used, uncertainties in the absolute level position of the companding law characteristic of a practical encoder require special interpretation of the error lim- its specified in modes A-D, A-A and (if the signal passes via an analogue point) D-D. In these modes, the figures represent the accuracy with which the envelope of the characteristic can be located, rather than the accuracy of any single result Annex A to this Recommendation. Table 9/O.133 [T9.133], p. BLANC 4.2.8 Variation of gain with input level See Table 10/O.133. H.T. [T10.133] TABLE 10/O.133 ________________________________________________________________________________________________ Error limits (dB) | ua) Parameter Level range A-D D-A A-A D-D ________________________________________________________________________________________________ { Gain variation (noise test signal) } { -10 to -40 dBm0 -40 to -50 dBm0 -50 to -55 dBm0 } { _ | .10 _ | .15 _ | .15 } { _ | .10 | ub) _ | .15 | ub) _ | .15 | ub) } { _ | .15 | ub) _ | .20 | ub) _ | .20 | ub) } { _ | .10 _ | .10 _ | .10 } ________________________________________________________________________________________________ { Gain variation (sinusoidal test signal at approx. 420, 820 or 1020 Hz) } { +3 to -40 dBm0 -40 to -50 dBm0 -50 to -55 dBm0 } { _ | .10 | ub) _ | .20 | ub) _ | .25 | ub) } { _ | .10 _ | .15 _ | .20 } { _ | .15 _ | .20 _ | .25 } { _ | .10 _ | .15 _ | .20 } ________________________________________________________________________________________________ | | | | | | | | | | | | | | a) Error referred to measurement of -10 dBm0. b) Provisional value, to be studied further. Note - If a sinusoidal test signal is used, uncertainties in the absolute level position of the companding law characteristic of a practical encoder require special interpretation of the error lim- its specified in modes A-D, A-A and (if the signal passes via an analogue point) D-D. In these modes, the figures represent the accuracy with which the envelope of the characteristic can be located, rather than the accuracy of any single result Annex A to this Recommendation. Table 10/O.133 [T10.133], p. 4.2.9 Crosstalk measurement See Table 11/O.133. H.T. [T11.133] TABLE 11/O.133 _____________________________________________________ Error limits (dB) Parameter Remarks A-D D-A A-A D-D _____________________________________________________ { _ | _ | _ | | _ | { Crosstalk - - _ | .5 - _____________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | a) Measurement to be performed while injecting an auxiliary signal in the disturbed channel. Appropriate auxiliary signals are defined in S 3.2.4. Error includes effect of finite rejection of the auxi- liary signal by the measurement filter and of quantizing distortion in the measurement bandwidth. b) Measurement error includes tolerances of the weighting filter given in Recommendation O.41. Table 11/O.133 [T11.133], p. 5 Operating environment The electrical performance requirements shall be met when operating at the climatic conditions as specified in Recommendation O.3, S 2.1. ANNEX A (to Recommendation O.133) Intrinsic errors in the PCM encoding process which may affect the interpretation of measured results A.1 Introduction Pulse Code Modulation (PCM) has some inherent limitations which affect measurements on PCM encoders. This pertains especially to the measurement of the variation of gain with input level and of the quantizing distortion ratio. Due to the limited number of quan- tizing steps available for encoding an analogue signal, the output signal of a PCM decoder is not a replica of the input signal to the encoder. Depending on the actual amplitude of the signal samples to be encoded, as compared with the quantizing thresholds, the output values at the decoder are sometimes greater and sometimes smaller than would occur in a linear system. The differences are called quantizing errors, and exist even for an ideal PCM encoder/decoder pair conforming to a practical encoding law. A test signal will experience the average effect of the quan- tizing errors in all its samples, which depends on the amplitude distribution of the signal. For Gaussian noise, the errors tend to average out, and no measurement problems arise. However, this is not the case for sinusoidal signals, and measurement results for gain linearity and quantizing distortion ratio must be interpreted with care. A.2 Measurement of gain and variation of gain with input level As mentioned in the introduction, the signal at the output of a PCM decoder may differ from what would occur at the output of a linear system. This means that a PCM channel may appear to have unexpected gain when measured with a sinusoidal signal. This "quan- tizing gain" is sometimes positive and sometimes negative and varies with input level. In the case of linear encoding, the more quantizing steps available for encoding the analogue input signal, the smaller the quantizing errors and hence the gain variations. With a truly logarithmic encoding characteristic the quantizing error would be independent of the input level. The encoding laws used in practice (A- and u-law) approximate the logarithmic characteristic by a segmented curve. For the A-law, this results in a gain variation which follows the same rules for the segments No. 7 to No. 2 and which increases with decreasing input level for segment No. 1. Because the values at the segment end points of the u-law characteristic are not multiples of 2 (as with the A-law), the gain variations for the corresponding segment portions are similar but not identical. Figures A-1/O.133 to A-4/O.133 show the (calculated) variation of gain with input level when measuring a PCM channel with an asyn- chronous sinusoidal signal. Because the gain variation in the upper segments is always between +0.043 dB and -0.048 dB, only the level range below -30 dBm0 is shown. The gain has a sharp minimum each time the peak of the sinusoid passes through a decision value. As the input amplitude is increased, the gain rises quickly to a max- imum before falling again. In the vicinity of the minima, the gain can vary substantially when the input level is varied only by small amounts. With the A-law, for example, the gain changes by approxi- mately 0.8 dB (selective measurements) when the input level is varied between -57.00 dB and -57.066 dB. In this case the ratio of level-to-gain variation is 1:11.8. For greater input levels and for the u-law, the variation of gain with input level is smaller but still not negligible. For signal levels above -60 dBm0, the maximum excursions are within a range of approximately -1.3 to +0.65 dB (-1.0 to +0.9 dB) for the A-law, and approximately 0.5 to 0.3 dB (-0.45 to 0.35 dB) for the u-law depending on the measurement mode selective or (wide- band). When measuring the gain variation of a PCM channel with a sinusoidal stimulus, the theoretical considerations described above must be taken into account. Because the relative level at the encoder input need only be set within a limit of _ | .3 dB (Recommendation G.713 [10]), and because the analogue signal gen- erator used for the measurement has some uncertainty in the send level setting, it is not possible to exactly predict the actual position on the encoding characteristic or even to avoid the minima. For this reason, any single measurement result must be treated as relative to the envelope of the gain variation charac- teristic. Additionally, it has to be considered that Figures A-1/O.133 to A-4/O.133 represent theoretical values with ideal encoders having no quantizing thres- hold errors. In practice, deviations from the ideal characteristics due to encoder threshold offset must be expected. This limitation also applies to measurements of gain, although at high levels the error is small - of the order of _ | .04 dB. To simplify the interpretation of measurement results, Tables A-1/O.133 to A-4/O.133 list the extreme values of the gain variation with input level for the A- and u-law for selective and wideband measurements. The tables have 64 lines (multiple of 16), so one line contains the values of corresponding segment portions. For the A-law the corresponding gain values in the first three columns are identical. A.3 Quantizing distortion measurements The quantizing error results in quantizing distortion which varies as function of input level. Figures A-5/O.133 and A-6/O.133 illustrate the (calculated) quantizing distortion characteristics for the A- and u-law when measuring a PCM-channel with a sinusoidal stimulus. As with gain measurements, the quantizing distortion ratio can vary substantially as a result of small variations of the input signal. The variation ratio reaches its maximum at the seg- ment end points. For the same reason as described above, one can again only refer to the envelope of the variation of the quantizing distortion ratio when interpreting individual measurement results. The warning with respect to quantizing threshold errors in a non-ideal encoder applies to quantizing distortion ratio measurements as well. Tables A-5/O.133 and A-6/O.133 contain the extreme values of the quantizing distortion ratio of an ideal encoder when measured with a sinusoidal signal. In the tables, "level" is the input level; S /Q is the ratio of the corresponding level (at the output) of the stimulus, measured selectively, to the quantizing noise, measured flat and with a fixed correction to normalize the noise bandwidth to 3.1 kHz. Note - Tables A-5/O.133 and A-6/O.133 and their accompanying graphs are mainly indicative, since: 1) the calculations (flat S /Q ) do not compare with the weighted ratio ( S +Q )/Q result of the method of Recommendation O.132. They are more similar to the use of a tone stimulus with the filters of Recommendation O.131; 2) the correction to the 3.1 kHz bandwidth assumes the quantizing noise spectrum is flat, whereas it is non-flat and level-dependent (so that no fixed correction will compensate for the lost bandwidth of the stimulus rejection filter). A.4 General notes to tables and graphs The input levels are stated based on values of Tm\da\dxof exactly 3.14 dBm0 for the A-law and 3.17 dBm0 for the u-law. (On this basis, the selective levels of 1 kHz sequences of Recommendation G.711 [1] are -0.0016 dBm0 for a the A-law and -0.0024 dBm0 for the u-law.) The envelope of a characteristic is a pair of smooth curves tangential to the characteristic at or near all its extreme values. H.T. [T12.133] TABLE A-1/O.133 Variation of gain with input level, A-law. Gain calculation based on a selective measurement of the stimulus _______________________________________________________________________________________________________________________________________________ Input level (dBm0) Gain (dB) Input level (dBm0) Gain (dB) Input level (dBm0) Gain (dB) Input level (dBm0) Gain (dB) _______________________________________________________________________________________________________________________________________________ 2.948 0.009 -9.093 0.009 -21.135 0.009 -33.176 0.008 2.864 0.018 -9.177 -0.018 -21.218 -0.018 -33.259 -0.019 2.666 0.009 -9.375 0.009 -21.417 0.009 -33.458 0.009 2.579 -0.019 -9.462 -0.019 -21.503 -0.019 -33.544 -0.020 2.374 0.010 -9.667 0.010 -21.708 0.010 -33.749 0.009 -2.285 -0.020 -9.756 -0.020 -21.797 -0.020 -33.839 -0.021 2.073 0.010 -9.969 0.010 -22.010 0.010 -34.051 0.010 1.980 -0.021 -10.061 -0.021 -22.102 -0.021 -34.143 -0.022 1.760 0.011 -10.281 0.011 -22.322 0.011 -34.363 0.010 1.664 -0.022 -10.377 -0.022 -22.418 -0.022 -34.459 -0.023 1.436 0.012 -10.605 0.012 -22.647 0.012 -34.688 0.011 1.336 -0.024 -10.705 -0.024 -22.746 -0.024 -34.787 -0.025 1.099 0.012 -10.942 0.012 -22.983 0.012 -35.024 0.011 0.996 -0.025 -11.045 -0.025 -23.087 -0.025 -35.128 -0.026 0.749 0.013 -11.293 0.013 -23.334 0.013 -35.375 0.012 0.641 -0.027 -11.400 -0.027 -23.441 -0.027 -35.482 -0.028 0.383 0.014 -11.658 0.014 -23.699 0.014 -35.740 0.013 0.272 -0.028 -11.770 -0.028 -23.811 -0.028 -35.852 -0.030 0.002 0.015 -12.039 0.015 -24.080 0.015 -36.121 0.014 -0.115 -0.030 -12.156 -0.030 -24.197 -0.030 -36.238 -0.032 -0.396 0.017 -12.438 0.017 -24.479 0.017 -36.520 0.015 -0.519 -0.032 -12.560 -0.032 -24.601 -0.032 -36.642 -0.034 -0.814 0.018 -12.856 0.018 -24.897 0.018 -36.937 0.016 -0.942 -0.034 -12.984 -0.034 -25.025 -0.034 -37.066 -0.036 -1.254 0.020 -13.295 0.020 -25.336 0.020 -37.376 0.017 -1.388 -0.036 -13.429 -0.036 -25.470 -0.036 -37.512 -0.039 -1.716 0.023 -13.758 0.023 -25.799 0.023 -37.838 0.019 -1.858 -0.038 -13.899 -0.038 -25.940 -0.038 -37.981 -0.043 -2.206 0.026 -14.248 0.026 -26.289 0.026 -38.327 0.020 -2.354 -0.040 -14.395 -0.040 -26.436 -0.040 -38.478 -0.047 -2.741 0.035 -14.782 0.035 -26.824 0.035 -38.844 0.022 -2.881 -0.018 -14.922 -0.018 -26.963 -0.018 -39.004 -0.051 -3.073 0.009 -15.114 0.009 -27.155 0.009 -39.394 0.024 -3.156 -0.018 -15.198 -0.018 -27.239 -0.018 -39.565 -0.056 -3.355 0.009 -15.396 0.009 -27.437 0.009 -39.982 0.027 -3.441 -0.019 -15.482 -0.019 -27.524 -0.019 -40.164 -0.062 -3.646 0.010 -15.688 0.010 -27.729 0.010 -40.612 0.030 -3.736 -0.020 -15.777 -0.020 -27.818 -0.020 -40.808 -0.070 -3.948 0.010 -15.989 0.010 -28.030 0.010 -41.291 0.034 -4.040 -0.021 -16.082 -0.021 -28.123 -0.021 -41.503 -0.079 -4.261 0.011 -16.302 0.011 -28.343 0.011 -42.029 0.038 -4.356 -0.022 -16.398 -0.022 -28.439 -0.022 -42.259 -0.090 -4.585 0.012 -16.626 0.012 -28.667 0.012 -42.834 0.044 -4.684 -0.024 -16.725 -0.024 -28.767 -0.024 -43.087 -0.104 -4.922 0.012 -16.963 0.012 -29.004 0.012 -43.723 0.051 -5.025 -0.025 -17.066 -0.025 -29.107 -0.025 -44.002 -0.122 -5.272 0.013 -17.313 0.013 -29.354 0.013 -44.713 0.061 -5.379 -0.027 -17.421 -0.027 -29.462 -0.027 -45.025 -0.146 -5.637 0.014 -17.678 0.014 -27.719 0.014 -45.831 0.074 -5.749 -0.028 -17.790 -0.028 -29.831 -0.028 -46.185 -0.178 -6.018 0.015 -18.059 0.015 -30.101 0.015 -47.114 0.092 -6.135 -0.030 -18.176 -0.030 -30.218 -0.030 -47.524 -0.226 -6.417 0.017 -18.458 0.017 -30.499 0.017 -48.623 0.119 -6.539 -0.032 -18.580 -0.032 -30.622 -0.032 -49.107 -0.299 -6.835 0.018 -18.876 0.018 -30.917 0.018 -50.451 0.162 -6.963 -0.034 -19.004 -0.034 -31.045 -0.034 -51.045 -0.423 -7.274 0.020 -19.315 0.020 -31.356 0.020 -52.775 0.240 -7.409 -0.036 -19.450 -0.036 -31.491 -0.036 -53.544 -0.668 -7.737 0.023 -19.778 0.023 -31.819 0.022 -55.976 0.408 -7.878 -0.038 -19.919 -0.038 -31.961 -0.039 -57.066 -1.312 -8.227 0.026 -20.268 0.026 -32.309 0.026 -8.375 -0.040 -20.416 -0.040 -32.457 -0.040 -8.762 0.035 -20.803 0.035 -32.844 0.035 -8.901 -0.018 -20.942 -0.018 -32.984 -0.018 _______________________________________________________________________________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Table A-1/O.133 [T12.133], p. H.T. [T13.133] TABLE A-2/O.133 Variation of gain with input level, A-law. Gain calculation based on a wideband measurement of the stimulus _______________________________________________________________________________________________________________________________________________ Input level (dBm0) Gain (dB) Input level (dBm0) Gain (dB) Input level (dBm0) Gain (dB) Input level (dBm0) Gain (dB) _______________________________________________________________________________________________________________________________________________ 2.947 0.009 -9.094 0.009 -21.135 0.009 -33.176 0.009 2.864 -0.018 -9.177 -0.018 -21.218 -0.018 -33.259 -0.018 2.665 0.010 -9.376 0.010 -21.417 0.010 -33.458 0.010 2.579 -0.019 -9.462 -0.019 -21.503 -0.019 -33.544 -0.019 2.374 0.010 -9.668 0.010 -21.709 0.010 -33.750 0.010 2.285 -0.020 -9.756 -0.020 -21.797 -0.020 -33.839 -0.020 2.072 0.011 -9.969 0.011 -22.010 0.011 -34.052 0.011 1.980 -0.021 -10.061 -0.021 -22.102 -0.021 -34.143 -0.021 1.759 0.012 -10.282 0.012 -22.323 0.012 -34.364 0.011 1.664 -0.022 -10.377 -0.022 -22.418 -0.022 -34.459 -0.022 1.435 0.012 -10.606 0.012 -22.647 0.012 -34.688 0.012 1.336 -0.023 -10.705 -0.023 -22.746 -0.023 -34.787 -0.023 1.098 0.013 -10.943 0.013 -22.984 0.013 -35.025 0.013 0.996 -0.024 -11.045 -0.024 -23.087 -0.024 -35.128 -0.025 0.748 0.014 -11.293 0.014 -23.334 0.014 -35.376 0.013 0.641 -0.026 -11.400 -0.026 -23.441 -0.026 -35.482 -0.026 0.383 0.015 -11.658 0.015 -23.700 0.015 -35.741 0.014 0.272 -0.027 -11.770 -0.027 -23.811 -0.027 -35.852 -0.028 0.001 0.016 -12.040 0.016 -24.081 0.016 -36.122 0.015 -0.115 -0.029 -12.156 -0.029 -24.197 -0.029 -36.238 -0.030 -0.397 0.018 -12.439 0.018 -24.480 0.018 -36.521 0.016 -0.519 -0.031 -12.560 -0.031 -24.601 -0.031 -36.642 -0.032 -0.815 0.019 -12.857 0.019 -24.898 0.019 -36.938 0.018 -0.942 -0.033 -12.984 -0.033 -25.025 -0.033 -37.066 -0.034 -1.255 0.021 -13.296 0.021 -25.337 0.021 -37.378 0.019 -1.388 -0.035 -13.429 -0.035 -25.470 -0.035 -37.512 -0.037 -1.718 0.024 -13.759 0.024 -25.800 0.024 -37.840 0.021 -1.858 -0.037 -13.899 -0.037 -25.940 -0.037 -37.981 -0.040 -2.208 0.027 -14.249 0.027 -26.290 0.027 -38.328 0.023 -2.354 -0.038 -14.395 -0.038 -26.436 -0.038 -38.478 -0.044 -2.742 0.036 -14.783 0.036 -26.825 0.036 -38.846 0.025 -2.881 -0.017 -14.922 -0.017 -26.963 -0.017 -39.004 -0.048 -3.073 0.009 -15.114 0.009 -27.156 0.009 -39.396 0.028 -3.156 -0.018 -15.198 -0.018 -27.239 -0.018 -39.565 -0.053 -3.355 0.010 -15.397 0.010 -27.438 0.010 -39.984 0.031 -3.441 -0.019 -15.482 -0.019 -27.524 -0.019 -40.164 -0.058 -3.647 0.010 -15.688 0.010 -27.729 0.010 -40.615 0.034 -3.736 -0.020 -15.777 -0.020 -27.818 -0.020 -40.808 -0.065 -3.949 0.011 -15.990 0.011 -28.031 0.011 -41.295 0.039 -4.040 -0.021 -16.082 -0.021 -28.123 -0.021 -41.503 -0.073 -4.261 0.012 -16.302 0.012 -28.344 0.012 -42.033 0.044 -4.356 -0.022 -16.398 -0.022 -28.439 -0.022 -42.259 -0.083 -4.585 0.012 -16.627 0.012 -28.668 0.012 -42.839 0.051 -4.684 -0.023 -16.725 -0.023 -28.767 -0.023 -43.087 -0.095 -4.922 0.013 -16.963 0.013 -29.005 0.013 -43.729 0.060 -5.025 -0.024 -17.066 -0.024 -29.107 -0.024 -44.002 -0.111 -5.273 0.014 -17.314 0.014 -29.355 0.014 -44.720 0.072 -5.379 -0.026 -17.421 -0.026 -29.462 -0.026 -45.025 -0.132 -5.638 0.015 -17.679 0.015 -29.720 0.015 -45.840 0.088 -5.749 -0.027 -17.790 -0.027 -29.831 -0.027 -46.185 -0.161 -6.019 0.016 -18.060 0.016 -30.102 0.016 -47.128 0.111 -6.135 -0.029 -18.176 -0.029 -30.218 -0.029 -47.524 -0.202 -6.418 0.018 -18.459 0.018 -30.500 0.018 -48.642 0.146 -6.539 -0.031 -18.580 -0.031 -30.622 -0.031 -49.107 -0.263 -6.836 0.019 -18.877 0.019 -30.918 0.019 -50.480 0.203 -6.963 -0.033 -19.004 -0.033 -31.045 -0.033 -51.045 -0.365 -7.275 0.021 -19.316 0.021 -31.358 0.021 -52.827 0.310 -7.409 -0.035 -19.450 -0.035 -31.491 -0.035 -53.544 -0.556 -7.738 0.024 -19.779 0.024 -31.821 0.023 -56.086 0.554 -7.878 -0.037 -19.919 -0.037 -31.961 -0.037 -57.066 -1.015 -8.228 0.027 -20.269 0.027 -32.311 0.027 -8.375 -0.038 -20.416 -0.038 -32.457 -0.039 -8.763 0.036 -20.804 0.036 -32.845 0.036 -8.901 -0.017 -20.942 -0.017 -32.984 -0.017 _______________________________________________________________________________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Table A-2/O.133 [T13.133], p. H.T. [T14.133] TABLE A-3/O.133 Variation of gain with input level, u-law. Gain calculation based on a selective measurement of the stimulus _______________________________________________________________________________________________________________________________________________ Input level (dBm0) Gain (dB) Input level (dBm0) Gain (dB) Input level (dBm0) Gain (dB) Input level (dBm0) Gain (dB) _______________________________________________________________________________________________________________________________________________ 2.977 0.009 -9.173 0.009 -21.662 0.010 -35.769 0.014 2.893 -0.018 -9.258 -0.019 -21.751 -0.020 -35.882 -0.030 2.694 0.009 -9.459 0.010 -21.964 0.010 -36.154 0.015 2.607 -0.019 -9.547 -0.020 -22.057 -0.021 -36.272 -0.032 2.401 0.010 -9.756 0.010 -22.277 0.011 -36.557 0.016 2.311 -0.020 -9.847 -0.021 -22.373 -0.023 -36.681 -0.034 2.098 0.010 -10.063 0.011 -22.602 0.012 -36.980 0.017 2.005 -0.021 -10.157 -0.022 -22.702 -0.024 -37.110 -0.036 1.784 0.011 -10.382 0.011 -22.940 0.012 -37.425 0.018 1.668 -0.023 -10.479 -0.023 -23.043 -0.025 -37.562 -0.039 1.458 0.012 -10.712 0.012 -23.291 0.013 -37.893 0.020 1.358 -0.024 -10.814 -0.024 -23.399 -0.027 -38.038 -0.043 1.120 0.013 -11.056 0.013 -23.657 0.014 -38.388 0.022 1.016 -0.025 -11.161 -0.026 -23.769 -0.029 -38.541 -0.046 0.767 0.013 -11.414 0.014 -24.039 0.015 -38.914 0.024 0.660 -0.027 -11.524 -0.027 -24.157 -0.030 -37.076 -0.051 0.400 0.014 -11.787 0.015 -23.439 0.016 -39.473 0.027 0.288 -0.028 -11.902 -0.029 -25.562 -0.032 -39.646 -0.056 0.017 0.016 -12.177 0.016 -24.858 0.018 -40.071 0.030 -0.101 -0.030 -12.297 -0.031 -24.987 -0.035 -40.255 -0.062 -0.384 0.017 -12.585 0.017 -25.299 0.019 -40.713 0.034 -0.507 -0.032 -12.711 -0.033 -25.434 -0.037 -40.911 -0.069 -0.805 0.018 -13.014 0.019 -25.763 0.021 -41.406 0.039 -0.934 -0.034 -13.145 -0.035 -25.905 -0.040 -41.621 -0.077 -1.247 0.020 -13.465 0.021 -26.253 0.024 -42.160 0.045 -1.382 -0.036 -13.603 -0.038 -26.403 -0.043 -42.393 -0.087 -1.713 0.023 -13.941 0.024 -26.773 0.027 -42.986 0.054 -1.855 -0.039 -14.086 -0.040 -26.932 -0.046 -43.241 -0.098 -2.206 0.026 -14.446 0.027 -27.327 0.032 -43.902 0.067 -2.355 -0.040 -14.598 -0.041 -27.495 -0.048 -44.181 -0.110 -2.745 0.036 -14.997 0.037 -27.938 0.043 -44.959 0.099 -2.886 -0.018 -15.141 -0.018 -28.097 -0.022 -45.236 -0.054 -3.080 0.009 -15.340 0.009 -28.318 0.011 -45.639 0.026 -3.164 -0.019 -15.426 -0.019 -28.414 -0.023 -45.815 -0.059 -3.364 0.009 -15.632 0.010 -28.643 0.011 -46.247 0.028 -3.451 -0.020 -15.721 -0.020 -28.743 -0.024 -46.435 -0.066 -3.658 0.010 -15.934 0.010 -28.982 0.012 -46.901 0.032 -3.748 -0.021 -16.026 -0.021 -29.086 -0.026 -47.104 -0.074 -3.963 0.010 -16.247 0.011 -29.334 0.013 -47.608 0.036 -4.056 -0.022 -16.343 -0.023 -29.442 -0.027 -47.828 -0.084 -4.278 0.011 -16.571 0.012 -29.701 0.014 -43.378 0.041 -4.375 -0.023 -16.671 -0.024 -29.814 -0.029 -48.618 -0.096 -4.605 0.012 -16.908 0.012 -30.084 0.015 -49.223 0.047 -4.706 -0.024 -17.012 -0.025 -30.202 -0.031 -49.488 -0.112 -4.946 0.013 -17.259 0.013 -30.485 0.016 -50.159 0.056 -5.050 -0.025 -17.367 -0.027 -30.608 -0.033 -50.454 -0.133 -5.300 0.014 -17.625 0.014 -30.906 0.017 -51.209 0.067 -5.408 -0.027 -17.737 -0.028 -31.035 -0.035 -51.541 -0.161 -5.669 0.015 -18.007 0.015 -31.347 0.019 -52.404 0.082 -5.782 -0.029 -18.124 -0.030 -31.483 -0.038 -52.784 -0.200 -6.054 0.016 -18.406 0.017 -31.813 0.021 -53.791 0.104 -6.172 -0.030 -18.528 -0.032 -31.956 -0.041 -54.235 -0.258 -6.458 0.017 -18.824 0.018 -32.305 0.023 -55.444 0.138 -6.581 -0.032 -18.953 -0.034 -32.456 -0.044 -55.978 -0.352 -6.881 0.019 -19.264 0.020 -32.826 0.025 -57.490 0.195 -7.011 -0.035 -19.399 -0.037 -32.987 -0.048 -58.161 -0.522 -7.326 0.021 -19.727 0.022 -33.381 0.029 -7.462 -0.037 -19.869 -0.039 -33.552 -0.053 -7.795 0.023 -20.217 0.025 -33.975 0.053 -7.938 -0.039 -20.367 -0.042 -34.156 -0.057 -8.292 0.027 -20.737 0.029 -34.613 0.039 -8.442 -0.040 -20.894 -0.044 -34.806 -0.060 -8.836 0.036 -21.307 0.039 -35.323 0.054 -8.977 -0.018 -21.456 -0.019 -35.508 -0.028 _______________________________________________________________________________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Table A-3/O.133 [T14.133], p. H.T. [T15.133] TABLE A-4/O.133 Variation of gain with input level, u-law. Gain calculation based on a wideband measurement of the stimulus _______________________________________________________________________________________________________________________________________________ Input level (dBm0) Gain (dB) Input level (dBm0) Gain (dB) Input level (dBm0) Gain (dB) Input level (dBm0) Gain (dB) _______________________________________________________________________________________________________________________________________________ 2.977 0.009 -9.173 0.010 -21.662 0.010 -35.769 0.015 2.893 -0.018 -9.258 -0.018 -21.751 -0.020 -35.882 -0.028 2.693 0.010 -9.460 0.010 -21.965 0.011 -36.155 0.016 2.607 -0.019 -9.547 -0.019 -22.057 -0.021 -36.272 -0.030 2.400 0.010 -9.757 0.011 -22.278 0.012 -36.558 0.017 2.311 -0.020 -9.847 -0.020 -22.373 -0.022 -36.681 -0.032 2.097 0.011 -10.064 0.011 -22.603 0.012 -36.981 0.018 2.005 -0.021 -10.157 -0.021 -22.702 -0.023 -37.110 -0.035 1.783 0.012 -10.382 0.012 -22.940 0.013 -37.426 0.020 1.668 -0.022 -10.479 -0.022 -23.043 -0.024 -37.562 -0.037 1.458 0.012 -10.713 0.013 -23.292 0.014 -37.895 0.022 1.358 -0.023 -10.814 -0.024 -23.399 -0.026 -38.038 -0.041 1.119 0.013 -11.057 0.014 -23.658 0.015 -38.390 0.024 1.016 -0.024 -11.161 -0.025 -23.769 -0.028 -38.541 -0.044 0.767 0.014 -11.415 0.015 -23.040 0.016 -38.916 0.026 0.660 -0.026 -11.524 -0.026 -24.157 -0.029 -37.096 -0.048 0.400 0.015 -11.788 0.016 -24.440 0.017 -39.475 0.029 0.288 -0.027 -11.902 -0.028 -24.562 -0.031 -39.646 -0.053 0.016 0.016 -12.178 0.017 -24.859 0.019 -40.073 0.033 -0.101 -0.029 -12.297 -0.030 -24.987 -0.034 -40.255 -0.058 -0.385 0.018 -12.586 0.018 -25.300 0.021 -40.715 0.037 -0.507 -0.031 -12.711 -0.032 -25.434 -0.036 -40.911 -0.065 -0.806 0.019 -13.015 0.020 -25.764 0.023 -41.409 0.042 -0.934 -0.033 -13.145 -0.034 -25.905 -0.039 -41.621 -0.073 -1.248 0.021 -13.466 0.022 -26.254 0.025 -42.163 0.049 -1.382 -0.035 -13.603 -0.036 -26.403 -0.042 -42.393 -0.082 -1.714 0.024 -13.942 0.025 -26.775 0.028 -42.990 0.058 -1.855 -0.038 -14.086 -0.039 -26.932 -0.045 -43.241 -0.093 -2.208 0.027 -14.447 0.028 -27.329 0.033 -43.907 0.072 -2.355 -0.039 -14.598 -0.040 -27.495 -0.047 -44.181 -0.104 -2.746 0.036 -14.998 0.038 -27.939 0.044 -44.963 0.104 -2.886 -0.017 -15.141 -0.018 -28.097 -0.021 -45.236 -0.050 -3.080 0.009 -15.340 0.010 -28.318 0.012 -45.641 0.029 -3.164 -0.018 -15.426 -0.019 -28.414 -0.022 -45.815 -0.055 -3.365 0.010 -15.632 0.010 -28.644 0.012 -46.249 0.032 -3.451 -0.019 -15.721 -0.020 -28.743 -0.023 -46.435 -0.061 -3.659 0.011 -15.934 0.011 -28.983 0.013 -46.904 0.036 -3.748 -0.020 -16.026 -0.021 -29.086 -0.025 -47.104 -0.069 -3.963 0.011 -16.247 0.012 -29.335 0.014 -47.611 0.041 -4.056 -0.021 -16.343 -0.022 -29.442 -0.026 -47.828 -0.078 -4.279 0.012 -16.572 0.012 -29.702 0.015 -48.382 0.047 -4.375 -0.022 -16.671 -0.023 -29.814 -0.028 -48.618 -0.089 -4.606 0.013 -16.909 0.013 -30.085 0.016 -49.228 0.055 -4.706 -0.023 -17.012 -0.024 -30.202 -0.030 -49.488 -0.103 -4.946 0.013 -17.260 0.014 -30.486 0.017 -50.166 0.065 -5.050 -0.025 -17.367 -0.026 -30.608 -0.032 -50.454 -0.121 -5.300 0.014 -17.626 0.015 -30.907 0.019 -51.218 0.079 -5.408 -0.026 -17.737 -0.027 -31.035 -0.034 -51.541 -0.145 -5.670 0.015 -18.007 0.016 -31.349 0.020 -52.416 0.098 -5.782 -0.028 -18.124 -0.029 -31.483 -0.037 -52.784 -0.179 -6.055 0.017 -18.407 0.018 -31.814 0.022 -53.807 0.126 -6.172 -0.029 -18.528 -0.031 -31.956 -0.039 -54.235 -0.229 -6.459 0.018 -18.825 0.019 -32.306 0.024 -55.467 0.170 -6.581 -0.031 -18.953 -0.033 -32.456 -0.043 -55.978 -0.307 -6.882 0.020 -19.265 0.021 -32.828 0.027 -57.529 0.247 -7.011 -0.033 -19.399 -0.036 -32.987 -0.046 -58.161 -0.444 -7.327 0.022 -19.729 0.023 -33.383 0.030 -7.462 -0.036 -19.869 -0.038 -33.552 -0.050 -7.796 0.024 -20.219 0.026 -33.976 0.035 -7.938 -0.038 -20.367 -0.041 -34.156 -0.055 -8.294 0.028 -20.739 0.030 -34.615 0.041 -8.442 -0.039 -20.894 -0.042 -34.806 -0.058 -8.837 0.037 -21.309 0.040 -35.325 0.056 -8.977 -0.017 -21.456 -0.019 -35.508 -0.027 _______________________________________________________________________________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Table A-4/O.133 [T15.133], p. H.T. [T16.133] TABLE A-5/O.133 Quantizing distortion ratio, A-law _____________________________________________________________________________________________________________________________________________ Input level (dBm0) S/Q (dB) Input level (dBm0) S/Q (dB) Input level (dBm0) S/Q (dB) Input level (dBm0) S/Q (dB) _____________________________________________________________________________________________________________________________________________ 3.050 40.768 -8.991 40.767 -21.032 40.739 -33.070 39.178 2.879 39.769 -9.162 39.769 -21.203 39.745 -33.246 38.390 2.771 40.565 -9.270 40.565 -21.311 40.535 -33.348 38.904 2.595 39.537 -9.446 39.537 -21.488 39.512 -33.531 38.100 2.483 40.361 -9.558 40.361 -21.599 40.329 -33.636 38.621 2.301 39.301 -9.740 39.301 -21.781 39.275 -33.825 37.800 2.185 40.156 -9.856 40.155 -21.897 40.122 -33.934 38.328 1.997 39.061 -10.044 39.061 -22.086 39.033 -34.130 37.490 1.877 39.950 -10.165 39.949 -22.206 39.914 -34.242 38.025 1.682 38.817 -10.360 38.817 -22.401 38.788 -34.445 37.168 1.557 39.744 -10.485 39.744 -22.526 39.706 -34.561 37.711 1.354 38.570 -10.687 38.569 -22.728 38.539 -34.773 36.834 1.224 39.541 -10.817 39.541 -22.858 39.501 -34.893 37.386 1.014 38.320 -11.027 38.320 -23.068 38.287 -35.113 36.487 0.879 39.343 -11.162 39.342 -23.204 39.299 -35.238 37.047 0.661 38.070 -11.380 38.069 -23.422 38.034 -35.467 36.126 0.519 39.153 -11.522 39.152 -23.563 39.105 -35.597 36.694 0.292 37.820 -11.749 37.819 -23.790 37.782 -35.836 35.749 0.143 38.976 -11.898 38.975 -23.939 38.924 -35.971 36.327 -0.093 37.575 -12.134 37.574 -24.175 37.534 -36.222 35.355 -0.250 38.819 -12.291 38.819 -24.332 38.762 -36.362 35.943 -0.496 37.339 -12.537 37.339 -24.578 37.295 -36.626 34.942 -0.661 38.697 -12.702 38.696 -24.743 38.633 -36.772 35.541 -0.918 37.122 -12.959 37.122 -25.000 37.073 -37.049 34.509 -1.094 38.631 -13.135 38.630 -25.176 38.558 -37.202 35.119 -1.361 36.941 -13.403 36.940 -25.444 36.887 -37.494 34.054 -1.549 38.665 -13.591 38.664 -25.632 38.579 -37.655 34.676 -1.828 36.831 -13.870 36.831 -25.911 36.767 -37.963 33.574 -2.032 38.907 -14.073 38.906 -26.114 38.800 -38.132 34.208 -2.320 36.893 -14.362 36.891 -26.403 36.817 -38.460 33.066 -2.552 39.774 -14.593 39.771 -26.634 39.618 -38.638 33.714 -2.811 37.910 -14.852 37.908 -26.894 37.798 -38.986 32.526 -2.971 40.768 -15.012 40.764 -27.053 40.542 -39.174 33.189 -3.141 39.769 -15.183 39.766 -27.224 39.578 -39.546 31.952 -3.249 40.565 -15.291 40.562 -27.331 40.328 -39.746 32.631 -3.426 39.537 -15.467 39.534 -27.508 39.337 -40.145 31.337 -3.537 40.361 -15.579 40.357 -27.619 40.111 -40.357 32.033 -3.720 39.301 -15.761 39.298 -27.802 39.091 -40.789 30.676 -3.835 40.156 -15.877 40.151 -27.917 39.891 -41.016 31.391 -4.024 39.061 -16.065 39.058 -28.107 38.841 -41.485 29.960 -4.144 39.950 -16.185 39.945 -28.226 39.669 -41.728 30.697 -4.339 38.817 -16.380 38.814 -28.422 38.585 -42.251 29.183 -4.464 39.744 -16.505 39.740 -28.546 39.446 -42.504 29.941 -4.666 38.570 -16.707 38.566 -28.749 38.324 -43.075 28.326 -4.796 39.541 -16.837 39.536 -28.878 39.223 -43.356 29.113 -5.006 38.320 -17.047 38.316 -29.089 38.059 -44.002 27.353 -5.142 39.343 -17.183 39.338 -29.223 39.000 -44.301 28.195 -5.360 38.070 -17.401 38.065 -29.443 37.792 -45.025 26.277 -5.502 39.153 -17.543 39.147 -29.583 38.782 -45.361 27.168 -5.729 37.820 -17.770 37.815 -29.811 37.522 -46.185 25.051 -5.877 38.976 -17.919 38.969 -29.959 38.571 -46.569 25.999 -6.113 37.575 -18.155 37.570 -30.197 37.253 -47.524 23.623 -6.270 38.819 -18.311 38.812 -30.351 38.374 -47.973 24.645 -6.516 37.339 -18.557 37.334 -30.599 36.990 -49.108 21.914 -6.682 38.697 -18.723 38.689 -30.763 38.200 -49.649 23.034 -6.938 37.122 -18.980 37.116 -31.022 36.738 -51.046 19.779 -7.114 38.631 -19.155 38.622 -31.195 38.065 -51.729 21.045 -7.382 36.941 -19.423 36.934 -31.465 36.513 -53.545 16.935 -7.570 38.665 -19.611 38.655 -31.651 38.004 -54.477 18.438 -7.849 36.831 -19.890 36.824 -31.933 36.343 -57.066 12.603 -8.053 38.907 -20.094 38.894 -32.133 38.093 -58.554 14.638 -8.341 36.892 -20.382 36.883 -32.425 36.309 -8.572 39.774 -20.613 39.754 -32.652 38.628 -8.832 37.910 -20.873 37.896 -32.916 37.064 _____________________________________________________________________________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Note - The stimulus S is measured selectively at the output of the test object. The quantizing products Q are measured with an effec- tive noise bandwidth of 3.1 kHz. Table A-5/O.133 [T16.133], p. H.T. [T17.133] TABLE A-6/O.133 Quantizing distortion ratio, u-law ___________________________________________________________________________________________________________________________________________________ Input level (dBm0) S/Q (dB) Input level (dBm0) S/Q (dB) Input level (dBm0) S/Q (dB) Input level (dBm0) S/Q (dB) ___________________________________________________________________________________________________________________________________________________ 3.080 40.722 -9.069 40.585 -21.552 40.016 -35.627 37.431 2.908 39.723 -9.242 39.583 -21.735 39.006 -35.864 36.366 2.800 40.519 -9.352 40.376 -21.850 39.789 -36.006 37.104 2.623 39.490 -9.532 39.345 -22.040 38.748 -36.254 36.003 2.510 40.313 -9.645 40.166 -22.159 39.558 -36.402 36.764 2.327 39.252 -9.831 39.301 -22.356 38.485 -36.662 35.625 2.211 40.106 -9.948 39.953 -22.480 39.324 -36.817 36.413 2.022 39.010 -10.141 38.856 -22.684 38.215 -37.090 35.232 1.901 39.898 -10.263 39.740 -22.813 39.087 -37.253 36.049 1.705 38.764 -10.462 38.604 -23.025 37.939 -37.541 34.821 1.580 39.691 -10.589 39.527 -23.159 38.849 -37.712 35.671 1.376 38.515 -10.796 38.349 -23.380 37.657 -38.016 34.391 1.246 39.486 -10.928 39.316 -23.520 38.610 -38.197 35.279 1.035 38.263 -11.142 38.090 -23.750 37.370 -38.519 33.941 0.898 39.825 -11.281 39.109 -23.896 38.373 -38.711 34.873 0.679 38.010 -11.504 37.830 -24.136 37.079 -35.052 33.469 0.536 39.092 -11.649 38.908 -24.290 38.141 -39.257 34.454 0.308 37.758 -11.881 37.570 -24.540 36.786 -39.621 32.975 0.159 38.912 -12.033 38.720 -24.702 37.918 -39.840 34.023 -0.079 37.510 -12.275 37.314 -24.964 36.492 -40.229 32.457 -0.236 38.753 -12.435 38.553 -25.135 37.711 -40.465 33.582 -0.484 37.272 -12.687 37.066 -25.409 36.204 -40.883 31.914 -0.650 38.628 -12.857 38.417 -25.591 37.533 -41.139 33.141 -0.909 37.051 -13.120 36.836 -25.879 35.928 -41.590 31.351 -1.086 38.558 -13.300 38.337 -26.073 37.405 -41.871 32.713 -1.355 36.867 -13.576 36.640 -26.375 35.682 -42.360 30.775 -1.545 38.589 -13.769 38.355 -25.584 37.371 -42.671 32.335 -1.826 36.753 -14.056 36.513 -26.900 35.500 -43.203 30.212 -2.031 38.826 -14.266 38.579 -27.128 37.534 -43.557 32.102 -2.321 36.809 -14.563 36.556 -27.458 35.480 -44.134 29.751 -2.554 39.688 -14.801 39.425 -27.719 38.307 -44.559 32.424 -2.816 37.822 -15.070 37.554 -28.018 36.411 -45.106 30.244 -2.976 40.677 -15.234 40.398 -28.199 39.212 -45.411 32.915 -3.149 39.677 -15.411 39.394 -28.398 38.188 -45.796 31.650 -3.258 40.471 -15.522 40.184 -28.520 38.956 -46.002 32.337 -3.436 39.442 -15.705 39.150 -28.726 37.901 -46.417 31.013 -3.548 40.264 -15.821 39.967 -28.854 38.695 -46.636 31.718 -3.732 39.203 -16.010 38.901 -29.068 37.605 -47.086 30.325 -3.849 40.055 -16.129 39.747 -29.201 38.428 -47.320 31.051 -4.039 38.959 -16.326 38.646 -29.424 37.301 -47.811 29.580 -4.160 39.846 -16.450 39.527 -29.562 38.155 -48.063 30.327 -4.357 38.711 -16.653 38.387 -29.795 36.987 -48.611 28.765 -4.483 39.636 -16.782 39.306 -29.939 37.878 -48.875 29.537 -4.668 38.460 -16.993 38.123 -30.182 36.665 -49.488 27.845 -4.819 39.429 -17.128 39.086 -30.334 37.598 -49.771 28.666 -5.031 38.206 -17.348 37.856 -30.588 36.334 -50.454 26.831 -5.168 39.226 -17.489 38.869 -30.747 37.315 -50.770 27.697 -5.388 37.951 -17.717 37.586 -31.013 35.994 -51.541 25.684 -5.532 39.031 -17.865 38.658 -31.181 37.032 -51.900 26.603 -5.761 37.696 -18.103 37.315 -31.460 35.647 -52.784 24.365 -5.912 38.849 -18.258 38.459 -31.638 36.753 -53.198 25.349 -6.151 37.445 -18.506 37.047 -31.932 35.295 -54.235 22.808 -6.309 38.687 -18.670 38.279 -32.120 36.485 -54.726 23.878 -6.558 37.204 -18.929 36.786 -32.430 34.941 -55.978 20.910 -6.726 38.558 -19.102 38.130 -32.631 36.239 -56.582 22.098 -6.986 36.980 -19.374 36.541 -32.959 34.593 -58.161 18.473 -7.164 38.485 -19.558 38.035 -33.175 36.034 -58.949 19.842 -7.435 36.792 -19.842 36.330 -33.521 34.265 -7.626 38.512 -20.040 38.037 -33.756 35.913 -7.909 36.674 -20.336 36.186 -34.122 33.991 -8.116 38.745 -20.552 38.241 -34.381 35.978 -8.408 36.725 -20.859 36.208 -34.766 33.865 -8.643 39.601 -21.104 39.064 -35.065 36.635 -8.907 37.733 -21.382 37.185 -35.418 33.687 ___________________________________________________________________________________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Note - The stimulus S is measured selectively at the output of the test object. The quantizing products Q are measured with an effec- tive noise bandwidth of 3.1 kHz. Table A-6/O.133 [T17.133]], p. Figure A-1/O.133, p. 23 Figure A-2/O.133, p. 24 Figure A-3/O.133, p. 25 Figure A-4/O.133, p. 26 Figure A-5/O.133, p. 27 Figure A-6/O.133, p. 28 References [1] CCITT Recommendation Pulse code modulation (PCM) of voice frequencies , Vol. III, Rec. G.711. [2] CCITT Recommendation Characteristics of primary PCM multiplex equipment operating at 2048 kbit/s , Vol. III, Rec. G.732. [3] CCITT Recommendation Characteristics of primary PCM multiplex equipment operating at 1544 kbit/s , Vol. III, Rec. G.733. [4] CCITT Recommendation Characteristics of 60-channel transmultiplexing equipments , Vol. III, Rec. G.793. [5] CCITT Recommendation Characteristics of 24-channel transmultiplexing equipments , Vol. III, Rec. G.794. [6] CCITT Recommendation Transmission characteristics for transit exchanges , Red Book, Vol. VI, Rec. Q.517, ITU, Geneva, 1984. [7] CCITT Recommendation Physical/electrical characteris- tics of hierarchical digital interfaces , Vol. III, Rec. G.703. [8] CCITT Recommendation 12-channel terminal equipments , Vol. III, Rec. G.232. [9] CCITT Recommendation Performance characteristics of PCM channels between 4-wire interfaces at voice frequencies , Vol. III, Rec. G.712. [10] CCITT Recommendation Performance characteristics of PCM channels between 2-wire interfaces at voice frequencies , Vol. III, Rec. G.713. [11] CCITT Recommendation Functional characteristics of interface associated with network nodes , Vol. III, Rec. G.704. [12] CCITT Recommendation Separate performance characteris- tics for the send and receive sides of PCM channels applicable to 4-wire voice-frequency interfaces , Vol. III, Rec. G.714. [13] CCITT Recommendation Characteristics common to all transmultiplexing equipments , Vol. III, Rec. G.792.