* High-accuracy analog
inputs
The board also has two channels of 16-bit analog output with 8-times oversampling filters and 64-times oversampling delta-sigma modulating DACs. Analog output filters smooth the waveform to remove unwanted higher frequency images.
Applications
The SB-A2200 provides the computational power so that many test and measurement
applications can operate in real time
(see Figure 1). You can use the SB-A2200
for analysis of audio bandwidth signals
(DC to 22 kHz) or in numerically intensive applications. You can use high-speed
data acquisition combined with the simultaneous digital signal analysis
capabilities of the
SB-A2200 in real-time applications such
as spectral analysis, digital filtering, waveform analysis, and statistical
analysis.
The computational power of the SB-A2200 makes it ideal for vector multiply and
add applications. The SB-A2200 has unique versatility and real-time performance
capabilities, which you can use in the following applications:
* Vibration and machine test
* Instrumentation and spectral analysis
* Voice and speech analysis
* Audio and acoustics
* Analog telephony
* Medical research
* Sonar
* Distortion measurements
In addition, the high-resolution audio frequency A/D and D/A is used for digitizing and synthesizing signals with 22 kHz bandwidth or less. The antialiasing filters on the input and the anti-imaging filters on the output ensure that signals are acquired and reproduced with extremely high fidelity. Applications include audio signal processing and analysis, audio workstations, audio and music synthesis, acoustics and speech research, and sonar and audio frequency test and measurement.
Hardware
Analog Inputs - The SB-A2200 has two channels of 16-bit resolution analog
input. The channels are simultaneously sampled
at various software-programmable rates, including divisions of 32.0, 48.0, and
51.2 kS/s (32.0 and 48.0 kS/s are standard rates used in digital audio tape (DAT)
recorders, and 51.2 kS/s is a standard frequency for use with Fourier analysis).
| Board | Sampling Rates |
|---|---|
| SB-A2200 | 4, 6, 6.4, 8, 12, 12.8, 16, 24, 25.6, 32, 48, and 51.2 kS/s |
The analog input has software-programmable AC/DC coupling and can digitize signals within a voltage range of ±2.828 V (2 Vrms). To prevent damage to the board, the input circuitry also has overvoltage protection for inputs up to ±20 V.
Analog Input Antialiasing Filters - The
SB-A2200 has both analog and real-time digital filters implemented in hardware to
prevent aliasing. Input signals are first filtered with analog filters to remove
any signals with frequency components beyond the range of the SB-A2200. Then,
digital antialiasing filters automatically adjust their cutoff frequency to
remove any frequency components above one-half the programmed sampling rate.
Because of this advanced analog input design, you do not have to
add any filters to prevent aliasing.
The analog input stage acquires signals with extremely low noise and low distortion. The board has a 93 dB dynamic range that makes it possible to acquire waveforms without significant noise error. Because the board has a THD of only -95 dB, the digitized signals are a true representation of the analog signal applied to the input of the board. Signals from DC to 22 kHz are acquired with accurate amplitude because the amplitude flatness in this frequency range is within ±0.05 dB.
The low noise and low distortion of the SB-A2200 are achieved by using state-of- the-art 64-times oversampling, delta-sigma modulating ADCs. These ADCs sample at 64 times the specified sampling rate with 1-bit resolution. A noise-shaping technique then shifts quantization noise to higher frequencies. Extremely flat, linear-phase, lowpass digital filters then remove this noise, divide the sample rate by 64, and increase the resolution to 16 bits. Using the delta-sigma modulating ADCs, the SB-A2200 is immune to DNL distortion associated with conventional DAQ boards.
The offset voltage of the analog input is self-calibrated by software to within ±5 LSBs. The gain accuracy is calibrated to within ±0.05 dB by adjusting onboard trimpots.
| Board | Update Rates |
|---|---|
| SB-A2200 | 4, 6, 6.4, 8, 12, 12.8, 16, 24, 25.6, 32, 48, and 51.2 kS/s |
Analog Outputs - The SB-A2200 has two channels of 16-bit resolution analog output. The channels are simultaneously updated at various software programmable rates, including divisions of 32.0, 48.0, and 51.2 kS/s. The analog output circuitry uses 8-times oversampling filters with 64-times oversampling delta-sigma modulators to generate high-quality signals. The board can generate signals within a range of ±2.828 V (2 Vrms).
Analog Output Antialiasing Filters - SB-A2200 has both analog and digital anti-imaging filters. These filters remove unwanted glitches and high-frequency signals that are generated when an analog signal is generated from digital data. The digital filters limit the bandwidth of the output signal to half the original conversion rate, thereby rejecting images caused by the 8-times oversampling process. The analog filters reject unwanted images created by the DAC.
The signals generated by the analog output circuitry are low-distortion, low-noise, frequency-flat analog signals. The dynamic range is 92 dB and IMD is -90 dB. The analog output circuitry has a gain adjustment range of ±0.5 dB and offset accuracy within ±3 mV.
Interrupts - The SB-A2200 and the SPARCstation can communicate with each other by sending interrupts. The SB-A2200 can interrupt the SPARCstation by asserting an interrupt request line on the SBus.
Software
The following software is included with the SB-A2200:
* NI-DAQ for Sun
The following software is available separately:
* LabVIEW
Detailed information on this software can be found in Section 2.
Part Numbers
Hardware and Software
SB-A2200
with 128 Kwords of memory 776795-01
with 512 Kwords of memory 776795-02
Type RCA1 single cable
3 ft 181341-03
6 ft 181341-06
Type RCA2 dual cable
3 ft 181342-03
6 ft 181342-06
