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HamCall (October 1991)
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HamCall (Whitehall Publishing)(1991).bin
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cwxcrv
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cw_fxs.doc
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1990-10-14
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The code speed standard used by the morse code tranceiver program is
based on a word length of 50 elements. An example is "PARIS" consisting of (10
dots x 1 elm. = 10) + (4 dash x 3 elm. = 12) + (9 dot or dash elm space x 1
elm = 9) + (4 ltr space x 3 = 12) + (1 word space x 7 = 7) = 50. One word per
minute is then 60 sec./ 50 elements = 1.2 sec/elm or 1200 mili-seconds/elm.
Therefore Element time in ms = 1200/WPM or WPM = 1200/elm time in ms.
The default fixed speeds are: S5, f5, 7.5, 10, 13, 15, 18, 20, 25, 30,
35, 40, 45, 50, 55, 60, 65 and 70 WPM. Slow fixed speeds use expanded spacing.
As an example the dot, dash and element space of s5 (slow 5) are at a 13 WPM
rate (elm length = 92.3ms) with character and word spacings expanded to
produce an overall 5 WPM rate described as 13e5. Similarly f5 (fast 5) is
16e5, 7.5 is 16e7.5 and 10 is 16e10. Speeds from 13 to 70 WPM use normal
character and word spacings.
Speed Dot Dash Elmsp Chrsp Wrdsp
WPM Ms Ms Ms Ms Ms
x1 x3 x1 Expanded
13e5 92.3 276.9 92.3 1442.9 3366.8
16e5 75 225 75 1527.6 3564.5
16e7.5 75 225 75 896.1 2090.8
16e10 75 225 75 580.3 1354
x1 x3 x1 x3 x7
13 92.3 276.9 92.3 276.9 646.2
15 80 240 80 240 560
18 66.7 200 66.7 200 466.7
20 60 180 60 180 420
25 48 144 48 144 336
30 40 120 40 120 280
35 34.3 102.9 34.3 102.9 240
40 30 90 30 90 210
45 26.7 80 26.7 80 186.7
50 24 72 24 72 168
55 21.8 65.5 21.8 65.5 152.7
60 20 60 20 60 140
65 18.5 55.4 18.5 55.4 129.2
70 17.1 51.4 17.1 51.4 120
The main program CW.EXE contains the fixed tx speed control data
required to produce the 18 default fixed Tx speeds as listed above. Upon CW
program initialization the file CW_FXS.OVL if it found is read from the disk
replacing the default fixed tx speed control data. This procedure allows the
the fixed Tx speeds to be changed or calibrated by editing the file CW_FXS.OVL
with "debug" or any other hex editor. The file is structured as follows:
The first 54 bytes at offset 0 through 53 (35h) are the 18 three byte
ASCII speed values. Each value must be unique and right justified with leading
blanks as required for the three byte length. These ASCII speed values are
used to select and then display the selected fixed tx speed.
The next 180 bytes at offset 54 (36h) through 233 (E9h) are, in the
same sequence as the ASCII speed values, the 18 five word (10 bite) binary
speed control values. Each group of 5 words consist of, in sequence, the dot
length, dash length, element space length, character space length and the
word space length value. Please note that the word space length value is
equal to the required word space length less the character space length.
In fixed speed mode the resolution of all CW element lengths is 100
micro seconds. (0.1 Ms). The approximate CW element speed control value is
therefore equal to: required length in ms / 0.1.
CALIBRATION PROCEDURE
1. Equipment required: A high quality counter capable of time interval
measurment. Set resolution to read .001 or .1 ms as desired. Connect to
selected output port pin 20 (DTR).
2. Load five message buffers with about one line of the following
sequences. 1. Series of E's. 2. Series of T's. 3. Series of 5's. 4. Series
of 0's. 5. Series of E's and spaces.
3. Set leading edge trigger positive (+) and trailing edge trigger
negative (-) to measure dot or dash length. Set leading edge trigger negative
(-) and trailing edge trigger positive (+) to measure Character, Element or
Word spacing.
Signal Trig Trig
+ - - +
E's Dot Character space
T's Dash Character space
5's Dot Element space
0's Dash Element space
E & space Dot Word space
4. Adjust CW_FXS.OVL speed control values as required.
The default fixed tx speed control values were obtained by use of the
above calibration procedure with the CW program running on a Turbo XT machine
using a 8088 processor. Slightly faster (shorter CW element lengths) were
measured on a AT 286 machine.