Date: Tue, 28 Nov 89 18:31:13 -0800
From: Marc T. Kaufman <kaufman@Neon.Stanford.EDU>
Message-Id: <8911290231.AA25951@Neon.Stanford.EDU>
Subject: Re: TAPR 9600 RAdio/Modems???
Enclosed is a new ROM for you to try with the 56KB modem, if you are
interested. (actually, it is a rom description and a program to compile
the ROM itself).
The waveshape used here is a band-limited, continuous-phase, pulse of
length L = 2T. Each 16 bit run has the last half of the previous pulse,
and the first half of the current pulse. The total bandwidth should be
on the order of (99% = 2.2 x b), which is OK since you would expect sidebands
at +/- 1 x b (for a bandwidth of 2 x b) anyway, unless you are using TFM with
a fairly long spread.
Anyway, try it if you have time, and tell me how it compares to Heatherington's
original.
Marc Kaufman (kaufman@Neon.stanford.edu)
***** program to make the rom *****
/* Program to build ROMs for Heatherington 56Kb modem
*
* Written by Marc Kaufman, WB6ECE
* 6 September 1987
*
* usage: mkrom < Romdatafile > binaryromfile
*/
#include <stdio.h>
#define ROMSZ 1024
#define LINESZ 100
#define TRUE 1
#define FALSE 0
char rom[ROMSZ];
char line[LINESZ];
main() {
int addr, j;
int mode, innum, minus;
char *p, c;
for (addr = 0; addr < ROMSZ; addr++)
rom[addr] = 0377;
while (fgets(line, LINESZ, stdin) != NULL) {
switch (line[0]) {
case '.': /* waveshape data */
mode = 0;
sscanf(&line[1], "%d", &addr);
break;
case '=': /* state table data */
mode = 1;
sscanf(&line[1], "%d", &addr);
break;
case '/': /* comments */
case '\n':
break;
default: /* line of data */
p = line;
innum = FALSE;
minus = FALSE;
j = 0;
while (c = *p++) {
if (c == '-') {
minus = TRUE;
} else if (c >= '0' && c <= '9') {
innum = TRUE;
if (mode == 0)
j = 10*j + c - '0';
else
j = 4*j + c - '0';
}
else
if (innum) {
if (mode == 0)
if (minus)
j = 128 - j;
else
j = 128 + j;
rom[addr++] = j;
innum = FALSE;
minus = FALSE;
j = 0;
}
}
break;
}
}
write(fileno(stdout), rom, ROMSZ);
}
***** data for program *****
/ ROM data for Heatherington 56Kb modem
/ Developed by Marc Kaufman, WB6ECE
/ 6 September 1987
/ data portion. Each waveform segment is 1/2 of an L=2 CPM wave, so it is
/ the first half of the wave we want, plus the last half of
/ the previous wave. The suffix 'S' or 'O' indicates whether
/ the current bit is going in the Same direction (in terms of
/ phasor rotation) or is Opposed (phasor reverses direction).
/ The NRZI algorithm says that if the current bit is '1', go
/ the same way (the result will be another FM pulse of the
/ same polarity as the last), and if the bit is a '0', go the
/ other way (the result will be an FM pulse of the opposite
/ polarity to the last).
/ Q data -
.512
/ state 0, clock 0, (0 -> 1)S
-87 -77 -66 -55 -43 -31 -20 -8 4 15 27 39 51 62 73 84
/ state 0, clock 1, (1 -> 0)S
94 102 109 116 120 124 126 127 127 127 124 121 117 111 104 96
/ state 0, clock 2, (0 -> -1)S
86 76 65 54 42 30 19 7 -5 -16 -28 -40 -52 -63 -74 -85
/ state 0, clock 3, (-1 -> 0)S
-95 -103 -110 -117 -121 -125 -127 -128 -128 -128 -125 -122 -118 -112 -105 -97
/ state 1, clock 0, (0 -> -1)S
86 76 65 54 42 30 19 7 -5 -16 -28 -40 -52 -63 -74 -85
/ state 1, clock 1, (-1 -> 0)S
-95 -103 -110 -117 -121 -125 -127 -128 -128 -128 -125 -122 -118 -112 -105 -97
/ state 1, clock 2, (0 -> 1)S
-87 -77 -66 -55 -43 -31 -20 -8 4 15 27 39 51 62 73 84
/ state 1, clock 3, (1 -> 0)S
94 102 109 116 120 124 126 127 127 127 124 121 117 111 104 96
/ state 2, clock 0, (0 -> 1)O
84 71 58 45 34 25 18 15 15 18 25 34 45 58 71 84
/ state 2, clock 1, (1 -> 0)O
96 106 114 119 123 125 126 127 127 126 125 123 119 114 106 96
/ state 2, clock 2, (0 -> 1)O
84 71 58 45 34 25 18 15 15 18 25 34 45 58 71 84
/ state 2, clock 3, (1 -> 0)O
96 106 114 119 123 125 126 127 127 126 125 123 119 114 106 96
/ state 3, clock 0, (0 -> -1)O
-85 -72 -59 -46 -35 -26 -19 -16 -16 -19 -26 -35 -46 -59 -72 -85
/ state 3, clock 1, (-1 -> 0)O
-97 -107 -115 -120 -124 -126 -127 -128 -128 -127 -126 -124 -120 -115 -107 -97
/ state 3, clock 2, (0 -> -1)O
-85 -72 -59 -46 -35 -26 -19 -16 -16 -19 -26 -35 -46 -59 -72 -85
/ state 3, clock 3, (-1 -> 0)O
-97 -107 -115 -120 -124 -126 -127 -128 -128 -127 -126 -124 -120 -115 -107 -97
/ I data - just like Q data, but permuted by 1 clock (quadrature)
.768
/ state 0, clock 0, (1 -> 0)S
94 102 109 116 120 124 126 127 127 127 124 121 117 111 104 96
/ state 0, clock 1, (0 -> -1)S
86 76 65 54 42 30 19 7 -5 -16 -28 -40 -52 -63 -74 -85
/ state 0, clock 2, (-1 -> 0)S
-95 -103 -110 -117 -121 -125 -127 -128 -128 -128 -125 -122 -118 -112 -105 -97
/ state 0, clock 3, (0 -> 1)S
-87 -77 -66 -55 -43 -31 -20 -8 4 15 27 39 51 62 73 84
/ state 1, clock 0, (-1 -> 0)S
-95 -103 -110 -117 -121 -125 -127 -128 -128 -128 -125 -122 -118 -112 -105 -97
/ state 1, clock 1, (0 -> 1)S
-87 -77 -66 -55 -43 -31 -20 -8 4 15 27 39 51 62 73 84
/ state 1, clock 2, (1 -> 0)S
94 102 109 116 120 124 126 127 127 127 124 121 117 111 104 96
/ state 1, clock 3, (0 -> -1)S
86 76 65 54 42 30 19 7 -5 -16 -28 -40 -52 -63 -74 -85
/ state 2, clock 0, (1 -> 0)O
96 106 114 119 123 125 126 127 127 126 125 123 119 114 106 96
/ state 2, clock 1, (0 -> 1)O
84 71 58 45 34 25 18 15 15 18 25 34 45 58 71 84
/ state 2, clock 2, (1 -> 0)O
96 106 114 119 123 125 126 127 127 126 125 123 119 114 106 96
/ state 2, clock 3, (0 -> 1)O
84 71 58 45 34 25 18 15 15 18 25 34 45 58 71 84
/ state 3, clock 0, (-1 -> 0)O
-97 -107 -115 -120 -124 -126 -127 -128 -128 -127 -126 -124 -120 -115 -107 -97
/ state 3, clock 1, (0 -> -1)O
-85 -72 -59 -46 -35 -26 -19 -16 -16 -19 -26 -35 -46 -59 -72 -85
/ state 3, clock 2, (-1 -> 0)O
-97 -107 -115 -120 -124 -126 -127 -128 -128 -127 -126 -124 -120 -115 -107 -97
/ state 3, clock 3, (0 -> -1)O
-85 -72 -59 -46 -35 -26 -19 -16 -16 -19 -26 -35 -46 -59 -72 -85
/ State Change portion
/ After each 16 waveform samples (64 clocks), A state lookup is performed
/ to get the correct phasor rotation for the next bit. If the next bit
/ is a '1', we want to rotate in the same direction. If the next bit is
/ a '0', we want to rotate in the opposite direction. I and Q states
/ are independent. The state entry is 4 bits of the form 'iiqq', where
/ 'ii' is the next I state and 'qq' is the next Q state. The basic pattern
/ (for Q states only) is:
/ CURRENT STATE
/ 0 1 2 3
/ ----------------------
/ Data bit = 0: Clock 0 | 2 3 2 3
/ Clock 1 | 2 3 2 3
/ Clock 2 | 3 2 2 3
/ Clock 3 | 3 2 2 3
/
/ Data bit = 1: Clock 0 | 0 1 0 1
/ Clock 1 | 0 1 0 1
/ Clock 2 | 0 1 1 0
/ Clock 3 | 0 1 1 0
/
/ The I state table is identical, but shifted by 1 clock period.
=256
/ Data bit = 0, Clock 0
22 23 22 23 32 33 32 33 22 23 22 23 32 33 32 33
/ Data bit = 0, Clock 1
32 33 32 33 22 23 22 23 22 23 22 23 32 33 32 33
/ Data bit = 0, Clock 2
33 32 32 33 23 22 22 23 23 22 22 23 33 32 32 33
/ Data bit = 0, Clock 3
23 22 22 23 33 32 32 33 23 22 22 23 33 32 32 33
=320
/ Data bit = 1, Clock 0
00 01 00 01 10 11 10 11 00 01 00 01 10 11 10 11
/ Data bit = 1, Clock 1
00 01 00 01 10 11 10 11 10 11 10 11 00 01 00 01
/ Data bit = 1, Clock 2
00 01 01 00 10 11 11 10 10 11 11 10 00 01 01 00
/ Data bit = 1, Clock 3
00 01 01 00 10 11 11 10 00 01 01 00 10 11 11 10
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