mirror of https://github.com/F5OEO/rpitx
Merge pull request #186 from cuddlycheetah/master
Added numeric pocsag mode
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F5OEO
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e8796bce41
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@ -22,8 +22,9 @@ SOFTWARE.
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Fork and modification for rpitx (c)(F5OEO 2018)
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*/
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** 11.09.2019 : Added Numeric Pager support by cuddlycheetah (github.com/cuddlycheetah)
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdint.h>
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@ -33,7 +34,7 @@ Fork and modification for rpitx (c)(F5OEO 2018)
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#include <unistd.h>
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#include "../librpitx/src/librpitx.h"
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#define PROGRAM_VERSION "0.1"
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#define PROGRAM_VERSION "0.2"
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//Check out main() at the bottom of the file
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//You can modify MIN_DELAY and MAX_DELAY to fit your needs.
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@ -84,6 +85,9 @@ Fork and modification for rpitx (c)(F5OEO 2018)
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//As mentioned above, characters are 7 bit ASCII encoded
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#define TEXT_BITS_PER_CHAR 7
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#define NUMERIC_BITS_PER_WORD 20
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#define NUMERIC_BITS_PER_DIGIT 4
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//Length of CRC codes in bits
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#define CRC_BITS 10
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@ -225,6 +229,107 @@ uint32_t encodeASCII(uint32_t initial_offset, char* str, uint32_t* out) {
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return numWordsWritten;
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}
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// Char Translationtable
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char* mirrorTab = new char[10]{ 0x00, 0x08, 0x04, 0x0c, 0x02, 0x0a, 0x06, 0x0e, 0x01, 0x09 };
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char encodeDigit(char ch) {
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if (ch >= '0' && ch <= '9')
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return mirrorTab[ch - '0'];
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switch (ch) {
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case ' ':
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return 0x03;
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case 'u':
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case 'U':
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return 0x0d;
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case '-':
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case '_':
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return 0x0b;
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case '(':
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case '[':
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return 0x0f;
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case ')':
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case ']':
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return 0x07;
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}
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return 0x05;
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}
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uint32_t encodeNumeric(uint32_t initial_offset, char* str, uint32_t* out) {
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//Number of words written to *out
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uint32_t numWordsWritten = 0;
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//Data for the current word we're writing
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uint32_t currentWord = 0;
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//Nnumber of bits we've written so far to the current word
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uint32_t currentNumBits = 0;
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//Position of current word in the current batch
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uint32_t wordPosition = initial_offset;
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while (*str != 0) {
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unsigned char c = *str;
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str++;
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//Encode the digit bits backwards
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for (int i = 0; i < NUMERIC_BITS_PER_DIGIT; i++) {
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currentWord <<= 1;
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char digit = encodeDigit(c);
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digit = ((digit & 1) <<3) |
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((digit & 2) <<1) |
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((digit & 4) >>1) |
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((digit & 8)>>3);
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currentWord |= (digit >> i) & 1;
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currentNumBits++;
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if (currentNumBits == NUMERIC_BITS_PER_WORD) {
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//Add the MESSAGE flag to our current word and encode it.
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*out = encodeCodeword(currentWord | FLAG_MESSAGE);
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out++;
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currentWord = 0;
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currentNumBits = 0;
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numWordsWritten++;
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wordPosition++;
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if (wordPosition == BATCH_SIZE) {
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//We've filled a full batch, time to insert a SYNC word
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//and start a new one.
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*out = SYNC;
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out++;
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numWordsWritten++;
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wordPosition = 0;
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}
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}
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}
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}
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//Write remainder of message
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if (currentNumBits > 0) {
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//Pad out the word to 20 bits with zeroes
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currentWord <<= 20 - currentNumBits;
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*out = encodeCodeword(currentWord | FLAG_MESSAGE);
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out++;
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numWordsWritten++;
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wordPosition++;
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if (wordPosition == BATCH_SIZE) {
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//We've filled a full batch, time to insert a SYNC word
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//and start a new one.
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*out = SYNC;
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out++;
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numWordsWritten++;
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wordPosition = 0;
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}
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}
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return numWordsWritten;
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}
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/**
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* An address of 21 bits, but only 18 of those bits are encoded in the address
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* word itself. The remaining 3 bits are derived from which frame in the batch
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@ -241,6 +346,7 @@ int addressOffset(int address) {
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* (*message) is a null terminated C string.
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* (*out) is the destination to which the transmission will be written.
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*/
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bool numeric = false;
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void encodeTransmission(int address, int fb, char* message, uint32_t* out) {
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@ -273,8 +379,12 @@ void encodeTransmission(int address, int fb, char* message, uint32_t* out) {
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out++;
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//Encode the message itself
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out += encodeASCII(addressOffset(address) + 1, message, out);
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if (numeric == true) {
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out += encodeNumeric(addressOffset(address) + 1, message, out);
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} else {
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out += encodeASCII(addressOffset(address) + 1, message, out);
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}
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//Finally, write an IDLE word indicating the end of the message
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*out = IDLE;
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@ -325,6 +435,41 @@ size_t textMessageLength(int address, int numChars) {
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return numWords;
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}
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/**
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* Calculates the length in words of a numeric POCSAG message, given the address
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* and the number of characters to be transmitted.
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*/
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size_t numericMessageLength(int address, int numChars) {
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size_t numWords = 0;
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//Padding before address word.
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numWords += addressOffset(address);
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//Address word itself
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numWords++;
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//numChars * 7 bits per character / 20 bits per word, rounding up
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numWords += (numChars * NUMERIC_BITS_PER_DIGIT + (NUMERIC_BITS_PER_WORD - 1))
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/ NUMERIC_BITS_PER_WORD;
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//Idle word representing end of message
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numWords++;
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//Pad out last batch with idles
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numWords += BATCH_SIZE - (numWords % BATCH_SIZE);
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//Batches consist of 16 words each and are preceded by a sync word.
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//So we add one word for every 16 message words
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numWords += numWords / BATCH_SIZE;
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//Preamble of 576 alternating 1,0,1,0 bits before the message
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//Even though this comes first, we add it to the length last so it
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//doesn't affect the other word-based calculations
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numWords += PREAMBLE_LENGTH / 32;
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return numWords;
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}
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void SendFsk(uint64_t Freq,bool Inverted,int SR,bool debug,uint32_t *Message,int Size)
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{
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@ -375,6 +520,7 @@ Usage:\npocsag [-f Frequency] [-i] [-r Rate]\n\
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-f float central frequency Hz(50 kHz to 1500 MHz),\n\
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-r int baud rate (512, 1200 or 2400. Default 1200 bps),\n\
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-b int function bits (0-3. Default 3),\n\
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-n use numeric messages,\n\
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-i invert the modulation polarity,\n\
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-d debug,\n\
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-? help (this help).\n\
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@ -391,14 +537,14 @@ int main(int argc, char* argv[]) {
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//from 1-10 seconds in length, to act as a simulated "delay".
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int a;
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int anyargs = 1;
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uint64_t SetFrequency=439875000L;
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uint64_t SetFrequency=466230000L;
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int SetRate = 1200;
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int SetFunctionBits = 3;
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bool SetInverted = false;
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bool debug = false;
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while(1)
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{
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a = getopt(argc, argv, "b:df:ir:");
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a = getopt(argc, argv, "b:dnf:ir:");
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if(a == -1)
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{
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@ -409,7 +555,10 @@ int main(int argc, char* argv[]) {
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switch(a)
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{
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case 'n': // Numeric messages
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numeric = true;
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break;
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case 'd': // Debug
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debug = true;
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break;
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@ -505,7 +654,9 @@ int main(int argc, char* argv[]) {
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}
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size_t messageLength = textMessageLength(address, strlen(message));
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size_t messageLength = numeric
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? numericMessageLength(address, strlen(message))
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: textMessageLength(address, strlen(message));
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uint32_t* transmission =
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(uint32_t*) malloc(sizeof(uint32_t) * messageLength+2);
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