Add RTTY 8N2 support.

CMakeLists.txt

@@ -62,10 +62,17 @@ enable_testing()
      add_test(NAME test_horus_rtty_7n2
              COMMAND sh -c "cd ${CMAKE_CURRENT_BINARY_DIR}/src;
                             sox ${CMAKE_CURRENT_SOURCE_DIR}/samples/rtty_7n2.wav -r 48000 -t raw - |
-                            ./horus_demod -m rtty -c - - | grep OK | wc -l"
+                            ./horus_demod -c -m rtty - - | grep OK | wc -l"
               )
              set_tests_properties(test_horus_rtty_7n2 PROPERTIES PASS_REGULAR_EXPRESSION "6")
 
+     add_test(NAME test_horus_rtty_8n2
+             COMMAND sh -c "cd ${CMAKE_CURRENT_BINARY_DIR}/src;
+                            sox ${CMAKE_CURRENT_SOURCE_DIR}/samples/rtty_8n2.wav -r 48000 -t raw - |
+                            ./horus_demod -c --rate=300 -m rtty8n2 - - | grep OK | wc -l"
+              )
+             set_tests_properties(test_horus_rtty_8n2 PROPERTIES PASS_REGULAR_EXPRESSION "4")
+
      add_test(NAME test_horus_binary_iq
              COMMAND sh -c "cd ${CMAKE_CURRENT_BINARY_DIR}/src;
                             cat ${CMAKE_CURRENT_SOURCE_DIR}/samples/horusb_iq_s16.raw | 

horusdemodlib/__init__.py

@@ -1 +1 @@
-__version__ = "0.1.5"
+__version__ = "0.1.6"

horusdemodlib/demod.py

@@ -64,6 +64,7 @@ class Mode(Enum):
     BINARY_V1 = 0
     RTTY_7N2 = 90
     RTTY = 90
+    RTTY_8N2 = 91
     BINARY_V2_256BIT = 1
     BINARY_V2_128BIT = 2
 

horusdemodlib/payloads.py

@@ -98,11 +98,11 @@ def grab_latest_payload_id_list(url=PAYLOAD_ID_LIST_URL, local_file="payload_id_
     return True
 
 
-def init_payload_id_list():
+def init_payload_id_list(filename="payload_id_list.txt"):
     """ Initialise and update the local payload ID list. """
 
-    grab_latest_payload_id_list()
+    grab_latest_payload_id_list(local_file=filename)
-    HORUS_PAYLOAD_LIST = read_payload_list()
+    HORUS_PAYLOAD_LIST = read_payload_list(filename=filename)
 
 
 
@@ -171,10 +171,10 @@ def grab_latest_custom_field_list(url=HORUS_CUSTOM_FIELD_URL, local_file="custom
     return True
 
 
-def init_custom_field_list():
+def init_custom_field_list(filename="custom_field_list.json"):
     """ Initialise and update the local custom field list """
-    grab_latest_custom_field_list()
+    grab_latest_custom_field_list(local_file=filename)
-    HORUS_CUSTOM_FIELDS = read_custom_field_list()
+    HORUS_CUSTOM_FIELDS = read_custom_field_list(filename=filename)
 
 
 if __name__ == "__main__":

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "horusdemodlib"
-version = "0.1.5"
+version = "0.1.6"
 description = "Project Horus HAB Telemetry Demodulators"
 authors = ["Mark Jessop"]
 license = "LGPL-2.1-or-later"

src/horus_api.c

@@ -58,8 +58,12 @@ struct horus {
     int         total_payload_bits;  /* num bits rx-ed in last RTTY packet  */
 };
 
-/* Unique word for Horus RTTY 7 bit '$' character, 3 sync bits,
+
-   repeated 5 times */
+/*
+RTTY Unique word = $ characters, repeated at least 2 times.
+$ = (0)010 0100
+Reversed = 0010010(0)
+*/
 
 int8_t uw_horus_rtty_7N2[] = {
   0,0,1,0,0,1,0,1,1,0,
@@ -69,6 +73,14 @@ int8_t uw_horus_rtty_7N2[] = {
 //  0,0,1,0,0,1,0,1,1,0
 };
 
+int8_t uw_horus_rtty_8N2[] = {
+  0,0,1,0,0,1,0,0,1,1,0,
+  0,0,1,0,0,1,0,0,1,1,0,
+//  0,0,1,0,0,1,0,1,1,0,
+//  0,0,1,0,0,1,0,1,1,0,
+//  0,0,1,0,0,1,0,1,1,0
+};
+
 /* Unique word for Horus Binary V1 */
 
 int8_t uw_horus_binary_v1[] = {
@@ -104,7 +116,7 @@ struct horus *horus_open (int mode) {
 
 struct horus *horus_open_advanced (int mode, int Rs, int tx_tone_spacing) {
     int i, mask;
-    assert((mode == HORUS_MODE_RTTY_7N2) || (mode == HORUS_MODE_BINARY_V1) || (mode == HORUS_MODE_BINARY_V2_256BIT) || (mode == HORUS_MODE_BINARY_V2_128BIT));
+    assert((mode == HORUS_MODE_RTTY_7N2) || (mode == HORUS_MODE_RTTY_8N2) || (mode == HORUS_MODE_BINARY_V1) || (mode == HORUS_MODE_BINARY_V2_256BIT) || (mode == HORUS_MODE_BINARY_V2_128BIT));
 
     struct horus *hstates = (struct horus *)malloc(sizeof(struct horus));
     assert(hstates != NULL);
@@ -112,10 +124,10 @@ struct horus *horus_open_advanced (int mode, int Rs, int tx_tone_spacing) {
     hstates->Fs = 48000; hstates->Rs = Rs; hstates->verbose = 0; hstates->mode = mode;
 
     if (mode == HORUS_MODE_RTTY_7N2) {
-        // Parameter setup for RTTY Reception
+        // Parameter setup for RTTY 7N2 Reception
 
         hstates->mFSK = 2;
-        hstates->max_packet_len = HORUS_RTTY_NUM_BITS;
+        hstates->max_packet_len = HORUS_RTTY_7N2_NUM_BITS;
 
         // If baud rate not provided, use default
         if (hstates->Rs == -1){
@@ -140,6 +152,35 @@ struct horus *horus_open_advanced (int mode, int Rs, int tx_tone_spacing) {
         hstates->rx_bits_len = hstates->max_packet_len;
     }
 
+    if (mode == HORUS_MODE_RTTY_8N2) {
+        // Parameter setup for RTTY 8N2 Reception
+
+        hstates->mFSK = 2;
+        hstates->max_packet_len = HORUS_RTTY_8N2_NUM_BITS;
+
+        // If baud rate not provided, use default
+        if (hstates->Rs == -1){
+            hstates->Rs = HORUS_RTTY_DEFAULT_BAUD;
+        }
+
+        if (tx_tone_spacing == -1){
+            // No tone spacing provided. Use dummy value to keep fsk modem happy, and disable mask estimation.
+            tx_tone_spacing = 2*hstates->Rs;
+            mask = 0;
+        } else {
+            mask = 1;
+        }
+
+        /* map UW to make it easier to search for */
+
+        for (i=0; i<sizeof(uw_horus_rtty_8N2); i++) {
+            hstates->uw[i] = 2*uw_horus_rtty_8N2[i] - 1;
+        }        
+        hstates->uw_len = sizeof(uw_horus_rtty_8N2);
+        hstates->uw_thresh = sizeof(uw_horus_rtty_8N2) - 2;  /* allow a few bit errors in UW detection */
+        hstates->rx_bits_len = hstates->max_packet_len;
+    }
+
     if (mode == HORUS_MODE_BINARY_V1) {
         // Parameter setup for the Legacy Horus Binary Mode (22 byte frames, Golay encoding)
 
@@ -324,9 +365,9 @@ int hex2int(char ch) {
 }
 
 
-int extract_horus_rtty(struct horus *hstates, char ascii_out[], int uw_loc) {
+int extract_horus_rtty(struct horus *hstates, char ascii_out[], int uw_loc, int ascii_bits, int stop_bits) {
-    const int nfield = 7;                               /* 7 bit ASCII                    */
+    const int nfield = ascii_bits;                      /* 7 or 8 bit ASCII                    */
-    const int npad   = 3;                               /* 3 sync bits between characters */
+    const int npad   = stop_bits + 1;                   /* N stop bits + start bit between characters */
     int st = uw_loc;                                    /* first bit of first char        */
     int en = hstates->max_packet_len - nfield;          /* last bit of max length packet  */
 
@@ -375,7 +416,7 @@ int extract_horus_rtty(struct horus *hstates, char ascii_out[], int uw_loc) {
                 fprintf(stderr, "  begin endpacket\n");
             }
             // Only process up to the next 5 characters (checksum + line ending)
-            en = i + 10*5;
+            en = i + (ascii_bits+stop_bits+1)*5;
         }
 
         /* build up output array, really only need up to tx crc but
@@ -402,7 +443,7 @@ int extract_horus_rtty(struct horus *hstates, char ascii_out[], int uw_loc) {
         *(ptx_crc+4) = 0;  /* terminate ASCII string */
 
         if (crc_ok) {
-            hstates->total_payload_bits = strlen(ascii_out)*7;
+            hstates->total_payload_bits = strlen(ascii_out)*ascii_bits;
         }
     }
     else {
@@ -703,7 +744,20 @@ int horus_rx(struct horus *hstates, char ascii_out[], short demod_in[], int quad
            a packet, so lets try to extract valid packets */
 
         if (hstates->mode == HORUS_MODE_RTTY_7N2) {
-            packet_detected = extract_horus_rtty(hstates, ascii_out, uw_loc);
+            packet_detected = extract_horus_rtty(hstates, ascii_out, uw_loc, 7, 2);
+
+            if (packet_detected){
+                // If we have found a packet, advance the bits enough that we don't detect the
+                // same packet again, if it has more than 2x $$s.
+                // NEED TO CHECK THIS DOESN'T CAUSE SEGFAULTS!
+                for(i=0,j=100; i<100; i++,j++) {
+                    hstates->rx_bits[i] = hstates->rx_bits[j];
+                    hstates->soft_bits[i] = hstates->soft_bits[j];
+                }
+            }
+        }
+        if (hstates->mode == HORUS_MODE_RTTY_8N2) {
+            packet_detected = extract_horus_rtty(hstates, ascii_out, uw_loc, 8, 2);
 
             if (packet_detected){
                 // If we have found a packet, advance the bits enough that we don't detect the
@@ -766,6 +820,9 @@ int horus_get_max_ascii_out_len(struct horus *hstates) {
     if (hstates->mode == HORUS_MODE_RTTY_7N2) {
         return hstates->max_packet_len/10;     /* 7 bit ASCII, plus 3 sync bits */
     }
+    if (hstates->mode == HORUS_MODE_RTTY_8N2) {
+        return hstates->max_packet_len/11;     /* 8 bit ASCII, plus 3 sync bits */
+    }
     if (hstates->mode == HORUS_MODE_BINARY_V1) {
         return (HORUS_BINARY_V1_NUM_UNCODED_PAYLOAD_BYTES*2+1);     /* Hexadecimal encoded */
     }

src/horus_api.h

@@ -40,7 +40,7 @@
 #define HORUS_MODE_BINARY_V2_256BIT     1  // New 256-bit LDPC-encoded mode
 #define HORUS_MODE_BINARY_V2_128BIT     2  // New 128-bit LDPC-encoded mode
 #define HORUS_MODE_RTTY_7N2             90 // RTTY Decoding - 7N2
-#define HORUS_MODE_RTTY_8N2             90 // RTTY Decoding - 8N2
+#define HORUS_MODE_RTTY_8N2             91 // RTTY Decoding - 8N2
 
 
 // Settings for Legacy Horus Binary Mode (Golay Encoding)
@@ -65,7 +65,9 @@
 #define HORUS_BINARY_V2_128BIT_DEFAULT_TONE_SPACING            270 
 
 // Settings for RTTY Decoder
-#define HORUS_RTTY_NUM_BITS                     1000   // Limit the RTTY decoder to 100 characters per line (frame).
+#define HORUS_RTTY_MAX_CHARS                    120
+#define HORUS_RTTY_7N2_NUM_BITS                 (HORUS_RTTY_MAX_CHARS*10)
+#define HORUS_RTTY_8N2_NUM_BITS                 (HORUS_RTTY_MAX_CHARS*11)
 #define HORUS_RTTY_DEFAULT_BAUD                 100
 
 struct horus;

src/horus_demod.c

@@ -84,6 +84,9 @@ int main(int argc, char *argv[]) {
                 if ((strcmp(optarg, "RTTY") == 0) || (strcmp(optarg, "rtty") == 0)) {
                     mode = HORUS_MODE_RTTY_7N2;
                 }
+                if ((strcmp(optarg, "RTTY8N2") == 0) || (strcmp(optarg, "rtty8n2") == 0)) {
+                    mode = HORUS_MODE_RTTY_8N2;
+                }
                 if ((strcmp(optarg, "BINARY") == 0) || (strcmp(optarg, "binary") == 0)) {
                     mode = HORUS_MODE_BINARY_V1;
                 }