FT8 demod: support for types 0.5 and 5 messages

ft8/unpack.cpp

@@ -145,11 +145,8 @@ std::string Packing::unpackcall(int x)
 // unpack a 15-bit grid square &c.
 // 77-bit version, from inspection of packjt77.f90.
 // ir is the bit after the two 28+1-bit callee/caller.
-// i3 is the message type, usually 1.
-std::string Packing::unpackgrid(int ng, int ir, int i3)
+std::string Packing::unpackgrid15(int ng, int ir)
 {
-    (void) i3;
-
     if (ng < NGBASE)
     {
         // maidenhead grid system:
@@ -203,6 +200,31 @@ std::string Packing::unpackgrid(int ng, int ir, int i3)
     return std::string(tmp);
 }
 
+std::string Packing::unpackgrid25(int ng)
+{
+    int x1 = ng / (18 * 10 * 10 * 25 * 25);
+    ng %= (18 * 10 * 10 * 25 * 25);
+    int x2 = ng / (10 * 10 * 25 * 25);
+    ng %= (10 * 10 * 25 * 25);
+    int x3 = ng / (10 * 25 * 25);
+    ng %= (10 * 25 * 25);
+    int x4 = ng / (25 * 25);
+    ng %= (25 * 25);
+    int x5 = ng / (25);
+    ng %= (25);
+    int x6 = ng;
+    char tmp[7];
+    tmp[0] = 'A' + x1;
+    tmp[1] = 'A' + x2;
+    tmp[2] = '0' + x3;
+    tmp[3] = '0' + x4;
+    tmp[4] = 'A' + x5;
+    tmp[5] = 'A' + x6;
+    tmp[6] = '\0';
+
+    return std::string(tmp);
+}
+
 void Packing::remember_call(std::string call)
 {
     hashes_mu.lock();
@@ -329,7 +351,7 @@ std::string Packing::unpack_1(int a77[], std::string& call1str, std::string& cal
 
     call1str = trim(unpackcall(call1));
     call2str = trim(unpackcall(call2));
-    locstr = unpackgrid(grid, ir, i3);
+    locstr = unpackgrid15(grid, ir);
 
     remember_call(call1str);
     remember_call(call2str);
@@ -339,6 +361,52 @@ std::string Packing::unpack_1(int a77[], std::string& call1str, std::string& cal
     return call1str + (rover1 ? pr : "") + " " + call2str + (rover2 ? pr : "") + " " + locstr;
 }
 
+std::string Packing::unpack_5(int a77[], std::string& call1str, std::string& call2str, std::string& locstr)
+{
+    int x12 = un64(a77, 0, 12);
+    // 12-bit hash
+    hashes_mu.lock();
+    std::string ocall;
+
+    if (hashes12.count(x12) > 0) {
+        ocall = hashes12[x12];
+    } else {
+        ocall = "<...12>";
+    }
+
+    call1str = std::string(ocall);
+
+    int x22 = un64(a77, 12, 22);
+
+    if (hashes22.count(x22) > 0) {
+        ocall = hashes12[x22];
+    } else {
+        ocall = "<...22>";
+    }
+
+    call2str = std::string(ocall);
+
+    // mext bit is alway for R
+    int i = 12+ 22 +1;
+    // r3
+    int rst = un64(a77, i, 3);
+    rst = 52 + 10 * rst;
+    i += 3;
+    int qsonb = un64(a77, i, 11);
+    char report[16];
+    sprintf(report, "%d%04d", rst, qsonb);
+    i += 11;
+    // g25
+    int ng = un64(a77, i, 25);
+    locstr = unpackgrid25(ng);
+
+    std::string msg;
+    msg = call1str + " " + call2str + " " + std::string(report) + " " + locstr;
+    call1str += " " + std::string(report);
+
+    return msg;
+}
+
 // free text
 // 71 bits, 13 characters, each one of 42 choices.
 // reversed.
@@ -408,6 +476,30 @@ std::string Packing::unpack_0_1(int a77[], std::string& call1str, std::string& c
     return msg;
 }
 
+std::string Packing::unpack_0_5(int a77[], std::string& call1str, std::string& call2str, std::string& locstr)
+{
+    (void) call2str;
+    (void) locstr;
+
+    const char *cc = "0123456789ABCDEF";
+    std::string msg = "123456789ABCDEF012";
+
+    // first digit is on 3 bits
+    int d0 = un64(a77, 0, 3);
+    msg[17] = cc[d0];
+    // 17 hexadecimal digits = 17*4 = 68 bits
+    boost::multiprecision::int128_t x = un128(a77, 3, 68);
+
+    for (int i = 0; i < 17; i++)
+    {
+        msg[17 - 1 - i] = cc[(int) (x % 4)];
+        x = x / 4;
+    }
+
+    call1str = msg;
+    return msg;
+}
+
 // ARRL RTTY Round-Up states/provinces
 const char *Packing::ru_states[] = {
     "AL", "AK", "AZ", "AR", "CA", "CO", "CT", "DE", "FL", "GA",
@@ -589,6 +681,12 @@ std::string Packing::unpack(int a77[], std::string& call1, std::string& call2, s
         return unpack_0_3(a77, n3, call1, call2, loc);
     }
 
+    if (i3 == 0 && n3 == 5)
+    {
+        // telemetry
+        return unpack_0_5(a77, call1, call2, loc);
+    }
+
     if (i3 == 1 || i3 == 2)
     {
         // ordinary message or EU VHF
@@ -607,7 +705,11 @@ std::string Packing::unpack(int a77[], std::string& call1, std::string& call2, s
         return unpack_4(a77, call1, call2, loc);
     }
 
-    // TODO: i3 == 5 EU VHF missing
+    if (i3 == 5)
+    {
+        // EU VHF with 6 digits locator
+        return unpack_5(a77, call1, call2, loc);
+    }
 
     call1 = "UNK";
     sprintf(tmp, "UNK i3=%d n3=%d", i3, n3);

ft8/unpack.h

@@ -38,16 +38,19 @@ public:
 private:
     static int ihashcall(std::string call, int m);
     std::string unpackcall(int x);
-    std::string unpackgrid(int ng, int ir, int i3);
+    std::string unpackgrid15(int ng, int ir);
+    std::string unpackgrid25(int ng);
     void remember_call(std::string call);
     std::string unpack_0_0(int a77[], std::string& call1str, std::string& call2str, std::string& locstr);
     std::string unpack_0_1(int a77[], std::string& call1str, std::string& call2str, std::string& locstr);
     // 0.3 and 0.4
     std::string unpack_0_3(int a77[], int n3, std::string& call1str, std::string& call2str, std::string& locstr);
+    std::string unpack_0_5(int a77[], std::string& call1str, std::string& call2str, std::string& locstr);
     // 1 and 2
     std::string unpack_1(int a77[], std::string& call1str, std::string& call2str, std::string& locstr);
     std::string unpack_3(int a77[], std::string& call1str, std::string& call2str, std::string& locstr);
     std::string unpack_4(int a77[], std::string& call1str, std::string& call2str, std::string& locstr);
+    std::string unpack_5(int a77[], std::string& call1str, std::string& call2str, std::string& locstr);
 
     QRecursiveMutex hashes_mu;
     std::map<int, std::string> hashes10;

plugins/channelrx/demodft8/readme.md

@@ -154,9 +154,9 @@ Example:
   - **3**: SNR in 2.5 kHz bandwidth
   - **4**: Message start delay in seconds from standard sequence start
   - **5**: Message carrier shift from base frequency in Hz
-  - **6**: First callsign area. May contain spaces (ex: "CQ DX")
-  - **7**: Second callsign area
-  - **8**: Locator area
+  - **6**: First callsign area. May contain spaces (ex: "CQ DX"). Note that for messages types 0.1 and 5 it is slighlty different from the standard (See C.10)
+  - **7**: Second callsign area and is always a callsign. This might be slighlty different from the standard (see above)
+  - **8**: Locator area maybe a 4 or 6 digit locator, a report, acknowledgement (RRR) or a greetings (RR73, 73)
   - **9**: Decoder information if any
 
 The splitting and naming of files is different from WSJT-X scheme.
@@ -184,23 +184,23 @@ Displays the received messages in a table which columns are the following:
 
   - **UTC**: UTC time in HHmmss format of the FT8 slot
   - **Typ**: Message type according to the i3.n3 format described in the protocol (see reference at the top):
-    - **0.0**: Free text
-    - **0.1**: DXpedition. Message carries two compacted messages (one for RR73 and one for report to two different callees). They will be de-compacted for dispplay.
+    - **0.0**: Free text. The first call area is populated with the free text. second call and locator areas are left blank.
+    - **0.1**: DXpedition. Message carries two compacted messages (one for RR73 and one for report to two different callees). They will be de-compacted in two separate messages for display. This is different from the standard that yields a single message.
     - **0.3**: ARRL field day
     - **0.4**: ARRL field day
     - **0.5**: Telemetry
     - **1**: Standard message (the most common)
-    - **2**: European VHF (4 char locator) minor change to standard message
+    - **2**: European VHF (4 char locator) minor change to standard message above
     - **3**: Russian RTTY
     - **4**: Non standard call
-    - **5**: European VHF (6 char locator)
+    - **5**: European VHF (6 char locator). The report + QSO number is appended to first call area not to pollute the second call area which contains only a callsign, This is slightly diffrent from the standard.
   - **P**: LDPC decoder pass index that was successful (0 to 2) as there are 3 passes
   - **OKb**: Number of correct bits in the message before FEC correction. Maximum is 174 in which case no FEC would be needed.
   - **dt**: Message start time shift in seconds from standard FT8 time slot
   - **df**: Message frequency shift in Hz from base frequency. This is the shift of the lowest frequency symbol
   - **SNR**: Signal to noise ratio in dB transposed in a 2.5 kHz bandwidth (WSJT-X standard). The actual SNR is this value plus 26 dB.
-  - **Call1**: This is the first call area and may contain the caller callsign, a CQ or a custom 13 character message in which case the second call and locator areas are empty
-  - **Call2**: This is the second call area and will contain the callsign of the responding station
+  - **Call1**: This is the first call area and may contain the caller callsign, a CQ or a custom 13 character message in which case the second call and locator areas are empty. It may be slightly different from the standard for message type 5 (see above).
+  - **Call2**: This is the second call area and will contain the callsign of the responding station. This is always a callsign and this may differ slightly from the standard for messages type 5 (see above).
   - **Loc**: Locator area which contains the 4 character Maidenhead locator, a report, an acknowledgement (RRR) or a greetings (73 or RR73)
   - **Info**: FT8 decoder information if any. If OSD is active (see C.1.3) and OSD was activated it reports the OSD decoder status as `OSD-N-MM` where N is the OSD depth reached and MM is the number of correct LDPC bits.