hack: also demod TCH_C1 uplinks

Author: schneider42

lib/burst_downmix_next_impl.cc

@@ -228,7 +228,10 @@ burst_downmix_next_impl::generate_sync_word(::iridium::direction direction)
     //std::vector<gr_complex> uw_dl = { s0, s1, s1, s1, s1, s0, s0, s0, s1, s0, s0, s1 };
     //std::vector<gr_complex> uw_dl = { s0, s0, s0, s0, s0, s1, s1, s0, s1, s1, s0, s1 s0, s1, s0, s1, s1, s0, s0, s1, s0, s1, s1, s1, s1, s0, s1, s1, s1, s0, s1, s0, s0};
     std::vector<gr_complex> uw_dl = { s1, s1, s0, s1, s1, s0, s1, s0, s1, s0, s1, s1 };//, s0, s0, s1, s0, s1, s1, s1, s1, s0, s1, s1, s1, s0, s1, s0, s0};
-    std::vector<gr_complex> uw_ul = { s1, s1, s0, s0, s0, s1, s0, s0, s1, s0, s1, s1 };
+                                    // 101 000 111 001 10001001
+    //std::vector<gr_complex> uw_ul = { s1, s0, s1, s0, s0, s0, s1, s1, s1, s0, s0, s1 };
+    // 01 00 00 00 10 10 00 11 10 01 10001001
+    std::vector<gr_complex> uw_ul = { s0, s1, s0, s0, s0, s0, s0, s0, s1, s0, s1, s0 };
     int i;
 
     if (direction == ::iridium::direction::DOWNLINK) {
@@ -653,7 +656,7 @@ int burst_downmix_next_impl::process_next_frame(float sample_rate,
     float correction;
     ::iridium::direction direction;
 
-    if (max_dl > max_ul || 1) {
+    if (max_dl > max_ul) {
         direction = ::iridium::direction::DOWNLINK;
         corr_offset = corr_offset_dl;
         correction = correction_dl;

lib/iridium.h

@@ -6,6 +6,7 @@ enum class direction {
     DOWNLINK = 1,
     UPLINK = 2,
     DOWNLINK_NEXT = 3,
+    UPLINK_NEXT = 4,
 };
 
 const int SYMBOLS_PER_SECOND = 25000;
@@ -28,4 +29,8 @@ const int UW_UL[] = { 2, 2, 0, 0, 0, 2, 0, 0, 2, 0, 2, 2 };
 
 //    std::vector<gr_complex> uw_dl = { s1, s1, s0, s1, s1, s0, s1, s0, s1, s0, s1, s1 };//, s0, s0, s1, s0, s1, s1, s1, s1, s0, s1, s1, s1, s0, s1, s0, s0};
 const int UW_DL_NEXT[] =             { 2,  2,  0,  2,  2,  0,  2,  0,  2,  0,  2, 2 };
+//    std::vector<gr_complex> uw_ul = { s1, s0, s1, s0, s0, s0, s1, s1, s1, s0, s0, s1 };
+//const int UW_UL_NEXT[] =             { 2,  0,  2,  0,  0,  2,  2,  2,  2,  0,  0, 2 };
+//    std::vector<gr_complex> uw_ul = { s0, s1, s0, s0, s0, s0, s0, s0, s1, s0, s1, s0 };
+const int UW_UL_NEXT[] =             { 0,  2,  0,  0,  0,  0,  0,  0,  2,  0,  2, 0 };
 } // namespace iridium

lib/iridium_qpsk_demod_impl.cc

@@ -306,6 +306,11 @@ bool iridium_qpsk_demod_impl::check_sync_word(int* demodulated_burst,
         uw_len = sizeof(::iridium::UW_DL) / sizeof(*::iridium::UW_DL);
     }
 
+    if (direction == ::iridium::direction::UPLINK_NEXT) {
+        uw = ::iridium::UW_UL_NEXT;
+        uw_len = sizeof(::iridium::UW_UL_NEXT) / sizeof(*::iridium::UW_UL_NEXT);
+    }
+
     int diffs = 0;
     for (int i = 0; i < uw_len; i++) {
         int diff = abs(demodulated_burst[i] - uw[i]);
@@ -390,9 +395,11 @@ void iridium_qpsk_demod_impl::handler(int channel, pmt::pmt_t msg)
         check_sync_word(d_demodulated_burst, n_symbols, ::iridium::direction::UPLINK);
     bool dl_next_uw_ok =
         check_sync_word(d_demodulated_burst, n_symbols, ::iridium::direction::DOWNLINK_NEXT);
+    bool ul_next_uw_ok =
+        check_sync_word(d_demodulated_burst, n_symbols, ::iridium::direction::UPLINK_NEXT);
     d_n_handled_bursts++;
 
-    if (!dl_uw_ok && !ul_uw_ok && !dl_next_uw_ok) {
+    if (!dl_uw_ok && !ul_uw_ok && !dl_next_uw_ok && !ul_next_uw_ok) {
         // Drop frames which have no valid sync word
         return;
     }