WIP qam16c2, ofdm_mod runs but doesn't decode in Octave

2024-04-04 09:16:21 +10:30 · 2024-04-04 09:16:21 +10:30 · 4726a97450
parent 6a5687c5f5
commit 4726a97450
5 changed files with 50 additions and 22 deletions
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@ -472,7 +472,7 @@ endif()

    add_test(NAME test_OFDM_modem_octave_qam16_uncoded
             COMMAND sh -c "cd ${CMAKE_CURRENT_SOURCE_DIR}/octave;
-                            echo \"ofdm_tx('test_qam16.raw','qam16c1',3,12,'awgn','bursts',3); ofdm_rx('test_qam16.raw','qam16c1', 'passber', 0.05, 'packetsperburst', 1); quit\" |
+                            echo \"ofdm_tx('test_qam16.raw','qam16c2',1,12,'awgn','bursts',3); ofdm_rx('test_qam16.raw','qam16c2', 'passber', 0.05, 'packetsperburst', 1); quit\" |
                            DISPLAY=\"\" octave-cli")
             set_tests_properties(test_OFDM_modem_octave_qam16_uncoded PROPERTIES PASS_REGULAR_EXPRESSION "Pass")

--- a/octave/ofdm_lib.m
+++ b/octave/ofdm_lib.m
@ -76,7 +76,7 @@ function states = ofdm_init(config)
    1 + j,  1 + j*3,  3 + j,  3 + j*3;
    1 - j,  1 - j*3,  3 - j,  3 - j*3;
   -1 + j, -1 + j*3, -3 + j, -3 + j*3;
-   -1 - j, -1 - j*3, -3 - j, -3 - j*3]/3;
+   -1 - j, -1 - j*3, -3 - j, -3 - j*3];
  rms = sqrt(states.qam16(:)'*states.qam16(:)/16);% set average Es to 1
  states.qam16 /= rms;
  states.qam16 *= exp(-j*pi/4);                   % same rotation as QPSK constellation
--- a/src/ofdm.c
+++ b/src/ofdm.c
@ -75,13 +75,22 @@ static void ofdm_demod_core(struct OFDM *, int *);
 */
 static const complex float qpsk[] = {1.0f + 0.0f * I, 0.0f + 1.0f * I,
                                     0.0f - 1.0f * I, -1.0f + 0.0f * I};
-
+/*
 static const complex float qam16[] = {
    1.0f + 1.0f * I,  1.0f + 3.0f * I,  3.0f + 1.0f * I,  3.0f + 3.0f * I,
    1.0f - 1.0f * I,  1.0f - 3.0f * I,  3.0f - 1.0f * I,  3.0f - 3.0f * I,
    -1.0f + 1.0f * I, -1.0f + 3.0f * I, -3.0f + 1.0f * I, -3.0f + 3.0f * I,
    -1.0f - 1.0f * I, -1.0f - 3.0f * I, -3.0f - 1.0f * I, -3.0f - 3.0f * I};
-
+*/
+static const complex float qam16[] = {
+    4.4721e-01 + 2.7756e-17 * I,  8.9443e-01 + 4.4721e-01 * I,
+    8.9443e-01 - 4.4721e-01 * I,  1.3416e+00 + 1.1102e-16 * I,
+    2.7756e-17 - 4.4721e-01 * I,  -4.4721e-01 - 8.9443e-01 * I,
+    4.4721e-01 - 8.9443e-01 * I,  1.1102e-16 - 1.3416e+00 * I,
+    -2.7756e-17 + 4.4721e-01 * I, 4.4721e-01 + 8.9443e-01 * I,
+    -4.4721e-01 + 8.9443e-01 * I, -1.1102e-16 + 1.3416e+00 * I,
+    -4.4721e-01 - 2.7756e-17 * I, -8.9443e-01 - 4.4721e-01 * I,
+    -8.9443e-01 + 4.4721e-01 * I, -1.3416e+00 - 1.1102e-16 * I};
 /*
 * These pilots are compatible with Octave version
 */
@ -468,12 +477,12 @@ struct OFDM *ofdm_create(const struct OFDM_CONFIG *config) {
      MALLOC(sizeof(complex float) * (ofdm->nuwbits / ofdm->bps));
  assert(ofdm->tx_uw_syms != NULL);

-  assert(ofdm->bps == 2);  // TODO generalise
-  for (int s = 0; s < (ofdm->nuwbits / ofdm->bps); s++) {
-    int dibit[2];
-    dibit[1] = ofdm->tx_uw[2 * s];
-    dibit[0] = ofdm->tx_uw[2 * s + 1];
-    ofdm->tx_uw_syms[s] = qpsk_mod(dibit);
+  for (int b = 0, s = 0; b < ofdm->nuwbits; b += ofdm->bps, s++) {
+    int bits[ofdm->bps];
+    for (int i = 0; i < ofdm->bps; i++)
+      bits[ofdm->bps - 1 - i] = ofdm->tx_uw[b + i];
+    if (ofdm->bps == 2) ofdm->tx_uw_syms[s] = qpsk_mod(bits);
+    if (ofdm->bps == 4) ofdm->tx_uw_syms[s] = qam16_mod(bits);
  }

  /* sync state machine */
@ -1208,7 +1217,14 @@ void ofdm_mod(struct OFDM *ofdm, COMP *result, const int *tx_bits) {

      tx_sym_lin[i] = qpsk_mod(dibit);
    }
-  } /* else if (ofdm->bps == 3) { } TODO */
+  } else if (ofdm->bps == 4) {
+    for (int b = 0, s = 0; b < ofdm->bitsperpacket; b += ofdm->bps, s++) {
+      int bits[ofdm->bps];
+      for (int i = 0; i < ofdm->bps; i++)
+        bits[ofdm->bps - 1 - i] = tx_bits[b + i] & 0x1;
+      tx_sym_lin[s] = qam16_mod(bits);
+    }
+  }

  ofdm_txframe(ofdm, tx, tx_sym_lin);
 }
@ -2436,10 +2452,6 @@ void ofdm_assemble_qpsk_modem_packet_symbols(struct OFDM *ofdm,
  int p = 0;
  int u = 0;

-  assert(
-      ofdm->bps ==
-      2); /* this only works for QPSK at this stage (e.g. modem packet mod) */
-
  for (s = 0; s < (Nsymsperpacket - Ntxtsyms); s++) {
    if ((u < Nuwsyms) && (s == ofdm->uw_ind_sym[u])) {
      modem_packet[s] = ofdm->tx_uw_syms[u++];
@ -2451,6 +2463,8 @@ void ofdm_assemble_qpsk_modem_packet_symbols(struct OFDM *ofdm,
  assert(u == Nuwsyms);
  assert(p == (Nsymsperpacket - Nuwsyms - Ntxtsyms));

+  /* txt bit insertion only works for QPSK at this stage */
+  assert((Ntxtsyms == 0) || (ofdm->bps == 2));
  for (t = 0; s < Nsymsperpacket; s++, t += 2) {
    dibit[1] = txt_bits[t] & 0x1;
    dibit[0] = txt_bits[t + 1] & 0x1;
--- a/src/ofdm_internal.h
+++ b/src/ofdm_internal.h
@ -46,7 +46,7 @@ extern "C" {

 #define TAU (2.0f * M_PI)
 #define ROT45 (M_PI / 4.0f)
-#define MAX_UW_BITS 64
+#define MAX_UW_BITS 192

 #define cmplx(value) (cosf(value) + sinf(value) * I)
 #define cmplxconj(value) (cosf(value) + sinf(value) * -I)
--- a/src/ofdm_mode.c
+++ b/src/ofdm_mode.c
@ -42,6 +42,7 @@ void ofdm_init_mode(char mode[], struct OFDM_CONFIG *config) {
  config->state_machine = "voice1";
  config->data_mode = "";
  config->codename = "HRA_112_112";
+  config->EsNodB = 3.0;
  config->clip_gain1 = 2.5;
  config->clip_gain2 = 0.8;
  config->clip_en = true;
@ -92,23 +93,36 @@ void ofdm_init_mode(char mode[], struct OFDM_CONFIG *config) {
    config->state_machine = "voice2";
    config->ftwindowwidth = 64;
    config->foff_limiter = true;
-  } else if (strcmp(mode, "qam16") == 0) {
-    /* not in use yet */
+  } else if (strcmp(mode, "qam16c2") == 0) {
    config->ns = 5;
-    config->np = 5;
+    config->np = 31;
    config->tcp = 0.004;
    config->ts = 0.016;
    config->nc = 33;
    config->bps = 4;
    config->txtbits = 0;
-    config->nuwbits = 15 * 4;
-    config->bad_uw_errors = 5;
-    config->ftwindowwidth = 32;
+    config->nuwbits = 42 * 4;
+    assert(config->nuwbits <= MAX_UW_BITS);
+    config->bad_uw_errors = 15;
+    config->ftwindowwidth = 80;
    config->state_machine = "data";
    config->amp_est_mode = 1;
    config->tx_bpf_en = false;
    config->clip_en = false;
    config->data_mode = "streaming";
+    config->amp_scale = 135E3;
+    config->clip_en = false;
+    config->tx_bpf_en = false;
+    config->rx_bpf_en = false;
+
+    uint8_t uw[] = {1, 1, 0, 0, 1, 0, 1, 0, 1, 1, 1, 1,
+                    0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0};
+    memset(config->tx_uw, 0, config->nuwbits);
+    memcpy(config->tx_uw, uw, sizeof(uw));
+    memcpy(&config->tx_uw[config->nuwbits - sizeof(uw)], uw, sizeof(uw));
+
+    config->EsNodB = 10;
+    config->codename = "H_16200_9720";
  } else if (strcmp(mode, "datac0") == 0) {
    config->ns = 5;
    config->np = 4;