shallow zip-file copy from codec2 e9d726bf20

1 files changed, 251 insertions, 0 deletions

diff --git a/octave/ofdm_rx.m b/octave/ofdm_rx.m
new file mode 100644
index 0000000..55e93cb
--- /dev/null
+++ b/octave/ofdm_rx.m
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+% ofdm_rx.m
+% David Rowe May 2018
+%
+% OFDM file based uncoded rx to unit test core OFDM modem.  See also
+% ofdm_ldpc_rx which includes LDPC and interleaving, and ofdm_demod.c
+
+#{
+    1. Streaming mode operation:
+  
+       ofdm_rx("test_datac0.raw","datac0")
+    
+    2. Burst mode, tell state machine there is one packet in each burst:
+    
+       ofdm_rx("test_datac0.raw","datac0","packetsperburst",1)
+       
+    3. Burst mode, enable only postamble detecion:
+    
+       ofdm_rx("test_datac0.raw","datac0","packetsperburst",1, "postambletest")
+#}
+
+function ofdm_rx(filename, mode="700D", varargin)
+  ofdm_lib;
+  more off;
+  pkg load signal;
+  
+  % init modem
+
+  config = ofdm_init_mode(mode);
+  states = ofdm_init(config);
+  print_config(states);
+  ofdm_load_const;
+  states.verbose = 0;
+  pass_ber = 0;
+  pass_packet_count = 0;
+   
+  i = 1;
+  while i <= length(varargin)
+    if strcmp(varargin{i},"packetsperburst")
+      states.data_mode = "burst"; % use pre/post amble based sync
+      states.packetsperburst = varargin{i+1}; i++;
+      states.postambledetectoren = 1;
+    elseif strcmp(varargin{i},"passber")
+      pass_ber = varargin{i+1}; i++;
+    elseif strcmp(varargin{i},"passpacketcount")
+      pass_packet_count = varargin{i+1}; i++;
+    elseif strcmp(varargin{i},"postambletest")
+      printf("postamble test!\n");
+      states.postambletest = 1;
+      % at high SNR avoid firing on data frames just before postamble
+      states.timing_mx_thresh = 0.15;
+    else
+      printf("\nERROR unknown argument: %s\n", varargin{i});
+      return;
+    end
+    i++; 
+  end
+  
+  % load real samples from file
+
+  Ascale = states.amp_scale/2; % as input is a real valued signal
+  frx=fopen(filename,"rb"); rx = fread(frx, Inf, "short")/Ascale; fclose(frx);
+  Nsam = length(rx);  prx = 1;
+
+  % OK re-generate tx frame for BER calcs
+
+  tx_bits = create_ldpc_test_frame(states, coded_frame=0);
+
+  % init logs and BER stats
+
+  rx_np_log = []; timing_est_log = []; delta_t_log = []; foff_est_hz_log = [];
+  sample_point_log = [];
+  channel_est_pilot_log = []; snr_log = [];
+  Terrs = Tbits = Terrs_coded = Tbits_coded = Tpackets = Tpacketerrs = 0;
+  packet_count = frame_count = 0;
+  Nerrs_coded_log = Nerrs_log = [];
+  error_positions = [];
+
+  prx = 1;
+  nin = Nsamperframe+2*(M+Ncp);
+  states.verbose = 1;
+  Nsymsperpacket = Nbitsperpacket/bps; Nsymsperframe = Nbitsperframe/bps;
+  rx_syms = zeros(1,Nsymsperpacket); rx_amps = zeros(1,Nsymsperpacket);
+  Nerrs = 0; rx_uw = zeros(1,states.Nuwbits);
+
+  % main loop ----------------------------------------------------------------
+  
+  f = 1;
+  while(prx < Nsam)
+    
+    % insert samples at end of buffer, set to zero if no samples
+    % available to disable phase estimation on future pilots on last
+    % frame of simulation
+
+    lnew = min(Nsam-prx,states.nin);
+    rxbuf_in = zeros(1,states.nin);
+
+    if lnew
+      rxbuf_in(1:lnew) = rx(prx:prx+lnew-1);
+    end
+    prx += states.nin;
+
+    if states.verbose
+      printf("f: %3d nin: %4d st: %-6s ", f, states.nin, states.sync_state);
+    end
+
+    if strcmp(states.sync_state,'search')
+      [timing_valid states] = ofdm_sync_search(states, rxbuf_in);
+    else
+      % accumulate a buffer of data symbols for this packet
+      rx_syms(1:end-Nsymsperframe) = rx_syms(Nsymsperframe+1:end);
+      rx_amps(1:end-Nsymsperframe) = rx_amps(Nsymsperframe+1:end);
+      [states rx_bits achannel_est_pilot_log arx_np arx_amp] = ofdm_demod(states, rxbuf_in);
+      rx_syms(end-Nsymsperframe+1:end) = arx_np;
+      rx_amps(end-Nsymsperframe+1:end) = arx_amp;
+
+      rx_uw = extract_uw(states, rx_syms(end-Nuwframes*Nsymsperframe+1:end), rx_amps(end-Nuwframes*Nsymsperframe+1:end));
+
+      % We need the full packet of symbols before disassembling and checking for bit errors
+      if states.modem_frame == (states.Np-1);
+        rx_bits = zeros(1,Nbitsperpacket);
+        for s=1:Nsymsperpacket
+          if bps == 2
+             rx_bits(bps*(s-1)+1:bps*s) = qpsk_demod(rx_syms(s));
+          elseif bps == 4
+             rx_bits(bps*(s-1)+1:bps*s) = qam16_demod(states.qam16,rx_syms(s), rx_amps(s));
+          end
+        end
+
+        errors = xor(tx_bits, rx_bits);
+        Nerrs = sum(errors);
+        Nerrs_log = [Nerrs_log Nerrs];
+        Terrs += Nerrs;
+        Tbits += Nbitsperpacket;
+        packet_count++;
+        
+        % per-packet SNR estimate
+        EsNo_estdB = esno_est_calc(rx_syms);
+        SNR_estdB = snr_from_esno(states, EsNo_estdB);
+        snr_log = [snr_log SNR_estdB];
+      end
+
+      % we are in sync so log states
+
+      rx_np_log = [rx_np_log arx_np];
+      timing_est_log = [timing_est_log states.timing_est];
+      sample_point_log = [sample_point_log states.sample_point];
+      delta_t_log = [delta_t_log states.delta_t];
+      foff_est_hz_log = [foff_est_hz_log states.foff_est_hz];
+      channel_est_pilot_log = [channel_est_pilot_log; achannel_est_pilot_log];
+
+      frame_count++;
+    end
+    
+    states = sync_state_machine(states, rx_uw);
+
+    if states.verbose
+      if strcmp(states.last_sync_state,'search') == 0
+        if (states.modem_frame == 0) && (strcmp(states.sync_state, "trial") == 0)
+          printf(" euw: %3d %d mf: %2d pbw: %s foff: %4.1f eraw: %3d snr: %5.2f",
+                 states.uw_errors, states.sync_counter, states.modem_frame, states.phase_est_bandwidth(1),
+                 states.foff_est_hz, Nerrs, SNR_estdB);
+        else
+          printf(" euw: %3d %d mf: %2d pbw: %s foff: %4.1f",
+                 states.uw_errors, states.sync_counter, states.modem_frame, states.phase_est_bandwidth(1),
+                 states.foff_est_hz);
+        end
+      end
+      printf("\n");
+    end
+
+    % reset stats if in streaming mode, don't reset if in burst mode
+    if strcmp(states.data_mode, "streaming") && states.sync_start
+      Nerrs_log = [];
+      Terrs = Tbits = frame_count = 0;
+      rx_np_log = [];
+      sig_var_log = []; noise_var_log = [];
+    end
+    
+    f++;
+  end
+  Nframes = f;
+
+  ber = Terrs/(Tbits+1E-12);
+  printf("\nBER..: %5.4f Tbits: %5d Terrs: %5d\n", ber, Tbits, Terrs);
+
+  % If we have enough frames, calc BER discarding first few frames where freq
+  % offset is adjusting
+
+  Ndiscard = 20;
+  if packet_count > Ndiscard
+    Terrs -= sum(Nerrs_log(1:Ndiscard)); Tbits -= Ndiscard*Nbitsperframe;
+    printf("BER2.: %5.4f Tbits: %5d Terrs: %5d\n", Terrs/Tbits, Tbits, Terrs);
+  end
+
+  SNR_estdB = mean(snr_log);
+  printf("Packets: %3d Npre: %d Npost: %d SNR3k: %3.2f\n",
+         packet_count, states.npre, states.npost, SNR_estdB);
+
+  figure(1); clf;
+  tmp = exp(j*pi/4)*rx_np_log(floor(end/4):floor(end-end/8));
+  plot(tmp,'+');
+  mx = 2*max(abs(tmp));
+  axis([-mx mx -mx mx]);
+  title('Scatter');
+
+  figure(2); clf;
+  plot(angle(channel_est_pilot_log(:,2:Nc)),'g+', 'markersize', 5);
+  title('Phase est');
+  axis([1 length(channel_est_pilot_log) -pi pi]);
+
+  figure(3); clf;
+  plot(abs(channel_est_pilot_log(:,:)),'g+', 'markersize', 5);
+  title('Amp est');
+  axis([1 length(channel_est_pilot_log) -3 3]);
+
+  figure(4); clf;
+  subplot(211)
+  stem(delta_t_log)
+  title('delta t');
+  subplot(212)
+  plot(timing_est_log,';timing est;');
+  hold on; plot(sample_point_log,';sample point;'); hold off;
+
+  figure(5); clf;
+  plot(foff_est_hz_log)
+  mx = max(abs(foff_est_hz_log))+1;
+  axis([1 max(Nframes,2) -mx mx]);
+  title('Fine Freq');
+  ylabel('Hz')
+
+  figure(6); clf;
+  stem(Nerrs_log);
+  title('Errors/modem frame')
+  if length(Nerrs_log) > 1
+      axis([1 length(Nerrs_log) 0 Nbitsperframe*rate/2]);
+  endif
+
+  figure(7); clf;
+  plot(snr_log);
+  title('SNR estimates');
+
+  figure(8); clf; plot_specgram(rx, 8000, 500, 2500);
+
+  % optional pass criteria for ctests
+  if pass_ber > 0
+    if packet_count && (ber < pass_ber) printf("Pass!\n"); else printf("Fail!\n"); end;
+  end
+  if pass_packet_count > 0
+    if packet_count >= pass_packet_count printf("Pass!\n"); else printf("Fail!\n"); end;
+  end
+endfunction