% test_ldpc_fsk_lib\r
% David Rowe 16 April 2016\r
%\r
-% Some tests for ldpc_fsk_lib, and C versions ldpc_enc and ldpc_dec\r
+% A series of tests for ldpc_fsk_lib, and C versions ldpc_enc and ldpc_dec.\r
+% Gradually builds up complete C command line for SSTV balloon system,\r
+% using Octave versions of LDPC and FSK modem as reference points.\r
\r
1;\r
\r
end\r
\r
\r
-% plots a BER curve for the decoder. Takes a while to run, uses parallel cores\r
+% plots a BER curve for the LDPC decoder. Takes a while to run, uses parallel cores\r
\r
function plot_curve\r
num_cores = 4; % set this to the number of cores you have\r
%iq(2:2:2*l) = 127 + im*(127/mx); \r
iq(1:2:2*l) = 127 + 32*re; \r
iq(2:2:2*l) = 127 + 32*im; \r
- figure(3); clf; plot(iq);\r
+ figure(3); clf; plot(iq); title('simulated IQ signal from RTL SDR');\r
fs = fopen(filename,"wb");\r
fwrite(fs,iq,"uchar");\r
fclose(fs);\r
\r
\r
% Using simulated SSTV packet, generate complex fsk mod signals, 8-bit\r
-% unsigned IQ for feeding into demod chain\r
+% unsigned IQ for feeding into C demod chain. Can also be used to\r
+% generate BER curves. Found bugs in UW size and our use of csdr\r
+% re-sampler using this function, and by gradually and carefully\r
+% building up the C command line.\r
+\r
#{\r
todo: [X] uncoded BER\r
[X] octave fsk demod\r
[X] use C demod\r
- [ ] compare uncoded BER to unsigned 8 bit IQ to regular 16-bit\r
- [ ] generate complex rx signal with noise\r
- [ ] used cmd line utils to drive demod\r
- [ ] test with resampler\r
- [ ] measure effect on PER with coding\r
+ [X] compare uncoded BER to unsigned 8 bit IQ to regular 16-bit\r
+ [X] generate complex rx signal with noise\r
+ [X] used cmd line utils to drive demod\r
+ [X] test with resampler\r
+ [X] measure effect on PER with coding\r
#}\r
\r
function [n_uncoded_errs n_uncoded_bits] = run_sstv_sim(sim_in, EbNodB)\r
% note fixed frame of bits used for BER testing\r
\r
tx_codeword = gen_sstv_frame;\r
- length(tx_codeword)\r
+\r
% init FSK modem\r
\r
fsk_horus_as_a_lib = 1;\r
states.dA(1:states.M) = 1;\r
states.tx_real = 0; % Octave fsk_mod generates complex valued output\r
\r
- % Set up simulated tx tones to sit in teh middle of cdsr passband\r
+ % Set up simulated tx tones to sit in the middle of cdsr passband\r
\r
filt_low_norm = 0.1; filt_high_norm = 0.4;\r
fc = states.Fs*(filt_low_norm + filt_high_norm)/2;\r
%fc = 1800;\r
- f1 = fc - states.Rs/2\r
- f2 = fc + states.Rs/2\r
+ f1 = fc - states.Rs/2;\r
+ f2 = fc + states.Rs/2;\r
states.ftx = [f1 f2];\r
\r
% set up AWGN channel \r
noise_real = sqrt(variance)*randn(length(tx),1);\r
noise_complex = sqrt(variance/2)*(randn(length(tx),1) + j*randn(length(tx),1));\r
\r
- % demodulate\r
+ % demodulate -----------------------------------------------------\r
\r
if demod_type == 1\r
\r
end\r
\r
if demod_type == 3\r
- % C demod driven by command line kung fu\r
+ % C demod driven by csdr command line kung fu\r
\r
assert(states.tx_real == 0, "need complex signal for this test");\r
rx = tx + noise_complex;\r
rx = tx + noise_complex;\r
SNRdB = 10*log10(var(tx)/var(noise_real));\r
\r
- % interpolate by factor or 2, then use straight line interpolation\r
-\r
printf("resampling ...\n");\r
rx_resample_fract = fractional_resample(rx, 1.08331);\r
%rx_resample_fract = fractional_resample(rx_resample_fract, 1/1.08331);\r
printf("run C cmd line chain ...\n");\r
% system("cat fsk_demod_resample.iq | csdr convert_u8_f | csdr bandpass_fir_fft_cc 0.1 0.4 0.05 | csdr realpart_cf | csdr convert_f_s16 | ../build_linux/src/fsk_demod 2X 8 9600 1200 - fsk_demod.bin");\r
system("cat fsk_demod_resample.iq | csdr convert_u8_f | csdr bandpass_fir_fft_cc 0.1 0.4 0.05 | csdr realpart_cf | csdr convert_f_s16 | ../unittest/tsrc - - 0.9230968 | ../build_linux/src/fsk_demod 2X 8 9600 1200 - fsk_demod.bin");\r
-% system("cat fsk_demod_resample.iq | csdr convert_u8_f | csdr bandpass_fir_fft_cc 0.1 0.4 0.05 | csdr fractional_decimator_ff 1.08331 | csdr realpart_cf | csdr convert_f_s16 | ../build_linux/src/fsk_demod 2X 8 9600 1200 - fsk_demod.bin");\r
+% system("cat fsk_demod_resample.iq | csdr convert_u8_f | csdr bandpass_fir_fft_cc 0.1 0.4 0.05 | csdr realpart_cf | csdr fractional_decimator_ff 1.08331 | csdr convert_f_s16 | ../build_linux/src/fsk_demod 2X 8 9600 1200 - fsk_demod.bin");\r
f = fopen("fsk_demod.bin","rb"); rx_bit_stream = fread(f, "uint8")'; fclose(f);\r
end\r
\r
- % state machine. Look for SSTV UW. When found count bit errors over one frame of bits\r
\r
- state = "wait for uw";\r
- start_uw_ind = 16*10+1; end_uw_ind = start_uw_ind + 5*10 - 1;\r
- uw_rs232 = tx_codeword(start_uw_ind:end_uw_ind); luw = length(uw_rs232);\r
- start_frame_ind = end_uw_ind + 1;\r
- nbits = length(rx_bit_stream);\r
- uw_thresh = 5;\r
- n_uncoded_errs = 0;\r
- n_uncoded_bits = 0;\r
- n_packets_rx = 0;\r
- last_i = 0;\r
+ if demod_type == 5\r
+\r
+ % C demod with resampler and use C code to measure PER, in this\r
+ % test we don't need to run state machine below as C code gives us\r
+ % the ouputs we need\r
\r
- % might as well include RS232 framing bits in uncoded error count\r
+ assert(states.tx_real == 0, "need complex signal for this test");\r
+ rx = tx + noise_complex;\r
+ SNRdB = 10*log10(var(tx)/var(noise_real));\r
+ \r
+ printf("resampling ...\n");\r
+ rx_resample_fract = fractional_resample(rx, 1.08331);\r
+ save_rtlsdr("fsk_demod_resample.iq", rx_resample_fract);\r
\r
- nbits_frame = code_param.data_bits_per_frame*10/8; \r
+ printf("run C cmd line chain - uncoded PER\n");\r
+ system("cat fsk_demod_resample.iq | csdr convert_u8_f | csdr bandpass_fir_fft_cc 0.1 0.4 0.05 | csdr realpart_cf | csdr convert_f_s16 | ../unittest/tsrc - - 0.9230968 | ../build_linux/src/fsk_demod 2X 8 9600 1200 - - | ../src/drs232 - /dev/null -v");\r
\r
- uw_errs = zeros(1, nbits);\r
- for i=luw:nbits\r
- uw_errs(i) = sum(xor(rx_bit_stream(i-luw+1:i), uw_rs232));\r
+ printf("run C cmd line chain - LDPC coded PER\n");\r
+ system("cat fsk_demod_resample.iq | csdr convert_u8_f | csdr bandpass_fir_fft_cc 0.1 0.4 0.05 | csdr realpart_cf | csdr convert_f_s16 | ../unittest/tsrc - - 0.9230968 | ../build_linux/src/fsk_demod 2XS 8 9600 1200 - - | ../src/drs232_ldpc - /dev/null -v");\r
end\r
\r
- for i=luw:nbits\r
- next_state = state;\r
- if strcmp(state, 'wait for uw')\r
- if uw_errs(i) <= uw_thresh\r
- next_state = 'count errors';\r
- tx_frame_ind = start_frame_ind;\r
- rx_frame_ind = i + 1;\r
- n_uncoded_errs_this_frame = 0;\r
- %printf("%d %s %s\n", i, state, next_state);\r
- if last_i\r
- printf("i: %d i-last_i: %d ", i, i-last_i);\r
+ if demod_type != 5\r
+ % state machine. Look for SSTV UW. When found count bit errors over one frame of bits\r
+\r
+ state = "wait for uw";\r
+ start_uw_ind = 16*10+1; end_uw_ind = start_uw_ind + 5*10 - 1;\r
+ uw_rs232 = tx_codeword(start_uw_ind:end_uw_ind); luw = length(uw_rs232);\r
+ start_frame_ind = end_uw_ind + 1;\r
+ nbits = length(rx_bit_stream);\r
+ uw_thresh = 5;\r
+ n_uncoded_errs = 0;\r
+ n_uncoded_bits = 0;\r
+ n_packets_rx = 0;\r
+ last_i = 0;\r
+\r
+ % might as well include RS232 framing bits in uncoded error count\r
+\r
+ nbits_frame = code_param.data_bits_per_frame*10/8; \r
+\r
+ uw_errs = zeros(1, nbits);\r
+ for i=luw:nbits\r
+ uw_errs(i) = sum(xor(rx_bit_stream(i-luw+1:i), uw_rs232));\r
+ end\r
+\r
+ for i=luw:nbits\r
+ next_state = state;\r
+ if strcmp(state, 'wait for uw')\r
+ if uw_errs(i) <= uw_thresh\r
+ next_state = 'count errors';\r
+ tx_frame_ind = start_frame_ind;\r
+ rx_frame_ind = i + 1;\r
+ n_uncoded_errs_this_frame = 0;\r
+ %printf("%d %s %s\n", i, state, next_state);\r
+ if last_i\r
+ printf("i: %d i-last_i: %d ", i, i-last_i);\r
+ end\r
end\r
end\r
- end\r
- if strcmp(state, 'count errors')\r
- n_uncoded_errs_this_frame += xor(rx_bit_stream(i), tx_codeword(tx_frame_ind));\r
- n_uncoded_bits++;\r
- tx_frame_ind++;\r
- if tx_frame_ind == (start_frame_ind+nbits_frame)\r
- n_uncoded_errs += n_uncoded_errs_this_frame;\r
- printf("n_uncoded_errs_this_frame: %d\n", n_uncoded_errs_this_frame);\r
- frame_rx232_rx = rx_bit_stream(rx_frame_ind:rx_frame_ind+nbits_frame-1);\r
- %tx_codeword(start_frame_ind+1:start_frame_ind+10)\r
- %frame_rx232_rx(1:10)\r
- sstv_checksum(frame_rx232_rx);\r
- last_i = i;\r
- n_packets_rx++;\r
- next_state = 'wait for uw';\r
+ if strcmp(state, 'count errors')\r
+ n_uncoded_errs_this_frame += xor(rx_bit_stream(i), tx_codeword(tx_frame_ind));\r
+ n_uncoded_bits++;\r
+ tx_frame_ind++;\r
+ if tx_frame_ind == (start_frame_ind+nbits_frame)\r
+ n_uncoded_errs += n_uncoded_errs_this_frame;\r
+ printf("n_uncoded_errs_this_frame: %d\n", n_uncoded_errs_this_frame);\r
+ frame_rx232_rx = rx_bit_stream(rx_frame_ind:rx_frame_ind+nbits_frame-1);\r
+ %tx_codeword(start_frame_ind+1:start_frame_ind+10)\r
+ %frame_rx232_rx(1:10)\r
+ sstv_checksum(frame_rx232_rx);\r
+ last_i = i;\r
+ n_packets_rx++;\r
+ next_state = 'wait for uw';\r
+ end\r
end\r
+ state = next_state;\r
end\r
- state = next_state;\r
- end\r
\r
- uncoded_ber = n_uncoded_errs/n_uncoded_bits;\r
- printf("EbNodB: %4.1f SNRdB: %4.1f pkts: %d bits: %d errs: %d BER: %4.3f\n", \r
- EbNodB, SNRdB, n_packets_rx, n_uncoded_bits, n_uncoded_errs, uncoded_ber); \r
+ uncoded_ber = n_uncoded_errs/n_uncoded_bits;\r
+ printf("EbNodB: %4.1f SNRdB: %4.1f pkts: %d bits: %d errs: %d BER: %4.3f\n", \r
+ EbNodB, SNRdB, n_packets_rx, n_uncoded_bits, n_uncoded_errs, uncoded_ber); \r
\r
- figure(2);\r
- plot(uw_errs);\r
+ figure(2);\r
+ plot(uw_errs);\r
+ title('Unique Word Hamming Distance')\r
+ end\r
\r
endfunction\r
\r
\r
% ------------------ select which demo/test to run here ---------------\r
\r
-demo = 10;\r
+demo = 11;\r
\r
if demo == 1\r
printf("simple_ut....\n");\r
test_c_decoder;\r
end\r
\r
+% generates simulated demod soft decision symbols to drive C ldpc decoder with\r
+\r
if demo == 8\r
frames = 100;\r
EsNodB = 3;\r
end\r
\r
\r
+% Plots uncoded BER curves for two different SSTV simulations. Used\r
+% to compare results with different processing steps as we build up C\r
+% command line. BER curves are powerful ways to confirm system is\r
+% operating as expected, several bugs were found using this system.\r
+\r
if demo == 10\r
- sim_in.frames = 100;\r
- EbNodBvec = 7;\r
+ sim_in.frames = 10;\r
+ EbNodBvec = 7:10;\r
\r
- sim_in.demod_type = 4;\r
- ber_octave = [];\r
+ sim_in.demod_type = 3;\r
+ ber_test1 = [];\r
for i = 1:length(EbNodBvec)\r
[n_uncoded_errs n_uncoded_bits] = run_sstv_sim(sim_in, EbNodBvec(i));\r
- ber_octave(i) = n_uncoded_errs/n_uncoded_bits;\r
+ ber_test1(i) = n_uncoded_errs/n_uncoded_bits;\r
end\r
- #{\r
+ \r
sim_in.demod_type = 4;\r
ber_c = [];\r
for i = 1:length(EbNodBvec)\r
[n_uncoded_errs n_uncoded_bits] = run_sstv_sim(sim_in, EbNodBvec(i));\r
- ber_c(i) = n_uncoded_errs/n_uncoded_bits;\r
+ ber_test2(i) = n_uncoded_errs/n_uncoded_bits;\r
end\r
\r
figure(1);\r
clf;\r
- semilogy(EbNodBvec, ber_octave, '+-;first test;')\r
+ semilogy(EbNodBvec, ber_test1, '+-;first test;')\r
grid;\r
xlabel('Eb/No (dB)')\r
ylabel('BER')\r
\r
hold on;\r
- semilogy(EbNodBvec, ber_c, 'g+-;second test;')\r
+ semilogy(EbNodBvec, ber_test2, 'g+-;second test;')\r
legend("boxoff");\r
hold off;\r
- #}\r
+ \r
end\r
\r
+\r
+% Measure PER of complete coded and uncoded system\r
+\r
+if demo == 11\r
+ sim_in.frames = 100;\r
+ EbNodB = 13;\r
+ sim_in.demod_type = 5;\r
+ run_sstv_sim(sim_in, EbNodB);\r
+end\r
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