states.norm_rx_timing = 0;
states.ppm = 0;
states.prev_pkt = [];
-
+
% protocol specific states
states.rtty = fsk_horus_init_rtty_uw(states);
states.binary = fsk_horus_init_binary_uw;
+
endfunction
function rtty = fsk_horus_init_rtty_uw(states)
% Generate unque word that correlates against the ASCII "$$$$$" that
% is at the start of each frame.
+ % $ -> 36 decimal -> 0 1 0 0 1 0 0 binary
dollar_bits = fliplr([0 1 0 0 1 0 0]);
mapped_db = 2*dollar_bits - 1;
nfield = rtty.nfield = 7; % length of ascii character field
rtty.uw = [mapped mapped mapped mapped mapped];
- rtty.uw_thresh = length(rtty.uw) - 8; % allow a few bit errors when looking for UW
+ rtty.uw_thresh = length(rtty.uw) - 2; % allow a few bit errors when looking for UW
rtty.max_packet_len = 1000;
endfunction
mapped_db = 2*dollar_bits - 1;
binary.uw = [mapped_db mapped_db];
- binary.uw_thresh = length(binary.uw) - 2; % no bit errors when looking for UW
+ binary.uw_thresh = length(binary.uw)-2; % no bit errors when looking for UW
binary.max_packet_len = 360-16;
endfunction
Ndft = states.Ndft;
Fs = states.Fs;
- % This assumption is OK for balloon telemtry but may not be true in
+ % This assumption is OK for balloon telemetry but may not be true in
% general
min_tone_spacing = 200;
% set some limits to search range, which will mean some manual re-tuning
- fmin = 800; fmax = 2000;
+ fmin = 800; fmax = 2500;
st = floor(fmin*Ndft/Fs);
en = floor(fmax*Ndft/Fs);
f = []; a = [];
Sf = states.Sf;
- figure(8)
- clf
- plot(Sf(1:Ndft/2));
+ %figure(8)
+ %clf
+ %plot(Sf(1:Ndft/2));
% Search for each tone --------------------------------------------------------
% We have sampled the integrator output at Fs=P samples/symbol, so
% lets do a single point DFT at w = 2*pi*f/Fs = 2*pi*Rs/(P*Rs)
%
- % Note timing non-lineariry derivedby experiment. Not quite sure what I'm doing here.....
+ % Note timing non-lineariry derived by experiment. Not quite sure what I'm doing here.....
% but it gives 0dB impl loss for 2FSK Eb/No=9dB, testmode 1:
% Fs: 8000 Rs: 50 Ts: 160 nsym: 50
% frames: 200 Tbits: 9700 Terrs: 93 BER 0.010
% UW found Sometimes there may be several matches, returns the
% position of the best match to UW.
-function [uw_start best_corr] = find_uw(states, start_bit, rx_bits)
+function [uw_start best_corr corr] = find_uw(states, start_bit, rx_bits)
uw = states.uw;
mapped_rx_bits = 2*rx_bits - 1;
% first first UW in buffer that exceeds threshold
for i=start_bit:length(rx_bits) - length(uw)
- corr = mapped_rx_bits(i:i+length(uw)-1) * uw';
- if (found_uw == 0) && (corr >= states.uw_thresh)
+ corr(i) = mapped_rx_bits(i:i+length(uw)-1) * uw';
+ if (found_uw == 0) && (corr(i) >= states.uw_thresh)
uw_start = i;
best_corr = corr;
found_uw = 1;
nfield = states.rtty.nfield;
npad = states.rtty.npad;
- uw_loc = find_uw(states.rtty, bit, rx_bits_log);
-
+ uw_loc = find_uw(states.rtty, bit, rx_bits_log, states.verbose);
+
while (uw_loc != -1)
if (uw_loc + states.rtty.max_packet_len) < nbits
% look for next packet
bit = uw_loc + length(states.rtty.uw);
- uw_loc = find_uw(states.rtty, bit, rx_bits_log);
+ uw_loc = find_uw(states.rtty, bit, rx_bits_log, states.verbose);
endwhile
endfunction
% compile with:
% codec2-dev/src$ gcc horus_l2.c -o horus_l2 -Wall -DDEC_RX_BITS -DHORUS_L2_RX
-function extract_and_decode_binary_packets(states, rx_bits_log)
+function corr_log = extract_and_decode_binary_packets(states, rx_bits_log)
+ corr_log = [];
% use UWs to delimit start and end of data packets
bit = 1;
nbits = length(rx_bits_log);
- [uw_loc best_corr] = find_uw(states.binary, bit, rx_bits_log);
+ [uw_loc best_corr corr] = find_uw(states.binary, bit, rx_bits_log, states.verbose);
+ corr_log = [corr_log corr];
while (uw_loc != -1)
end
bit = uw_loc + length(states.binary.uw);
- [uw_loc best_corr] = find_uw(states.binary, bit, rx_bits_log);
+ [uw_loc best_corr corr] = find_uw(states.binary, bit, rx_bits_log, states.verbose);
+ corr_log = [corr_log corr];
endwhile
endfunction
% simulation of tx and rx side, add noise, channel impairments ----------------------
function run_sim(test_frame_mode)
- test_frame_mode=5;
- frames = 100;
- EbNodB = 6;
+ test_frame_mode = 5;
+ frames = 10;
+ EbNodB = 60;
timing_offset = 0.0; % see resample() for clock offset below
fading = 0; % modulates tx power at 2Hz with 20dB fade depth,
% to simulate balloon rotating at end of mission
tx_bits(1:2:length(tx_bits)) = 1;
else
% repeat each possible 4fsk symbol
- %pattern = [0 0 0 1 1 0 1 1];
- pattern = [0 0 0 1 0 0 0 1];
+ pattern = [0 0 0 1 1 0 1 1];
+ %pattern = [0 0 0 1 1 1 1 0];
nrepeats = states.nbit*(frames+1)/length(pattern);
tx_bits = [];
for b=1:nrepeats
%rx(find (rx < -1)) = -1;
% dump simulated rx file
- ftx=fopen("fsk_horus_100bd_binary.raw","wb"); rxg = rx*1000; fwrite(ftx, rxg, "short"); fclose(ftx);
+ ftx=fopen("fsk_horus.raw","wb"); rxg = rx*1000; fwrite(ftx, rxg, "short"); fclose(ftx);
timing_offset_samples = round(timing_offset*states.Ts);
st = 1 + timing_offset_samples;
end
end
+
if test_frame_mode == 1
printf("frames: %d EbNo: %3.2f Tbits: %d Terrs: %d BER %4.3f\n", frames, EbNodB, states.Tbits,states. Terrs, states.Terrs/states.Tbits);
end
axis([-m m -m m])
title('fine timing metric')
- figure(7)
- clf
- subplot(211)
- X = abs(fft(timing_nl_log));
- plot(X(1:length(X)/2))
- subplot(212)
- plot(abs(timing_nl_log(1:100)))
-
figure(3)
clf
subplot(211)
plot(EbNodB_log);
title('Eb/No estimate')
-endfunction
+ figure(7)
+ clf
+ subplot(211)
+ X = abs(fft(timing_nl_log));
+ plot(X(1:length(X)/2))
+ subplot(212)
+ plot(abs(timing_nl_log(1:100)))
+
+ endfunction
% demodulate a file of 8kHz 16bit short samples --------------------------------
if test_frame_mode == 4
% horus rtty config ---------------------
- states = fsk_horus_init(8000, 50, 4);
+ states = fsk_horus_init(8000, 100, 2);
uwstates = fsk_horus_init_rtty_uw(states);
end
if test_frame_mode == 5
% horus binary config ---------------------
- states = fsk_horus_init(8000, 100);
+ states = fsk_horus_init(8000, 50, 4);
uwstates = fsk_horus_init_binary_uw;
end
- states.verbose = 0x1;
+ states.verbose = 0x1 + 0x8;
N = states.N;
P = states.P;
% demodulate to stream of bits
states = est_freq(states, sf, states.M);
+ %states.f = [1450 1590 1710 1850];
[rx_bits states] = fsk_horus_demod(states, sf);
rx_bits_buf(1:nbit) = rx_bits_buf(nbit+1:2*nbit);
states.verbose = 0;
end
end
- else finished = 1;
+ else
+ finished = 1;
end
end
fclose(fin);
if (test_frame_mode == 4) || (test_frame_mode == 5)
extract_and_print_rtty_packets(states, rx_bits_log, rx_bits_sd_log)
- extract_and_decode_binary_packets(states, rx_bits_log);
+ corr_log = extract_and_decode_binary_packets(states, rx_bits_log);
+
+ figure(8);
+ clf
+ plot(corr_log);
+ hold on;
+ plot([1 length(corr_log)],[states.binary.uw_thresh states.binary.uw_thresh],'g');
+ hold off;
+ title('UW correlation');
end
+
endfunction
% run test functions from here during development
if exist("fsk_horus_as_a_lib") == 0
- run_sim(5);
+ %run_sim(5);
+ rx_bits = demod_file("~/Desktop/4FSK_Scram_Interleaved.wav",5);
+ %rx_bits = demod_file("fsk_horus.raw",5);
%rx_bits = demod_file("~/Desktop/4FSK_Binary_NoLock.wav",4);
- %rx_bits = demod_file("fsk_horus_100bd_binary.raw",5);
%rx_bits = demod_file("~/Desktop/phorus_binary_ascii.wav",4);
%rx_bits = demod_file("~/Desktop/binary/horus_160102_binary_rtty_2.wav",4);
%rx_bits = demod_file("~/Desktop/horus_160102_vk5ei_capture2.wav",4);
projects / freetel-svn-tracking.git / commitdiff