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libs/libcodec2/octave/fdmdv_mod.m

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+% fdmdv_mod.m
+%
+% Modulator function for FDMDV modem, uses test frames as input and
+% outputs a raw file of 16 bit shorts at a sample rate of 8 kHz.
+%
+% Copyright David Rowe 2012
+% This program is distributed under the terms of the GNU General Public License 
+% Version 2
+%
+
+function tx_fdm = fdmdv_mod(rawfilename, nbits)
+
+  fdmdv; % include modem code
+
+  frames = floor(nbits/(Nc*Nb))
+  tx_fdm = [];
+  gain = 1000; % Scale up to 16 bit shorts
+  prev_tx_symbols = ones(Nc+1,1);
+
+  for i=1:frames
+    tx_bits = get_test_bits(Nc*Nb);
+    tx_symbols = bits_to_qpsk(prev_tx_symbols, tx_bits,'dqpsk');
+    prev_tx_symbols = tx_symbols;
+    tx_baseband = tx_filter(tx_symbols);
+    tx_fdm = [tx_fdm real(fdm_upconvert(tx_baseband))];
+  end
+
+  tx_fdm *= gain;
+  fout = fopen(rawfilename,"wb");
+  fwrite(fout, tx_fdm, "short");
+  fclose(fout);
+endfunction