From 074404b522ec0ae053508cb2d7ad10f48e79e4a6 Mon Sep 17 00:00:00 2001 From: drowe67 Date: Fri, 20 Apr 2018 00:23:51 +0000 Subject: [PATCH] output formatting changes and more examples git-svn-id: https://svn.code.sf.net/p/freetel/code@3512 01035d8c-6547-0410-b346-abe4f91aad63 --- codec2-dev/README_ofdm.txt | 23 +++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-) diff --git a/codec2-dev/README_ofdm.txt b/codec2-dev/README_ofdm.txt index 7564f213..0524eb39 100644 --- a/codec2-dev/README_ofdm.txt +++ b/codec2-dev/README_ofdm.txt @@ -77,18 +77,32 @@ Built as part of codec2-dev, see README for build instructions. build_linux/src$ ./ofdm_demod ../../octave/ofdm_test.raw /dev/null -v -t --ldpc --interleave 4 -6. Run C mod/demod with LDPC and 2 frames interleaving: +6. Run C mod/demod with LDPC and 2 frames interleaving: - build_linux/src$ ./ofdm_mod /dev/zero - --ldpc -t 2 --interleave 2 | ./ofdm_demod - /dev/null -t --ldpc -v --interleave 2 + build_linux/src$ ./ofdm_mod /dev/zero - --ldpc -t 2 --interleave 2 | ./ofdm_demod - /dev/null -t --ldpc -v --interleave 2 -7. Pass Codec 2 700C through modem: +7. Pass Codec 2 700C compressed speech through OFDM modem: - build_linux/src$ ./c2enc 700C ../../raw/ve9qrp_10s.raw - --bitperchar | ./ofdm_mod - - --ldpc --interleave 2 | ./ofdm_demod - - --ldpc --interleave 2 | ./c2dec 700C - - --bitperchar | play -t raw -r 8000 -s -2 - + build_linux/src$ ./c2enc 700C ../../raw/ve9qrp_10s.raw - --bitperchar | ./ofdm_mod - - --ldpc --interleave 2 | ./ofdm_demod - - --ldpc --interleave 2 | ./c2dec 700C - - --bitperchar | play -t raw -r 8000 -s -2 - + +8. Listen to signal through simulated fading channel in C: + + build_linux/src$ ./c2enc 700C ../../raw/ve9qrp_10s.raw - --bitperchar | ./ofdm_mod - - --ldpc --interleave 4 | ./cohpsk_ch - - -20 -Fs 8000 --slow -f -5 | aplay -f S16 + +9. Run test frames through simulated chanel in C: + + build_linux/src$ ./ofdm_mod /dev/zero - --interleave 16 --ldpc -t 60 | ./cohpsk_ch - - -19 --Fs 8000 | ./ofdm_demod - /dev/null -t --interleave 16 + +10. Run codec voice through simulated fast fading channel, just where it starts to fall over: + + build_linux/src$ ./c2enc 700C ../../raw/ve9qrp.raw - --bitperchar | ./ofdm_mod - - --ldpc --interleave 16 | ./cohpsk_ch - - -22 --Fs 8000 -f -10 --fast | ./ofdm_demod - - --ldpc -v --interleave 16 | ./c2dec 700C - - --bitperchar | aplay -f S16 Acceptance Tests ---------------- +Run these if you modify anything. + The rate 1/2 LDPC code can correct up to about 10% raw BER, so a good test is to run the modem at Eb/No operating points that produce just less that BER=0.1 @@ -121,6 +135,7 @@ ofdm_demod - OFDM demodulator command line program, supports uncoded LDPC decoder ofdm_put_test_bits - measure BER in OFDM test frames unittest/tofdm - Run C port of modem to compare with octave version (see octave/tofdm) +cohpsk_ch - From COHPSK modem development, useful C channel simulator Octave Scripts -------------- -- 2.25.1