amodem
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Published
20 hours ago •
romanz
romanz
Decoding failed
Hi! I am testing this on some of my systems and can't get a transfer to work:
Sender (using aplay because amodem picks the wrong interface):
$ echo 123 | amodem send -vvvv -o - | aplay
2021-08-03 12:49:32,213 INFO Audio OFDM MODEM v1.15.3: 1.0 kb/s (2-QAM x 1 carriers) Fs=8.0 kHz __main__.py:230
Playing raw data 'stdin' : Unsigned 8 bit, Rate 8000 Hz, Mono
2021-08-03 12:49:32,221 INFO Sending 1.050 seconds of training audio main.py:23
2021-08-03 12:49:32,221 INFO Starting modulation main.py:28
2021-08-03 12:49:32,226 INFO Sent 0.004 kB @ 0.113 seconds main.py:32
2021-08-03 12:49:32,226 DEBUG Finished I/O __main__.py:261
$
Receiver:
$ amodem recv -vv
2021-08-03 12:49:31,789 INFO Audio OFDM MODEM v1.15.3: 1.0 kb/s (2-QAM x 1 carriers) Fs=8.0 kHz __main__.py:230
2021-08-03 12:49:31,790 INFO b'PortAudio V19.6.0-devel, revision 396fe4b6699ae929d3a685b3ef8a7e97396139a4' loaded audio.py:21
ALSA lib pcm_dsnoop.c:642:(snd_pcm_dsnoop_open) unable to open slave
ALSA lib pcm_dmix.c:1090:(snd_pcm_dmix_open) unable to open slave
ALSA lib pcm.c:2660:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.rear
ALSA lib pcm.c:2660:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.center_lfe
ALSA lib pcm.c:2660:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.side
ALSA lib pcm_oss.c:377:(_snd_pcm_oss_open) Unknown field port
ALSA lib pcm_oss.c:377:(_snd_pcm_oss_open) Unknown field port
ALSA lib pcm_usb_stream.c:486:(_snd_pcm_usb_stream_open) Invalid type for card
ALSA lib pcm_usb_stream.c:486:(_snd_pcm_usb_stream_open) Invalid type for card
ALSA lib pcm_dmix.c:1090:(snd_pcm_dmix_open) unable to open slave
2021-08-03 12:49:31,878 DEBUG AsyncReader thread started async_reader.py:26
2021-08-03 12:49:31,878 DEBUG Skipping 0.100 seconds main.py:46
2021-08-03 12:49:32,572 INFO Waiting for carrier tone: 2.0 kHz main.py:53
2021-08-03 12:49:36,086 INFO Carrier detected at ~3634.0 ms @ 2.0 kHz detect.py:60
2021-08-03 12:49:36,087 DEBUG Buffered 1000 ms of audio detect.py:63
2021-08-03 12:49:36,088 INFO Carrier coherence: 71.645% detect.py:94
2021-08-03 12:49:36,088 DEBUG Carrier starts at 3714.625 ms detect.py:73
2021-08-03 12:49:36,089 INFO Carrier symbols amplitude : 0.916 detect.py:105
2021-08-03 12:49:36,090 INFO Frequency error: 1.633 ppm detect.py:115
2021-08-03 12:49:36,090 DEBUG Frequency correction: -1.633 ppm main.py:57
2021-08-03 12:49:36,090 DEBUG Gain correction: 1.092 main.py:60
2021-08-03 12:49:36,090 DEBUG Receiving recv.py:161
2021-08-03 12:49:36,106 ERROR Decoding failed main.py:67
Traceback (most recent call last):
File "/home/david/.local/lib/python3.8/site-packages/amodem/main.py", line 64, in recv
receiver.run(sampler, gain=1.0/amplitude, output=dst)
File "/home/david/.local/lib/python3.8/site-packages/amodem/recv.py", line 163, in run
self._prefix(symbols, gain=gain)
File "/home/david/.local/lib/python3.8/site-packages/amodem/recv.py", line 49, in _prefix
raise ValueError(msg)
ValueError: Incorrect prefix: 50 errors
2021-08-03 12:49:36,175 DEBUG AsyncReader thread stopped (read 67200 bytes) async_reader.py:31
2021-08-03 12:49:36,177 DEBUG Finished I/O __main__.py:261
However, calibration seems good?
2021-08-03 12:47:20,394 INFO 2000 Hz: good signal total=0.9294, rms=0.9291, coherency=0.9996, peak=0.9813 calib.py:141
2021-08-03 12:47:20,594 INFO 2000 Hz: good signal total=0.9205, rms=0.9201, coherency=0.9996, peak=0.9687 calib.py:141
2021-08-03 12:47:20,809 INFO 2000 Hz: good signal total=0.9119, rms=0.9116, coherency=0.9996, peak=0.9649 calib.py:141
2021-08-03 12:47:20,985 INFO 2000 Hz: good signal total=0.9052, rms=0.9048, coherency=0.9996, peak=0.9596 calib.py:141
2021-08-03 12:47:21,214 INFO 2000 Hz: good signal total=0.9077, rms=0.9073, coherency=0.9996, peak=0.9631 calib.py:141
2021-08-03 12:47:21,413 INFO 2000 Hz: good signal total=0.9063, rms=0.9060, coherency=0.9996, peak=0.9611 calib.py:141
2021-08-03 12:47:21,613 INFO 2000 Hz: good signal total=0.9061, rms=0.9057, coherency=0.9996, peak=0.9582 calib.py:141
2021-08-03 12:47:21,814 INFO 2000 Hz: good signal total=0.9074, rms=0.9070, coherency=0.9996, peak=0.9605 calib.py:141
2021-08-03 12:47:21,986 INFO 2000 Hz: good signal total=0.9075, rms=0.9071, coherency=0.9996, peak=0.9640 calib.py:141
2021-08-03 12:47:22,171 INFO 2000 Hz: good signal total=0.9067, rms=0.9063, coherency=0.9996, peak=0.9563 calib.py:141
2021-08-03 12:47:22,371 INFO 2000 Hz: good signal total=0.9077, rms=0.9073, coherency=0.9996, peak=0.9636 calib.py:141
2021-08-03 12:47:22,598 INFO 2000 Hz: good signal total=0.9078, rms=0.9074, coherency=0.9996, peak=0.9638 calib.py:141
2021-08-03 12:47:22,772 INFO 2000 Hz: good signal total=0.9061, rms=0.9057, coherency=0.9996, peak=0.9608 calib.py:141
2021-08-03 12:47:22,971 INFO 2000 Hz: good signal total=0.9073, rms=0.9069, coherency=0.9996, peak=0.9599 calib.py:141
2021-08-03 12:47:23,202 INFO 2000 Hz: good signal total=0.9064, rms=0.9060, coherency=0.9996, peak=0.9592 calib.py:141
2021-08-03 12:47:23,397 INFO 2000 Hz: good signal total=0.9062, rms=0.9058, coherency=0.9996, peak=0.9606 calib.py:141
2021-08-03 12:47:23,598 INFO 2000 Hz: good signal total=0.9085, rms=0.9081, coherency=0.9996, peak=0.9623 calib.py:141
2021-08-03 12:47:23,798 INFO 2000 Hz: good signal total=0.9069, rms=0.9065, coherency=0.9996, peak=0.9608 calib.py:141
2021-08-03 12:47:23,998 INFO 2000 Hz: good signal total=0.9053, rms=0.9049, coherency=0.9996, peak=0.9564 calib.py:141
2021-08-03 12:47:24,202 INFO 2000 Hz: good signal total=0.9074, rms=0.9070, coherency=0.9996, peak=0.9604 calib.py:141
2021-08-03 12:47:24,402 INFO 2000 Hz: good signal total=0.9041, rms=0.9037, coherency=0.9996, peak=0.9534 calib.py:141
2021-08-03 12:47:24,602 INFO 2000 Hz: good signal total=0.9050, rms=0.9047, coherency=0.9996, peak=0.9611 calib.py:141
2021-08-03 12:47:24,802 INFO 2000 Hz: good signal total=0.9068, rms=0.9064, coherency=0.9996, peak=0.9576
Can you advise? Thanks
For what it's worth, I'm having similar problems. I'm running the sender and receiver on the same computer. I've also tried against the Android app. I believe the only success I've had is from the computer to the app. Here are my logs for a local calibration and test, and the matplotlib graphs (of a subsequent test).
amodem_rx.log
amodem_rx_cal.log
amodem_tx.log
amodem_tx_cal.log
Ok, so I DID just manage to get a message from the phone to the computer. I turned down the volume on my phone and the mic on the computer and put the speaker within an inch of the microphone. Looks like it's just not very tolerant of noise? Is there a way to improve that? Further reduce the bitrate or something?
Ah - one problem is that aplay and arecord don't play at the correct samplerates, I think. A little more investigation to follow.
I dunno. :/ In increments, I've turned the symbol length up by a factor of 20, decreased the frequency to 6e2, increased the sample rate to 32e3, left Npoints at 2, messed a lot with the volumes - nothing seems to work.