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no output #62

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project-owner opened this issue Sep 30, 2018 · 8 comments

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commented Sep 30, 2018

No output from redsea, I've tried about dozen different stations here in San Francisco Bay Area but no avail.
Here is the syntax which I tried:
rtl_fm -M fm -l 0 -A std -p 0 -s 171k -g 40 -F 9 -f 96.5M | redsea -e | aplay -r 171000 -f S16_LE
rtl_fm -M fm -l 0 -A std -p 0 -s 171k -g 40 -F 9 -f 96.5M | redsea -e -u | aplay -r 171000 -f S16_LE
I can hear audio but no output from redsea in terminal. I also tried weird syntax suggested here:
#59
but still no output. Just wondering if I'm doing something wrong.
Thanks in advance!

@windytan

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commented Oct 1, 2018

Thanks for the report!

It doesn't look like you're doing anything wrong. A couple of questions:

  • Are you able to get output from redsea without the -e option (and the pipe to aplay)?
  • Is this a Linux system?
@project-owner

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commented Oct 1, 2018

No output without aplay either:
rtl_fm -M fm -l 0 -A std -p 0 -s 171k -g 40 -F 9 -f 96.5M | redsea
This is Raspbian Stretch Desktop running on Raspberry Pi 3+. I'm using the latest version of redsea.
I tried the same stations/frequencies on Windows machine with SDR# and I saw the RDS messages there
for the same stations.
Thanks!

@project-owner

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commented Oct 1, 2018

Here is the output:
pi@raspberrypi:~ $ rtl_fm -M fm -l 0 -A std -p 0 -s 171k -g 40 -F 9 -f 97.3M | redsea
Found 1 device(s):
0: Realtek, RTL2838UHIDIR, SN: 00000001

Using device 0: Generic RTL2832U OEM
Detached kernel driver
Found Rafael Micro R820T tuner
Tuner gain set to 40.20 dB.
Tuned to 97642000 Hz.
oversampling input by: 8x.
Oversampling output by: 1x.
Buffer size: 5.99ms
Exact sample rate is: 1368000.013046 Hz
Create UDP thread
Created UDP thread
Main socket started! :-) Tuning enabled on UDP/6020
Sampling at 1368000 S/s.
Output at 171000 Hz.

@windytan

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commented Oct 2, 2018

You could try to change the gain (-g) to -g 20.

If that doesn't help, then I'd be interested in seeing a short (10-second) recording of that raw rtl_fm output.

@sm3ulc

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commented Oct 2, 2018

@project-owner

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commented Oct 2, 2018

I tried two different dongles with the same result:
https://www.amazon.com/NooElec-NESDR-SMArt-Bundle-R820T2-Based/dp/B01GDN1T4S
https://www.amazon.com/RTL-SDR-Blog-RTL2832U-Software-Telescopic/dp/B011HVUEME
I'm not sure how to calibrate the dongle. If I remove that parameter the result is the same.

-g 20 doesn't help.

I recorded three test files for different stations this way:
rtl_fm -M fm -l 0 -A std -s 171k -g 20 -F 9 -f 106.9M > test-106.9M.raw
They can be found here on github:
https://github.com/project-owner/Peppy.doc/blob/master/files/test-102.9M.raw
https://github.com/project-owner/Peppy.doc/blob/master/files/test-106.9M.raw
https://github.com/project-owner/Peppy.doc/blob/master/files/test-97.3M.raw

Please let me know if it works or if I need to use any other way to record those files.
Thanks!

@windytan

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commented Oct 2, 2018

Thanks for the files, they work well. I was able to decode them in redsea v0.16 and v0.17.1 on MacOS (I got callsigns KCBS, KLLC, KBLX). To me this looks very similar to the v0.15 bug you linked to earlier. Which version does redsea --version report?

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commented Oct 2, 2018

pi@raspberrypi:~ $ redsea --version
redsea 0.17.1 by OH2EIQ

Here is the output using that syntax (no RDS messages):
pi@raspberrypi:~ $ { rtl_fm -M fm -l 0 -A std -s 171k -g 20 -F 9 -f 106.9M | redsea -e 2>&1 1>&3 3>&- | jq -c . ; } 3>&1 1>&2 | aplay -r 171000 -f S16_LE
Found 1 device(s):
0: Realtek, RTL2838UHIDIR, SN: 00000001

Using device 0: Generic RTL2832U OEM
Detached kernel driver
Found Rafael Micro R820T tuner
Tuner gain set to 19.70 dB.
Tuned to 107242000 Hz.
oversampling input by: 8x.
Oversampling output by: 1x.
Buffer size: 5.99ms
Exact sample rate is: 1368000.013046 Hz
Create UDP thread
Created UDP thread
Main socket started! :-) Tuning enabled on UDP/6020
Sampling at 1368000 S/s.
Output at 171000 Hz.
Playing raw data 'stdin' : Signed 16 bit Little Endian, Rate 171000 Hz, Mono

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