31 Dec
2012
31 Dec
'12
6:29 a.m.
With rtl_fm, I get a tiny burst of audio about once a minute.
My dongle is a vendor ID 0x0bda, product ID0x2838 from
http://www.amazon.com/gp/browse.html?ie=UTF8&marketplaceID=ATVPDKIKX0DE…
I did:
rtl_fm -f 88500000 - | play -t raw -r 24k -e signed-integer -b 16 -c 1 -V1 -
I got:
Found 1 device(s):
0: Realtek, RTL2838UHIDIR, SN: 00000013
Using device 0: ezcap USB 2.0 DVB-T/DAB/FM dongle
Found Rafael Micro R820T tuner
-: (raw)
Encoding: Signed PCM
Channels: 1 @ 16-bit
Samplerate: 24000Hz
Replaygain: off
Duration: unknown
In:0.00% 00:00:00.00 [00:00:00.00] Out:0 [ | ] Clip:0
Oversampling input by: 42x.
Oversampling output by: 1x.
Buffer size: 8.13ms
Tuned to 88752000 Hz.
Sampling at 1008000 Hz.
Output at 24000 Hz.
Exact sample rate is: 1008000.009613 Hz
Tuner gain set to automatic.
In:0.00% 00:00:00.68 [00:00:00.00] Out:16.4k [ =====|===== ] Clip:0
^CSignal caught, exiting!
The dongle works if I boot into Windows, but in OpenBSD I can't get anything out of
it. I'm still trying to get dependencies for Gnuradio together. The only odd thing
is that being OpenBSD, there's no -lrt when I link. Those functions are built into
something else so I compile without the -lrt. There isn't an -lrt library.
I've tried writing little scripts to run it so I do it consistently. My wide FM one:
#!/bin/sh
rtl_fm -W -l 0 -f 88500000 - | play -t raw -r 32000 -e signed-integer -b 16 -c 1 -V4 -
Narrow:
#!/bin/sh
rtl_fm -N -l 0 -f 162550000 - | play -t raw -r 32k -e signed-integer -b 16 -c 1 -V4 -
I've played with various options. If I use -R it runs for a long time with lots of
data by Sox's meter, but I don't hear anything. If I pipe it to a file (without
-R) the file is very small and grows slowly, not what I would expect from audio. I just
grabbed a fresh copy by git yesterday but it works about the same.
A fresh run:
freebie# rtl_fm -N -f 162550000 - | play -t raw -r 32k -e signed-integer -b 16 -c 1 -V 4
-
Found 1 device(s):
play: SoX v14.3.2
0: Realtek, RTL2838UHIDIR, SN: 00000013
Using device 0: ezcap USB 2.0 DVB-T/DAB/FM dongle
Found Rafael Micro R820T tuner
Oversampling input by: 42x.
Oversampling output by: 1x.
Buffer size: 8.13ms
Tuned to 162802000 Hz.
Sampling at 1008000 Hz.
Output at 24000 Hz.
Exact sample rate is: 1008000.009613 Hz
Tuner gain set to automatic.
Signal caught, exiting!
I don't have much idea what's going on, but I'm tempted to try opening it from
a pipe (in C) to see if I can capture anything more.
Alan
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Radio Astronomy - the ultimate DX