I just downloaded the RelWithDebInfo precompiled windows software that was posted on Oct 24th. I am using an E4000 dongle which has a PPM of +30.
I am trying to listen to 424.175MHz and I'm using this:
rtl_fm -p 30 -d 1 -N -o 4 -f 424.175M -s 16k -C|sox -r 16000 -t .raw -e signed-integer -b 16 -c 1 -V1 - -d
everything is playing fine. I can hear 424.175MHz. The issue is that I'm hearing another station 50KHz higher on 424.225Mhz in addition to the frequency I want. So it looks as if it's not using a 16Khz filter. Am I doing something wrong or is there an issue with rtl_fm.exe? Thanks
Chris
On 10/28/13, Chris Hanson lightningbolts@gmail.com wrote:
I am trying to listen to 424.175MHz and I'm using this:
rtl_fm -p 30 -d 1 -N -o 4 -f 424.175M -s 16k -C|sox -r 16000 -t .raw -e signed-integer -b 16 -c 1 -V1 - -d
That looks correct.
The issue is that I'm hearing another station 50KHz higher on 424.225Mhz in addition to the frequency I want. So it looks as if it's not using a 16Khz filter. Am I doing something wrong or is there an issue with rtl_fm.exe? Thanks
It is a minor issue with rtl_fm. The (very fast) downsample filter tends to leak in places. Soon this will be replaced with better filters.
There is a better/slower filter that can be enabled with -F. Check your --help and confirm that -F is present and says 'hamming' in the description.
-Kyle
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Chris Hanson -
keenerd