Re: New updates for SDR#, libairspyhf and Airspy HF+ (Discovery) Firmware #announcements

Dana Myers

On 7/12/2019 11:25 AM, Joe M. wrote:
Why are you using a BW of 20 kHz? If this is a normal NBFM FM ham transmission, it should be not more than 16 kHz. That will likely help.
(if by some chance it's SNFM, use 11.2 kHz)
Thank you. I'm using a BW of 20KHz to allow for stations off-frequency.

I sometimes monitor 144.39MHz (APRS) and collect 2GB of discriminator
audio at a time, then batch-process this in a homegrown program.

A useful trait of SDR is true DC response, so frequency offsets appear as DC
offsets, with a minor calibration, it is easy to get a very good estimate of
transmitter calibration (yes, I appreciate that is relatively to my receiver
calibration). This was really just a matter of curiosity, but I did find one
station that was -5KHz offset - and would not decode with the tighter
IF BW. (I contacted the station operator and he was surprised to find
that he'd bumped the frequency knob on the radio, was quite

Another fun thing I did was look at PLL bounce at the beginning
of transmissions, but that's another topic.

Dana  K6JQ

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