[Ground-station] channelized FM SDR

[Robert McGwier]

A single strong FM transmitter anywhere near will collapse the front end.
A FM bandstop filter also degrades 2 meter low end and has insertion loss
that harms the sensitivity further.

RTLSDR is great but you get what you pay for

Bob


On Sat, Oct 31, 2020, 2:10 PM Phil Karn via Ground-Station
<ground-station at lists.openresearch.institute> wrote:

>
> On 10/31/20 11:10 AM, Douglas Quagliana wrote:
> > Hi Phil,
> >    Please let me know when the code is available. I would like to try
> > getting it to run off an RTLSDR dongle and try to have it identify the
> > callsigns of the repeaters that it receives.
> > 73,
> > Douglas KA2UPW/5
> >
> In principle I could use the RTL-SDR, but I haven't actually used it
> myself yet. It has a rather low dynamic range, so strong local repeaters
> could blank weaker signals on other channels within its bandwidth.
> Getting the most out it will probably require a lot of work on a good AGC.
>
> My favorite SDR used to be the AMSAT-UK Funcube dongle, but it has a
> very limited bandwidth (192 kHz). I'm now using the Airspy R2, which has
> a 10 MHz bandwidth and 12-bit sampling. This is enough to easily cover
> the entire 2m band. It can cover most of the 440-450 segment, but the
> actual coverage of SDR is a little less than 10 MHz because of
> anti-alias filtering ahead of the A/D. But it can easily cover the 5 MHz
> half of whatever segment used in your local area for repeater outputs
> (i.e., either 440-445 or 445-450).
>
> Phil
>
>
>
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