Dynamic range questions

I have an application that must operate in the 25MHz to 40MHz region,
with a channel having a nominal bandwidth
of 50Khz to 700KHz or so. The Rx center frequency may be anywhere in
the 25MHz to 40MHz region.

My question is about dynamic range requirements when operating a
receiver in that neighbourhood of the
spectrum. It’s not a neighbourhood I’ve habitually “hung out” in, so
I don’t have any intuitive feel
for how crowded it is, with emphasis on the Rx being in “deep rural”
locations. My suspicion is that
things like GSM receivers have a much worse time of it, and do OK with
14 bits of A/D.

Is it likely that I’ll need to do narrower analog filtering in the RF
front end, to avoid dynamic range issues? It’s more convenient
if I don’t have to do that, but specific Rx locations could have
analog filters installed to more closely match their
specific Rx frequencies.

Cheers


Marcus L.
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org

On Sun, Aug 15, 2010 at 19:12, Marcus D. Leech [email protected]
wrote:

I have an application that must operate in the 25MHz to 40MHz region,
[…]
It’s not a neighbourhood I’ve habitually “hung out” in

The 30-40 MHz region is typically very quiet. Much of the radio
traffic that used to exist there (LMR stuff) has moved up to 150-170
or 450-470 MHz, to avoid “skip” during sunspot cycle highs.

The strongest emitters I’ve seen between 25-30 MHz are shortwave radio
stations and 10M amateur radio band contesters. Well, there is the
citizen’s band radio allocation at 27 MHz one must contend with as
well.

Johnathan

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