Re: Looking for SDR idea suggestions.


Greg Ella
 

SDR receivers convert an entire block of spectrum into live streaming I/Q data
that can be processed in real time.  That's why we get the nice real time
spectrum display, and why we can record an entire band to hard drive and
"tune around" inside of it after the fact.

Most modern SDR receivers can cover over 4 MHz of simultaneous bandwidth, which would cover the
entire span of any of our Amateur bands until we get up to 70 CM.  Even there, I think that the band plan for
specific uses, live FM Simplex or Repeater Output, is less than 4 MHz wide.  If not, there are some
receivers, like BladeRF, that can cover 30 MHz or more of bandwidth.

Given the above, it seems to me that your approach, scanning across frequencies one at a time with a defined step size,
would be a step backwards.  Think of older spectrum analyzers that used swept tuning, vs modern RTSA analyzers.

I think that what would be useful here is an application that lets you set a frequency range (within the maximum bandwidth
of the receiver), the trigger level, and the demodulation mode.  The software would detect any signal that pops up above the detection level,
snap to it, and pipe out demodulated audio.  As a bonus, it could trigger recording to an audio file, and the recording would be time, date and frequency
stamped.

Does anybody know if such an application exists yet?

Greg Ella
N0EMP


On Sun, Nov 28, 2021 at 7:07 AM KD7JYK DM09 <kd7jyk@...> wrote:
I've looked online on and off for a year or two, and haven't found an
answer, or example to an idea I have.

Something along the lines of a scanner, or scanning, but an entire band,
for example, 10m, or 20m, and if a signal is above a threshold, the
receiver will stop on the frequency.  Frequency would be unknown, so the
entire band in reasonable steps for the mode.

Think of it as an old analog scanner search function, set low frequency
limit, then high frequency limit, press search, something pops up,
scanning stops until transmission ends, then continues.  The idea is, if
there are close, or strong signals on a band, such as a local net, or
going into an area with some activity, but not sure where it is, the SDR
could track it, so to speak, mode, AM, FM, SSB, et cetera, could be set
after the first few hits.

 From what I understand, an SDR is fast, so it seems if a signal pops up
anywhere, and was above a threshold, searching/locking, then continuing
would be nearly instantaneous until the next transmission

Anyone doing this already?  I've found mention of people using some SDRs
as a scanner, and putting in a few frequencies, like channels to search
through, but I haven't found any references to sweeping all of 10m.

Ideas?  Looking for examples of SDRs that can do this, software, some
basic settings.

Thanks.

Kurt





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