Testing Signal Quality with Spectrum Analyzer?

Hi guys,

Little green here and just wanting to know how to test the signal quality and any interfering signals using a Pro Stick to Pro Stick Plus. Also understanding how to set the gain to ensure maximum signal quality.

Is this possible I have seen software like SDR# and HDR etc.

Thanks in advance and sorry if this has been asked in the past.

Have a look at this post:

RTLPan or Spektrum are both much easier to get up and running.

Your ProStick Plus has a band-pass filter built in (otherwise the same), so should attenuate out-of-band signals.
Use the ProStick to get a better idea of what is around.

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You still get a good idea of the 800 and 900 MHz bands. It is attenuated for sure but the various mobile frequencies are so strong that a single SAW filter is fighting a losing battle :wink:

I’ve been wanting to run a comparison between
ProStick Plus combined with FA filter
vs
rtl-sdr blog LNA + rtl v3 dongle

And check what the spectrums look like at the gain i use to get around -10 dBFS average signal level for ADS-B messages.

This is my scan at a gain of 38.6
Current git version of rtl_power from (https://github.com/keenerd/rtl-sdr.git)
Command line:
./rtl_power -f 700M:1200M:100k -e 30m -i 30 -c 50% -g 38.6 -F 9
(the dongle is using 1.6 GHz as a sample rate, with older versions it will use 2.8GHz sample rate)

I know it’s a bit higher gain than normal for these scans but for comparability i wanted to use the same setting i used for receiving with the same antenna (spider on the top of the roof)

Pro Stick Plus without filter (except internal) and then with the FA filter compared:

You can see the 810 MHz is practically eliminated by the FA filter but the band around 940 MHz is not reduced enough, though it is reduced.

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Completed the comparison:
1: ProStick Plus without external filter
2: ProStick Plus with added FA filter
3: RTL-SDR BLOG V.3. with RTL-SDR BLOG LNA

The weaker signal at 1090 MHz for the ProStick Plus is not a shortcoming of that dongle, just different gain.
But even with higher gain at 1090 MHz the LNA combination shows its strength at eliminating virtually all out of band noise!

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Fantastic comparison above.

I have both FlightFeeder, Pro Stick and Pro Stick Plus and filters if required so will experiment.

I had issues configuring SDR# when I tried but hopefully with all your assistance I will be able to get it scanning and I can start eliminating interfering frequencies.

Appreciate it guys thanks

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The RTL-SDR BLOG Lna seems to work pretty well.

I had a spare v3 dongle so I ordered one, not expecting much, but it actually improved reception further away and in less favourable directions ( wall, hills).

Message rate overall is higher, too, compared to a Pro Stick Plus + a sysmocom cavity filter. Got rid of two adapters, too, maybe that helps a bit as well.

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Has anyone got a pre built Raspberry Pi image that is used for Spectrum Analysing.

My computer doesn’t seem to like the USB drivers used by Rtl# etc

Might just build one using raspberry pi instead

No. What is the problem with the instructions linked in post #2 of this thread?
Talking about the OPTION 1 for the raspberry pi?
It’s quite detailed.