SDR lab test set

💬 Chat about SDR or radios in general.
RF-eng-John
Posts: 3
Joined: Thu Apr 20, 2023 9:56 am

SDR lab test set

#1

Unread post by RF-eng-John »

Hi everyone, new here, and pretty new to SDR despite being an lifelong RF engineer !
I'm looking for a recommendation of hardware and software to set up a lab based test set, here's what I'd like to do...

I have a small low power FM Tx with a carrier freq ~400MHz transmitting 'audio' data
I've been using a Nooelec NESDR Mini2 with HDSDR software to see the received spectrum/noise floor etc ..... but i'd like to improve my SDR set up to do/see the following.....

Receive my ~400MHz FM, demodulate to extract the audio component (with the lowest noise floor possible), and be able to record the audio (and maybe the spectral stuff) to my laptop in .wav or similar.

I can then expose the FM transmitter to controlled vibration and/or Electrical interference, to see if there is any degradation.
This is intended to be a simple bench test to find any potential problems, not something to replace a EMC Test facility !

Any recommendation on SDR and software gratefully received, thanks

User avatar
KA1GJU
Posts: 257
Joined: Tue Aug 11, 2020 2:16 pm

Re: SDR lab test set

#2

Unread post by KA1GJU »

Airspy products are VERY good, no silly drivers to load, just plug n play if running W10 or W11.
https://airspy.com/airspy-r2/

The RTL dongles, as cheap and tempting as they are, are a royal PIA to set up.

I have an Airspy R2 on my Super Station #4 Server if you want to play. It's on a Diamond X-500 at ~45'AGL atop a 243'MSL hill in SE NH (FN42mw).
There are three repeaters and an APRS Digipeater nearby so at times it will get overwhelmed with RF.

73 Kriss KA1GJU
73 Kriss KA1GJU Home of the KA1GJU Super Station SDRC Servers in NH, USA (FN42mw & FN43na)

RF-eng-John
Posts: 3
Joined: Thu Apr 20, 2023 9:56 am

Re: SDR lab test set

#3

Unread post by RF-eng-John »

Thanks for the Airspy recommendation
Please just confirm the Airspy will demodulate to Audio, and this audio output is 'accessible' for me to record and analyse separately
Many thanks

User avatar
KA1GJU
Posts: 257
Joined: Tue Aug 11, 2020 2:16 pm

Re: SDR lab test set

#4

Unread post by KA1GJU »

The Airspy units as well as the cheap RTL Dongles are all SDR's. They are Software Defined Radios, as such, they are nothing but A-D converters. They convert RF receieved from an antenna in a user selectable bandwidth (within limits of the SDR's hardware) and digitize it into an IQ stream of data via USB. The computer software does the heavy lifting of taking the digital stream and converting it into useful modulation such as AM, LSB, USB, DSB, CW, FM, etc. Once demodulated, you can simply output it to speakers. SDR Console, the software, has the ability to record the IQ data so it can be played over and over and can demodulate the data in one of the above forms. You can also just record the audio only, but in the selected demodulated form. One can also use VAC (Virtual Audio Cables) and route the audio to various software pkgs to perform other tasks with the audio.

Clear as mud?

73 Kriss KA1GJU
Home of the Super Station SDRC Servers in SE NH, USA (FN42mw)
73 Kriss KA1GJU Home of the KA1GJU Super Station SDRC Servers in NH, USA (FN42mw & FN43na)

RF-eng-John
Posts: 3
Joined: Thu Apr 20, 2023 9:56 am

Re: SDR lab test set

#5

Unread post by RF-eng-John »

Many thanks for the explanation, now much clearer !

Post Reply