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Wednesday 20 September 2017

SDR and Heatmap

Not new but if you are either suffering EMC/RFI etc or just want to see how you or something else is doing you might like to note this software and comments.

I am sure many know it (dangerous assumption?). It will give you the option of scanning between a start and stop frequency and recording the location. Obviously, location depends on a good GPS RX and satellite visibility and if trying to scan the whole of the HF/VHF bands it is going to take a while but for a small 500KHz section of say 70cm it works fine so you can drive at more than a crawl. 

I used this along with a cheap GPS puck (ebay) and an RTL USB dongle (£10 from some rally), plugged into a laptop, mag mount (ebay for a 2m/70cm elcheapo one) on the roof, puck stuck to the windscreen and drove about and created a map of 70cm signals locally for an amateur
(who had an idea is was a pair of SRD TX 100m up on a pair of cranes already). The signals were blocking the output of a local repeater (20 or so miles away). After a few locals had used contest level beams from a distance to sort out the location to a few 10's of metres, I drove about the location and created a heatmap.

Anyway... it can help ID a noise source location, and/or where the signals are RX so might help some sort out interference. I have not tried but I suspect a suitable antenna on a car and a scan of one of the VDSL 'steps' from the recent VDSL survey and a drive about a village etc might be interesting.

I might write it up a bit more with images etc if anyone shows interest.
BTW yes you can use it at HF just the frequencies you start/stop on the scan HAVE to complete before you move. So be realistic if you are mobile driving.

1 comment:

Dave said...

Thanks - very interesting stuff.

Dave - M0NDT