Testing ARF with a TV tuner

[tj80]

Hi,

I guess lots of people will be in a the same position as me - having built a unit which appears to be working but with no way of testing the ARF as there are no other units near by.  Is there any way of testing the ARF is transmitting using the TV tuner - such as via SDRSharp?  Obviously it won't help test receive but will at least show the Pi is talking to the ARF?

Cheers,
Tim

[Admin]

easy to rig up the following

http://www.ebay.co.uk/itm/FT232-Brush-USB-To-TTL-Serial-Cable-Line-Electric-Adapter-FTDI-Chipset-Computer-/281739777265?hash=item4198ffd4f1

https://www.wirelessthings.net/erf-0-1-pin-spaced-radio-module

voila, a simple test rig, just setup the parameters on the ERF and it will receive the ARF data

[tj80]

Hi Lee,

Good point - although that's the cost of a future years' subscription for something which would probably only get used once.  My soldering's not that bad!    I just wondered if the DVB stick could be plugged into a PC running SDRSharp, tuned to the same frequency as the ARF (868.whatever) and see something coming from the ARF even though it can't decode it.  Presumably the ARF transmits regularly so we should see regular short bursts of signal on that frequency.  I know scope creep when I see it but the complete PilotAware could even do some kind of self-test by transmitting from the ARF and receiving on the DVB stick.

Cheers,
Tim

[Admin]

I recall somebody was using and SDR_RTL to decode the PilotAware traffic, I will see if I can find the email thread

[grvbc]

I've done exactly that to confirm that the ARF is spitting out data, but not to decode the data itself, but this was for my own use (not as a test for the PilotAware connected ARF, but it should be exactly the same).  The same RTL-SDR can be used as a crude spectrum analyser and you can quite quickly check that working using some readily available software. 

I'm using Linux and there's package called Gqrx suits that.  I've not tried but this: http://sourceforge.net/projects/guiforrrtlpower/ seems to be a similar thing for Windows.

All I did was plug in the RTL-SDR dongle and tune the Spectrum Analyser to 869.4Mhz in Normal FM mode with a Medium AGC speed.  Bingo! - there was the data being splatted out at 2 second intervals. Stops when you pull the power.  That was showing that something was being sent.

Are you thinking of using a second RTl_SDR to decode the P3I sentences?  why? 

[tj80]

Thanks - ran up the PilotAware with an old E4000 SDR dongle and SDRSharp tuned to 869.400Mhz and as you say there's the burst every 2 seconds.  Looking good - just need to wait for the right SDR dongle to arrive from China now as the E4000 doesn't work.

Cheers,
Tim

[ianfallon]

Hmmm - two of us got together to test the ARF side of things today with no avail.
I've also tried using that sourceforge spec analyser app with no joy, although I have no idea if that is working either.
If anyone has any further ideas on testing the ARF side I'd be interested. I don't have any fancy test equipment!

[tj80]

Worth trying SDRSharp running on a PC with the DVB tuner attached - it's very easy to use and will at least tell you if the ARF is transmitting something.

[ianfallon]

Thanks - will try that later tonight.

[seabeggar69]

All above should work

Just build 2 units and go to either ends of the field..that will work to 

[Admin]

Hmmm - two of us got together to test the ARF side of things today with no avail.
I've also tried using that sourceforge spec analyser app with no joy, although I have no idea if that is working either.
If anyone has any further ideas on testing the ARF side I'd be interested. I don't have any fancy test equipment!

Hmm, thats a shame, need to work out a standard test rig using SDRsharp I think !

[ianfallon]

I can't get anywhere with this SDRSharp thing either. Does anyone have a reliable step by step way of doing this ? I'm at the end of my tether with it all! I see nada on the graph thing I just get "Cannot access RTL device" when I press start and all the various options are all Greek to me.

If I don't have the ADS-B dongle connected to the Pi (because it's connected to the laptop) will the Pi still activate the ARF transmit without it ? The Pi is saying SDR-USB: Error, connect() over and over of course.

P.S with everything attached to the Pi this is the boot sequence I get ...

Does this look like the ARF is working ? Is it possible to tell ?

[trapdoor]

Ian,

You have the ARF-RS232 Configuration OK so the RPi is talking to the ARF module.

It doesn't start to transpond until you feed it GPS data with the app or the GPS/NMEA app - once you kick these off, then the ARF starts to ping out.

I am fortunate that I have a 2 Gig DSO with FFT so I can effectively use it as a spectrum analyser, but to be honest I just tune it on my comms receiver as its quicker than setting up the scope - but even a cheapo scanner that will tune up to 1GHz set to WFM should be able to pick up the data burst. Do you know anyone with a scanner?

Don't suppose you are anywhere near Bristol are you?

[ianfallon]

Thanks trapdoor - no one I know and nope - near Banbury.

[ianfallon]

Problem solved thanks to Ben flying over with his unit on and both of us seeing each other :-)
Thanks Ben!