RTL-SDR Dongle and Antenna

[Paul_Sengupta]

I've got a couple of spare aerials kicking around if you want to try them, though I suspect this repair to the aerial is probably the way forward.

I'm interested in the dongle you've bought though, it's Chris's V2 low power dongle. These use switched mode PSUs on them rather than the linear power supplies on the standard dongles. I was curious about the noise generated by the switched mode PSU and whether this affects performance, but the article linked says the V2s are much improved in that respect over the V1 and that they're almost as good as the original linear ones. Still, if experience says that these are a bit "deaf" then that's interesting, though I suspect a good baseline antenna would be a good start! 

Your screenshots look ok, much improved! 

So your next mission, should you choose to accept, is to use your "knocked up" antenna with the low power dongle to see how that fares. A comparison would be good.

[francoisvl]

Thanks Paul - I'll repair the aerial when I get back from my work trip and then I'll do some testing on the V2 dongle when I know the system is back up again. I got it because I was suspicious about the dongle I did have, and it seemed like something to try out, especially if it doesn't get as hot or use as much power but I've just not had time to check it out properly. It does appear more 'blind' on the windows transponder testing software I linked to in my previous post so I don't think it 'sees' as well as the dongle that came with my PA.

Kind regards
Francois

[exfirepro]

Sorry Francois, I've been busy all afternoon and evening, hence missed your earlier post. The results definitely prove that the original dongle works, so the problem must have been an antenna issue.

I have also been trying to get hold of a couple of the Stratux Version 2 low power dongles myself for testing, but the 'Chinese' RTL-SDR store is reporting out of stock until end of January/February and I'm not keen to order from Amazon US as that normally results in significant import charges! It would certainly be useful to see the results using the Stratux Dongle, though I would be very surprised if it proves to be deaf when you try it with a working antenna - even your home made one.

Let us know how you get on when you get back.

Best Regards

Peter

[francoisvl]

Hi there - got this info back, and not sure what this means in terms of PA?:

Hi Francois,

The Stratux RTL-SDR is still a standard dongle in terms of overall function. So that means that it can tune to either 978 or 1090 MHz, you'll just need to choose the right software for the frequency you want.

Other non Stratux dongles like the FlightAware Pro+ have front end filters in them which restrict them to 1090 MHz.

Regards,
Carl Laufer
RTL-SDR.com

[exfirepro]

Francois,

Basically it means that the Stratux dongle should work, as PilotAware will set the frequency. I would be pretty sure from the tests you’ve done that the both dongles are working and the problem is with the antenna.

The FlightAware Pro + by the way is designed for ‘plane watchers’ trying to receive signals on the ground from aircraft in areas where there are very strong nearby radio signals such as mobile phone masts close to the desired frequency, so has a filter designed to filter all signals outside the 1090MHz band. As such, it should also ‘work’ for the 1090 side of PilotAware, but as PilotAware is designed for use in the air, where this type of interference is not usually an issue, this would be significant overkill. There is also no guarantee it would be any better than the standard dongle in terms of general performance and it would potentially also draw higher power as it also contains a pre-amplifier. Reducing power draw (and internally generated heat) generally improves performance, hence why Stratux have designed their ‘low power’ dongles as their system normally runs two in parallel.

Regards

Peter