FlightAware Discussions

Comparison of different dongles for 978 MHz UAT reception

Has anyone compared different ADS-B dongles for performance RTL-SDR silver V3 vs Piaware Orange, etc?

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I did this last year and I found that the Flightaware pro stick (Orange) was better since it has the built in LNA. I hate to say it but the Orange prostick also works great for ACARS reception at 131 Mhz.

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Any results like max range, flights/day?

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For ADSB the Flightaware prostick (Orange) outperformed the V3 dongle in ADSB reception.

The UAT demodulation seems to like less gain, so i doubt the orange stick will perform much or any better than the v3.

Or to say it differently, the orange pro stick will probably have to be around gain 28, while the v3 will be fine at around 48 probably.
That is assuming you are not using an additional amp.

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For my UAT reception I use the Pro Stick but with the older flight aware blue filter. I usually average 70 miles with general aviation but I have actually had private jets that gave me ranges out to 179 miles.

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This is what showed up last week. 1 up to 100 miles. But at most no more than 3 UAT aircraft. And not there all the time, so am not sure if the setup needs to be rebooted. RTL-SDR V3 with FA 978 antenna

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I know that FA said that the filter is dual-band, and certainly your results seem to back that.
However, measured in some other place, I saw it less than optimal at 978MHz, they say that blocking started at around 980MHz.

https://www.rtl-sdr.com/review-flightaware-ads-b-antenna-and-filter/

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I’ve just measured one I have here and it looks pretty flat between 978MHz and 1090MHz.
It’s about 2dB down at 930MHz and 20dB down at the top end of the US 850MHz band at 893.8MHz
See attached.

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Awesome, thanks! That means I can use mine for UAT 978MHz.

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Unfortunately my UAT pi crapped out so I don’t have previous graphs to share but what I have found, in the NYC metro area is: The Orange stick seems to provide the best overall performance vs the blue stick & the RTL-SDR v3. I’ve been adjusting the gain between 24 and 18 with pretty good results.

My current config is homemade UAT spider -> FA filter -> orange dongle -> pi3b+ (all elements of the rig are contained in an ip65 box, minus the spider which is mounted just outside the box)

I just today moved the UAT rig out to the roof - so I’ll probably run a new set of tests between all 3 dongles (and make sure to have rpiclones of the system :wink:

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Really no need to test a stick with a 1090 MHz SAW filter.
Those are narrow and will attenuate 978 MHz too much.

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This actually brings up another question: has anyone done a comparison of the FA UAT antenna vs a spider or other? I searched around and didn’t immediately see anything. I’m going to be relocating this rig in a few weeks and was debating putting a UAT antenna up next to my ADSB antenna to eek out a few more positions.

A better antenna location can make more difference than changing the antenna. Also nice if your antenna is in a location that is less likely to attract lightning or get blown off by storms. Another question might be how long you could run a USB extension cable to shorten the RF cable.

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Aircraft altitude makes a big difference. I watched two single engine aircraft flying in and out of our local airport training pilots for Central Texas College and I actually see them taxiing on the map. First time for everything. ALso once the fall sets in and we start loosing leaves we will see a difference at greater distances since some of the obstructions will be out of the way, naturally.

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I am running 150 ft of RG6 coax cable for 1090MHz without problems. Sure, I have an amplifier at the antenna end, but it works.
150 ft of USB cable? That would never work.

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There’s some good discussions in other topics related to “antenna height” Too bad the list of sites by aircraft count doesn’t add any details like antenna/dongle type and height.

Have just switched UAT from RTL-SDR V3 to Piaware Orange, should have something to compare soon

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Are there any shell commands to help you see signal quality of received UAT messages? If so can it be used to judge if gain should go up or down? There was some discussion of adding RSSI to uat2esnt and uat2text, but am not seeing RSSI from uat2text or uat2esnt. Will have to wait for the UAT signal level graphs to populate. https://github.com/KeyserSoze1/dump978/commit/46fbc54f24822e14784cb988d8b413c32a6236fa

Did you try this fork? It has RSSI added.