Best picks for improving a UAT setup? Rather than swap out stuff over time, aiming to do it in one shot. I live near a municipal airport with a good amount of general aviation. And there are quite a few small airports within 50 miles.
Currently see 10-20 planes at once, peak on a busy day. Mostly close in, sometimes closer to the 50 mile range. That’s with a home built, 8 legged 978MHz spider antenna and RTL-SDR v4 in a window.
Didn’t find tons of material here for UAT/978MHz. This thread is good (5 years old though.) So if you have first hand experience or impressions about the brands or options below, I’d appreciate feedback! Parts I’m considering…
RF spectrum scan finds lots on 850-890MHz, scan attached. Seems a filter would be helpful.
DPD Antenna is expensive, is it really 8dBi? Might be worth it.
I’m using the 5.5dBi 1090/978 ADSBx antenna for my 1090 feeder and it works great on 1090. Didn’t seem amazing on 978. That could have been due to lack of filter and LNA with the RTL v4 in my current UAT setup. Is that antenna really tuned in the middle of 1090/978 or is it optimized for 1090? If it works well for others on 978, I could give it to the UAT setup and upgrade to the 9dBi DPD 1090 antenna for the other feeder.
I use the AirSpy Mini for 1090 and it’s impressive. Maybe that’s the best bet again for UAT? It would need a Filter and LNA, then the AirSpy 978 Filter/Preamp seems an obvious choice.
The AirNav FlightStick UAT packs a lot of value on paper with its built-in filter and LNA at $50. Anyone compared its performance to other setups?
Have used the Adsb-x antenna outdoors and in attic. May be hard to compare 1090 and 978 due to the lower traffic levels on 978 and lower powered aircraft transmitters. The FA and AirNav dongles seem comparable. The AirNavs are physically smaller and the small plastic case can be easier to damage from bending.
Have noticed that the outdoor ADSBX antenna just above the roof receives TIS data from the airport about 10 miles away. Would be interesting to try decoding FIS.
The in attic antenna sees an average of 0 UAT and max 2, avg range 2.7nm and peak range 56. The outdoor antenna sees an average of 2 UAT and max of 8 avg max range 13.6 nm max range 142. For comparison on 1090 the same outdoor antenna sees avg 78 aircraft and max 211, avg max range 127, max range 202 nm. Probably higher altitude for 1090 aircraft. Don’t know if that’s typical for 1:10 ratio of UAT vs 1090 traffic.
Thanks for that info @turbodogfl good to hear the orange and blue sticks are about the same from a reception POV, and I’m a fan of my blue FA stick so I might lean in that direction.
I found a program called uat2text which was interesting to peak at what’s on 978MHz. I ran it like this:
After making the initial post, I discovered airspy mini apparently doesn’t work with 978 since special software is needed for it and airspy_adsb doesn’t seem to have a UAT counterpart.
For now, I’ll try the Uputronix 978 specific LNA+Filter with an RTLSDR v4. I have 4 antenna’s to try it with, including the homemade spider. If the ADSBx dual band does make a big improvement in the setup vs the other antennas, I’ll be more likely to try the big DPD UAT antenna.
Clearly you guys understand FA and radio signals much better than I do. I live 3 miles from KLAS. The VOR antenna sits on the field. It’s a turn point for a/c in cruise.
I’m trying to figure out why I can pick those a/c up from 40 miles away, but when they are overhead at 30K ft, they don’t show up on FA. What is the slant angle of the FA 1090 antenna?
Depends on what antenna you are using but the higher gain omni antennas usually have more intense null overhead as they squish the toroid out towards the horizon.
You could try a really basic low gain antenna temporarily just to see if it solves your high overhead issue. I read that usually commercial flights overhead are broadcasting so strong and so close that the null doesn’t matter but if your gain is very high out to the horizon maybe it’s a strong enough null overhead to miss them.
Haha no worries. Keeping at this can make you learn a lot about antennas.
Antennas have a pattern. Omni directional see the same in all directions horizontally, but they are like a donut with a null in the middle where the gain is low or zero.
I could be wrong about this but I think it’s close: I believe any antenna has a fixed “volume” of gain. So in order to get more gain to see stronger to the horizontal distance, you lose some vertical gain. Directional antennas like Yagi’s (not used for adsb) are even more interesting. They kind of “project” their gain out to one side but then have low gain behind them.
Lower gain antennas for ADSB see less distance but better overhead.
This thread is about UAT, you’re asking about aircraft at 30k ft which are typically not UAT.
they don’t show up on FA
you’ll have to be more specific.
I’d say just try running less gain.
The lack of reception directly above the antenna isn’t that pronounced.
Typically when people complain about not receiving close by aircraft, it’s too much gain.
But yeah for more info you’d have to describe the hardware used and how the antenna is mounted, optimally with pictures.
Check https://www.heywhatsthat.com/ for your location using up in the air with 18,000ft to see what the max range you could cover since 18,000ft is the max flight level for UAT.
I’m near a few GA airports and I only see 50 UAT aircraft on a good day compared to 3500 Mode-S. Most of the aircraft from the GA airports are using Mode-S.
I’m just using a Radarbox 978 dongle and a Vannat 5/8 978 antenna, but I’ve also tried a Prostick with the light blue filter, didn’t see much difference between the two.
