FlightAware Discussions

ADS-B feeder question

I setup a feeder with rtl-sdr dongle with an lna amp. Using FA antenna with LMR400 on a 20’ mast.

So my question is, do pilots see the feeder location? I have noticed a lot of air traffic in my area mostly C172s. Not sure if pilots notice the feeder or I’m just noticing the pilots now.


They won’t know unless they have this page open: https://flightaware.com/adsb/coverage

Broadcasting on 1090 MHz would be illegal, and your rtl-sdr dongle is not capable of broadcasting anyway.

Also most small planes don’t have any ADS-B reception capability.
(Well i guess there are quite a few small planes now with ADS-B in for traffic avoidance)

Yeah, no transmit. Basic FA Pi install but I do have MLAT and Mode A/C enabled. Once and a while I can hear a plane that the feeder doesn’t pick up but not often. I noticed the signal drops when they are directly overhead. I’m guessing it’s the location of the transponder in the cockpit.

[quote=“YatesRandall, post:3, topic:54641”]
I noticed the signal drops when they are directly overhead. I’m guessing it’s the location of the transponder in the cockpit.
[/quote]Sounds to me that the gain is too high and you have to lower it. Very typical with a setup like yours

You should play around with it for a while or use the automatic script of wiedehopf

The antenna does not have coverage on top.

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Well, that spot is really small. Most people mentioning this problem are talking about losing the plane because the signal is too strong. Don’t know which problem Yates is having.

See this post: Diversity Reception

Are you talking planes at >20000 ft or low flying planes?
Also see the link i posted above in regards to that blind spot.

Of course different antennas are different in regards to that spot.

Low flyers. gain is 25.4.
I plain to move the LNA to end of coax vs next to dongle once i build a weatherproof unit.

That sure sounds like the signal is getting too strong.
But eliminating that problem will probably reduce range.

The normal dongles just aren’t able to receive very weak and very strong signals at the same time.

Unless they are $99 ones :rofl:

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re the $99 dongle. i had this issue (overhead dropouts) until i purchased the $99 dongle (Airspy mini). @wiedehopf was very useful in helping me set it up in place of the RTL-SDR v3.

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And at least 12 bits ADC.:wink:

I ordered one of the following yesterday, claims to be RSP1 compatible:

I won’t use it for ADS-B though.

Hmmm… tempting. I wonder if is real or just a flop.
$44 on Aliexpress to find out, I guess… Or not.


Hm, there are other offers for this which are twice the price. I would not do that.

Note that, on the original RSP1A, the “14 bit” accuracy is only achieved at less than 6MSPS bandwidth:
At 10MSPS bandwidth, the accuracy drops to 8 bit:

The Chinese clone it cannot be different.

BTW, Airspy mini has 12bit ADC @ 20 MSPS (10.4 ENOB, 70dB SNR, 95dB SFDR):

The chinese clone is not an RSP1A, it’s a clone of the RSP1. The 14 bits option is available on the newer RSP1A only.

There are a couple of other improvements on the RSP1A, I had one, but switched to an AirSpy HF+ Dual Port.

The ‘missing’ features of the discontinued RSP1 are not important to me.

Anybody thinking of buying something like this, I suggest the new AirSpy HF+ Discovery, if HF and VHF with 660kHz alias free waterfall are good enough. For ‘DC to daylight’, and up to 10MHz waterfall, the RSP1A is still the best value around.

Actually, the chinese clone is better than the discontinued RSP1. It’s in a metal case, and has a 0.5ppm TCXO. The RSP1 did not include those.

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Received the MSI.SDR last Friday. Well worth the money. Performance is great. The only caveat, but this applies to the the RSP1/RSP1A as well, is the presence of strong MW BCB nearby.

I have a couple of RTL-SDR Blog MW BCB filters, installed one, problem solved.

From Nooelec Nesdr to SDRPPLAY RSP1