FlightAware Discussions

Is this going to be a problem?

I switched my RPIs over from dump1090-mutability to dump1090-FA this morning and I must say, the GUI is a vast improvement. Obviously this turned on AGC but I wonder if this going cause more problems that it helps because although my signal level has increased, so has my noise level.

These graphs show what I’m talking about:

dump1090-localhost-signal-48h
dump1090-localhost-signal-48h-2

I ordered an RTL-SDR LNA and V3 stick yesterday because of the poor reception I was getting but I’m wondering if I really need it.

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Mean level (green) below -10 is still relatively low gain.

The LNA is probably still gonna help for the filtering alone.

Also with an indoor setup you can place it directly at the antenna and avoid the problem of cable loss.

AGC leads to the highest possible gain value, around 55. The automatic adjustment does only work with constant signals like the tv signals these dongles were originally designed for.

Try lowering the gain to see how that changes reception.

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Thanks for that. As you know, I’m new to the graphs so I wasn’t sure what I was looking at.

I’m not sure where all the noise is coming from and am trying to pin down the source.

Generally considered a good choice, but it depends on what you are using now.

Yes, I knew about that and I was rather surprised that whoever created this version decided to turn it on.

What I don’t know is whether the signal to noise ratio is good enough.

I never had access to all this information when I was running MR-Dump1090 on Windows. Although I did try various settings before settling on what seemed to give the best results.

Would I be right in assuming that the AGC will help reduce problems such as overloading from planes flying directly overhead when I get my V3 and LNA

Re what I’m using now biekerc, I have two home made spiders in the loft right up under the ridge tiles. One is centre line and one is half way between that and the wall. As I explained on FR forum I can’t put them outside because I don’t have a chimney and the TV aerial is on one gable end and had to have a scaffold put up to be installed and the other gable end is equally difficult to access.

No, unfortunately not. It would adjust to a constant signal, but with the many different short adsb signals it increases the gain until it reaches the highest value.

Which type of dongle?

Well I’ll just have to see what happens when it arrives and respond accordingly.

Thinking about it though, one of the other problems AGC would have is that the signals are coming from all different directions at different distances and altitudes.

I’ll be back.

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You’ll need to go to a gain of probably 28 or 30, it’s easily changed in the configuration file:
/etc/default/dupm1090-fa

I did everything on a budget so I got 2 el cheapo Chinese ones for about £8 on eBay. They work but then I have nothing to compare them to.

Worst thing about them is they have TV coax sockets in them so I used just used a TV coax plug on each end of the cables and TV Coax sockets to build my spiders. TBH, I’ve been surprised they work as well as they do.

I’m going to have to fork out for some fancy connectors when my new kit arrives!

Thanks for that wiedehopf.

edit:

But I guess I’ll have to set it using piaware-config rtlsdr-gain =xx on the live one 'cause it will get nobbled on reboot otherwise.

Many people started this way., I guess. Well I did. :grinning:.The RTL-SDR combo should lead to better results, then.

Apart from not being easy to put the ant outside, the terrain is my biggest problem I think.

Did you check with heywhatsthat.com?

The bane of the terrain!

Gonna move to the Wasserkuppe, the Americans knew the best locations for listening to the Soviets during the Cold War.
I wonder how much the rent for one of those leftover radomes would be :slight_smile:

Yes and it confirmed my long held suspicions.

You’d get more than just good ADS-B signals there.

I have been surprised by the way this thing has taken over my life. It all started because my wife loves (loved) flying and was always looking up at planes going “lucky devils” to ones going out and “poor things” to ones coming in. That doesn’t make a lot of sense really because there’s probably an equal number of both lots of people on most planes in Britain.

I hated flying myself because the only time I ever did it, it was for work, which is a whole other experience IMHO.

Anyway, I found the FR24 app for her and got hooked myself. Then I decided to start receiving the signals which was a logical progression given my career path really: I trained as a Radio and TV engineer when I started work in 1968 and moved into Computers in 1982. Having retired early due to ill health I needed a hobby that didn’t cost a lot to do and one thing led to another as they say.

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