FlightAware Discussions

A balance between distant and local

Well the initial test setup is running complete with graphs etc. Currently using a pro stick and a home built coco and for a roughly built one, quite surprised really. I housed it in some PVC pipe with the base big enough to house a LNA which I have but no Bias Tee yet (on its way) so haven’t put it in. Not sure if this will overload the prostick. Also have a filter coming to put inline just before the stick.

So in reading various threads etc there is a balance between receiving distant transmissions and local ones. How many of you run 2 units with one having its gain wound back for local and one having it at whatever to achieve reliable distant stuff?

I was thinking about using a splitter between the inline filter to feed 2 dongles

That cannot be done because… multiple reasons.
If you think you have issues with the distant/local airplanes, the solution is to get a receiver stick that has bigger dynamic range, like the Airspy ones.
But, in my experience, that is seldom the case. Better filtering (LNC with 1090MHz filter) helps a lot in this respect.

You may be interested in the “adaptive burst” gain control which will be in dump1090-fa 6.0. Essentially, when enabled this turns down the gain when there are loud signals seen that are not successfully decoded. So it trades off range for nearby signals when nearby signals are present.

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This sounds very interesting. Any idea when it will be rolled out?

What is the general definition of “near by”? Which distance is it in general?

I do have aircraft passing my location directly with an altitude less than 5000 feet. So i assume this is not “near by” as i do not have any drops?

It’s currently planned for some time in August all going well.

It doesn’t look at position/distance at all, just signal strength. (It’s basically looking for bursts of strong signal levels above -3dBFS which are not part of a decoded message and which look like about the right length for a Mode S or ADS-B message)

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So “adaptive burst” gain would allow one to tune gain for maximum range without over powering the receiver and losing “nearby” traffic? That seems to be a win-win.

The tradeoff is always there, you can’t receive both simultaneously. The idea is to automatically turn down the gain only when you need to (and then turn it back up afterwards)

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:+1: This is great.
This will be the real AGC which the dongle’s gain setting agc/-10 have failed to achieve.

Wow, that is already within a few weeks. Reading the comments I am not the only one who s excited :blush:

Is the next gen FA receiver/stick also still on the horizon? (Asking for a friend…)

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Yes, though the global semiconductor supply issues have really slowed us down there.

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So is this something that will be implemented in the FlightFeeder, FlightFeeder USB sticks, or are you guys referring to the pi configs?

I kind of hope not! I just bought a FlightAware Pro stick to replace the NESDR SMArt I’d been using. It was just delivered yesterday evening.

One can never have too many sticks!

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[quote]

One can never have too many sticks![/quote]
True. So far I’m getting worse performance from the Pro stick than I was with the NESDR, fewer messages and less range. I’m currently running wiedehop’s autogain1090 script to see if that helps. If not, I can fall back to using the SMArt stick for ADS-B again and just use the Pro for general monitoring with my SDR app, I guess. (And I haven’t figured out how to reply with quote in this Discordlike thing.)

There are a few sticks performing better than the FA stick, but i am a bit surprised about yours without a filter on 1090 MHz

@foxhunter: me too. I don’t have a filter yet. It should arrive in a week or so. Right now the FA Pro’s connected to a cantenna via around 4 meters of RG6 then to my computer downstairs with a 10 meter USB extension. This is the same antenna and configuration that I was using with the NESDR until yesterday evening. I was getting a maximum range of around 180nm and message counts in the high thousands. Now it’s 100nm and the low thousands so far. I think the new dump1090-fa v6.0 will fix my woes though, because I’m sure they’re gain-related. It could be that with that short of a coax run I didn’t really need the LNA that’s built into the Pro stick and its front-end is getting overloaded, but at the time I ordered it I had an extra 10 meters of coax between the antenna and dongle (since replaced by the USB cable.)

Lower range is usually not a gain issue but an interference issue.

You got an orange stick? :frowning:

The FA sticks use a bit more power, might be that the long USB doesn’t give enough power to the FA stick and that’s why it’s not performing well.
Put the pi where the SDR is now?

That’s a very good point i did not remember.

I used a USB-Cable of lower quality and the performance of the stick dropped by 30%
Once i exchanged it with a different cable, the perfornance came back to the values without any cable in between.