FlightAware Discussions

Increase # of positions?

I’m #1 in my areas in planes tracked now but my neighbor is killing me in positions by almost 25%.

Any thoughts on how to increase my positions being submitted?

(Yes, I know it’s lame but I want to win.)

You can try reducing gain and see if that helps.
(Might be missing out on close in positions, what’s your Messages >-3dB percentage?)

But most likely he is receiving aircraft on the ground which increases the number of positions significantly i believe.

Also you could probably pick up some more positions to the south west, looks like you don’t have clear view of the horizon in that direction.

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Now, positions is an area where I don’t have a shortage. As @wiedehopf indicated, positions increased in numbers when the gain went down a notch or two. There’s plenty posts about gain setting. The performance graphs are a big help.
If you are close enough to the airport then the number of planes on the ground will do enough damage.

Ah, thanks. Yes, I’m about 1.5 miles away from SAT airport so that must be happening.

I currently have the gain set at the default -10, so it’s auto.

I’ll play with the graphs, thanks!

Which graphs you have?

I use
(1) RSSI column of dump1090-fa table. This column is visible after you expand the table to full width. Then twice click on the RSSI column heading to sort values high to low (0 is highest, -1 lower, -3 still lower, -20 still lower).

(2) I have installed graphs by @wiedehopf by following command:
sudo bash -c "$(wget -q -O - https://raw.githubusercontent.com/wiedehopf/graphs1090/master/install.sh)"

Please see this site for details:

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What are you doing for an antenna (and where is it mounted)?

Without a doubt, the single greatest part of your system that will determine it’s performance is the antenna (inc. feeder etc). That is, an antenna the ‘does’ perform well, mounted high and in the clear. This is not always possible, but it’s something to aim for.

Your dongle can make a lot of difference particularly if you have lots of RF in your area then a filter (or dongle with a filter) usually improves performance.

‘Auto Max’ (-10) is the setting for the ‘general population’. :wink:

You’ll be surprised by how much results change when fine tuning the gain.

What’s your hardware ‘configuration’, by the way?

Actually -10 does not adjust gain automatically because this function is meant for constant signals like digital television signals (what the rtl-sdr chipset was originally made for).

So for ADS-B it basically just uses maximum gain which is equivalent to a gain setting of around 55 which due to a driver quirk is not available via the manual gain settings.

Some more on gain: Thoughts on optimizing gain

Sorry to be slow as my whole system went down and I had to do some work stuff!

  1. Hardware is FlightAware antenna, 25’ cable, Flightaware prostick (with the amp in it), the filter from FlightAware, and a Pi B+ quad core.

  2. I am 1 mile SE of KSAT. Antenna is a 25’ metal pole I made. I’m at the base of a slight hill so the S view is slightly blocked by trees that direction.

  3. Here are the graphs for today for the signal level using the -10 gain:

Experiments to lower the gain have resulted in little/no seeming increase in either messages or spotted planes. So, that’s where I am so suggestions welcomed!

Well it may well be that reducing the gain reduces your far out positions.

Which gains have you actually tried for a day?

Set it to 38 and let it run for a day.
Set it to 42 and do the same.

Look at the number of positions in the <40 nmi range.
That’s where your direct competitor is getting many more planes.

Got it.

The attempts I did at other gain levels were using the automated script found here on the boards. Usually doing a minute or so at each gain to see what would work best. -10 was the most successful though the others were similar in results. You think doing it for a longer period is better, then?

My competitor is actually about 12-15 miles northeast of me best I can tell. Given more traffic through this part of Texas is north of KSAT, that would seem to be a help to him.

The script is bad imho.
You need to tune it yourself.

If you are at AGC right now maybe try 49 first and see how the red percentage changes.
Then try 46 for a day.

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And I want the red percentage to be 5% optimally?

You want the best SNR, not absolute highest signal. Lower the gain, most times the SNR increases, and performance improves.

The link i posted somewhere above talks at length about that.

It depends on what you want.
But as you mainly seem to be interested in improving the numbers 5% is a good place to start.

If you would rather reliably see the local traffic on your local map then maybe less is advisable.

Great. Thanks for the advice. I’ll try those recommendations.

I have an identical setup to yours and had the same issue with close aircraft overloading the receiver (I’m about 5 miles from a primary LAX departure route with constant traffic). I played around with the gain and found best results were when the % above -3 dB (the red) was between 3% and 5%. Also at this setting my noise floor trace was about 10 dB below yours, typical highest level is -28 dB or so. I pretty routinely get hits at -32 dB before losing aircraft, often below the reported noise floor.

My setup has about 5 dB of insertion loss between the FA antenna and the pro-stick plus and the optimum gain setting was 33 dB. Positions have increased ~30%, aircraft ~15%. Here’s a typical signal level plot when I have good performance.

signal%20level%20chart

When overloaded the close in aircraft will drop positions and won’t be counted. You can see this happening in the dump1090 plot where the close planes don’t show a solid trace but have gaps.

mgirdley,

You need two separate & distinct sites at your location. (ie clones of each other except for the gain)

One dedicated to long distance traffic and the other to close in traffic with the gain in each set accordingly.

Good luck!!

mgirdley,

You need two separate & distinct sites at your location. (ie clones of each other except for the gain)

One dedicated to long distance traffic and the other to close in traffic with the gain in each set accordingly.

Good luck!!

Fascinating approach. I never saw any reports of doing that on the forums. How is it done? Separate antennas, pi’s, everything?

you can use the same antenna but install a good quality splitter then use two different dongles (preferably of the same type but at different gains) and use two RPI’s. one dongle/RPI for distant aircraft and the second dongle/RPI set for close targets.
or, you can replace your current dongle with an Airspy Mini which will provide much more dynamic range. you may find with the airspy mini you don’t need two separate stations