On gain -10 (AGC), right now about 440 m/s.
Changed to 30, down to 380.
Changed to 20, down to 180.
Changed to 40, up to 460.
Changed to 50, down to 390.
AGC seems to be close to optimal.
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Looks like you rounding up/down the levels. Based on the numbers you posted, I would try all levels above 40 but below 49.6. My guess is that 48.0 will work best.
Yes you’re correct, I just typed that into putty and let the script round to the predefined list.
I just bought the filter as well, will test when it comes with the new antenna. I have three pi setups I can run concurrently to check all combos of FA sticks, generic sticks, the antennas and filters.
Wise action
Did you run RF signals scan as shown in thread “Do I Need a Filter?”
These are the spectrum using the cheapo antenna.
Flightaware Pro stick with built in filter:
Generic dongle
Ok, good, but what about scan with FlightAware Antenna? Being high gain (6 dBi), FA antenna catches cell/mobile signal much stronger than the low gain (2.2 dBi) cheapo pcb antenna catches.
Running now actually.
Is the scale on the last graph correct? The plot matches the first one, at different frequencies, not likely.
Scale differences aside, there is something wrong with the FA antenna setup. If not the antenna itself, connectors, adapters, pigtails, cable.
Are the gain settings the same. The generic dongle does not look too bad, less than 5 db difference compared to the the Pro Stick. There must be something else causing these changes.
Yes, it had the autoDB checked in the program.
The 1st graph is with one FA Pro stick, the 2nd graph is with my other FA Pro stick. I will swap them around and rerun the scan.
New antenna will be here on Wednesday so I can test, otherwise the only thing left is the cable (there are no converters in between, straight N to SMA). I have a N to MCX adapter coming Wednesday as well so that I can use the same MCX cable the cheapo eBay antenna is using to rule the cable out as well.
Autodb (AGC) is not a good setting for this type of comparison. In addition to that, there was a discussion some time ago saying that AGC on ADS-B is not a good idea. There reason it exists as an option is because the dongles where designed for wideband TV signals.
The second graph is not a generic dongle then?
That is the worst thing to do when running scan to compare setups.
I mean, the autoscale. It was set to 49.6. Sorry about the confusion.
edit: yes, manually set to 49.6, AGC is unchecked, Auto DB checked means the scale is auto set on the program for the graph.
If you are re running scan, set gain mid-way, say 24 dB.
Yes, he is compressing at the top. Mid-way will show the antenna and dongle gain differences properly.
Tell us who is who? Same dongle type used for both scans? Hopefully the first one is the FA antenna. If not there is a problem. No way the FA antenna is 16 db+ worse.
Those two are the same FA Pro stick with the FA antenna. The graph just changes as it runs through the frequencies, I took two screenshots within the 15 min scan.
I’m looking at the raw csv file and it only has a snapshot of data in there at a specific time stamp, i.e. 16:12:59, and that’s it. I’m not sure if it is continuously tabulating data and building an image from there. I don’t see any options in the GUI either.
The results do not make any sense. The scan should be cumulative, not instantaneous. The drawing of the graph should be persistent, basically adding all samples from the period it ran.