I have installed the latest Piaware on a legacy lite version of Raspberry Pi OS. Reason I am using legacy is it is running on a Pi Zero W (Single Core).
This is intended as a portable version for visits to a local municipal airport. My initial visit showed loads of normal commercial traffic but did not see any private aircraft that were on the runways.
This local airport I would be 200-300 yards/metres from the runway and some taxiing aircraft pass yards from me. It was suggested my gain is too high for very close proximity aircraft so question is, what might be the preferred gain setting as currently set to 60 and adaptive dynamic is enabled?
I’m thinking for the local airport visit maybe turn adaptive dynamic off and set gain to 28.
I’m assuming you mean a visit to Elstree, EGTR, which is about 12 miles from Heathrow. That’s the airport in your profile.
I just spot checked some online traffic today for that airport, and almost all of it was full 1090 ads-b with position, as expected. I did see a couple small helicopters, and a likely military or police helicopter that were mode-s only. That would require mlat for position, so you would not see position for those with just a single receiver without online data. All the small fixed wing I saw going in/out of there were full ads-b.
Manual gain with a simple antenna is definitely the way to go. The adaptive gain you mentioned, with is enabled by default on new installs, is designed to adjust for a good signal, NOT to handle overloading signals. There is an adaptive burst setting, not on by default, that can handle very strong signals, but just using manual gain would be much easier for you to try.
Suggest you also look at some online data while there to see what is actually transmitting.
You’re in the UK, so you don’t have to worry about the possibility of 978 MHz UAT, like we do here with a very small number of light aircraft here in the US. That simplifies things for you.
Here in the US, the airspace around a large place like Heathrow and London would be fairly controlled. At the very least, a basic transponder with mode-a (squawk), and mode-c (altitude) would absolutely be required. EGTR is just far enough away that full ads-b might not be required, but I’m not that familiar with UK airspace. Here in the US, you can still get very close to fully controlled airspace without full ads-b.
Some have an LNA, some don’t.
With LNA probably just zero.
Otherwise 20.
If the range is too terrible you adjust the gain upwards.
It’s really trial and error.
You don’t care about long range in this scenario so having the gain too low shouldn’t be an issue.
And again if it doesn’t receive anything, just go 10 points up.
It is also entirely possibly that many of your aircraft on the ground have their transponder in standby mode, and are not actually squawking. Depending on the airport, aircraft, transponder, checklist, and even the pilot, many aircraft only squawk from immediately before takeoff until shortly after landing.
For a simple antenna, think something like a paperclip or one of the simple, tiny antennas that used to come with the RTL devices in the early days when mainly used for digital TV.
Bigger airports use and likely demand full ads-b transponder ops even on the ground for tracking. Tiny uncontrolled airfields like that could care less, and many probably taxi and do ground ops in standby mode.
In my own expirerende as a private pilot we switch from stand-by to active prior to lining up on the runway.
The transponder is switched off again at the after landing checks after exiting the runway.
For most GA aircraft this is standard operating procedure, depending on the aircraft type and the requirements of the airport where you are landing or taking off
Quite a busy municipal airport, occasional European flights, of late a Pilatus PC12 has been visiting often. Link shows image, couldn’t find one on Flightaware.
I have a permanent unit at my home address, about 4 miles from Elstree, just a portable magnetic antenna but due to my location see around 1800 aircraft per day. Heathrow traffic flies over around 8000 feet, I also have traffic from Luton EGGW and Stanstead EGSS fly over around 8-12000 feet. I see the flying Elstree traffic but unable to pick it up when low altitude, hence the portable unit - plus there is a lovely cafe at the airport.
Thanks wiedehopf for reply and advice re settings. I’ve used your github scripts before but not the auto gain one. I do have ssh access whilst at the airfield,albeit just by mobile so changing the gain and restarting dump1090 is quite easy - unless of course bright Sun and I can’t see the screen
Interesting to get a pilot feedback, I think even the big commercial jets do similar, often notice when following a flight the ads-b transmitter sometimes quite late showing on the map and same as you mentioned, soon after landing the map indicator disappears.
I’m not talking about the autogain script, that’s deprecated and way too slow to adjust for something like that.
readsb has a builtin --gain=auto now.
It’s default when you install it.
What i linked in the previous post is the readsb install script which will replace dump1090 with readsb and should just work.
Having it automatic can be an advantage as the gain will go down when a plane passes by very close and goes back up immediately after the plane has passed.
Oh right, that is interesting. Will it work OK on a Pi Zero W (single core), I do have Pi versions 3 and 4 if the Zero not up to task. Zero just very convenient for portable version, even with USB SDR plugged in takes less than 500 mA
There is a readsb .deb package available in raspberry pi repository, but unlike your version, it does NOT support rtlsdr i.e DVB-T, FA Prostick, etc are NOT supported by it.
Well it is my version (from last october), it’s just built without rtlsdr support.
Also comes without a webinterface.
Let’s see if the maintainer will answer, i somewhat doubt any changes are gonna make it into stable, but maybe the next stable
