Since yesterday, 01/21/22, at around 1330 MST I have noticed a substantial increase in MLAT positions. These seem be coming from non-military aircraft, both commercial and private.
Usually it’s just military aircraft that are MLAT for me.
The number of MLAT aircraft does not seem to be scaling up. The ‘new’ MLAT aircraft are fairly close to the local airports KDEN, KAPA, & KBJC.
Looking at my Flightaware stats page my MLAT reported positions from 12/23/21 - 1/20/22, I averaged 487.4 positions per day. Yesterday I had 5384 and so far today I am over 18,000.
Could this in some way be related to the 5G turn-up that happened earlier this week in the US?
edit: 5G does not seem to be the issue.
I upgraded from 6.1 to 7.1 at around 1200 today. This did not appear to change anything. I did not upgrade because of this observed issue.
Funny you would mention KDEN. I’ve long had MLAT issues and it is looking more and more like it has been White Sands GPS jamming. Anyway, @wiedehopf has been helping troubleshoot and he gave me a link to a set of filters on an Adsbexchange map view that shows aircraft with GPS issues. When I was getting red MLAT flags, planes all around there light up on this map when White Sands jams GPS.
I looked yesterday and saw lots of aircraft on that map around KDEN. Just checked and even right now they are showing GPS issues. Just took this screen grab. It’s the only place in the US showing this right now.
To see them all clustered around KDEN like that was interesting. Something is affecting GPS signals in that area but no idea what. I was checking around to see if anyone else had noticed.
Thanks for the information. So the 5G rollout does not appear to be the issue.
Based on that, I dug out my Dual XGPS160 that I use for drone flights with my ipad. The signals looked fairly typical for both the American and Russian GPS satellites.
Right now I am tracking ~60 aircraft 13 are showing as MLAT, 11 of those are commercial aircraft and the other 2 are private aircraft. The closet is 12 miles away from me and the farthest is 95 miles away from me. They are in all compass directions from my location. I am located ~23 miles southwest of KDEN.
I finished the day with 25,872 MLAT positions. That’s 53x more MLAT positions that usual. There was no discernible increase in the MLAT aircraft count.
It’s localized low level jamming, otherwise you’d see higher flying aircraft in that picture.
You wouldn’t be affected by the jamming signal if it’s that localized to a specific area.
Even if it would be a higher power signal, you’re much less likely to be affected on the ground if the jamming transmitter is also on the ground (line of sight).
Just checked and at least right now, whatever was affecting GPS signals around Denver has stopped.
Yesterday when the issue was active, I checked SkyVector to see if any NOTAMs were in effect but I didn’t find any. There is a web page where GPS anomalies can be reported and a list of reports but I didn’t see anyone reporting GPS issues around KDEN or really anything for the last few weeks. I didn’t feel I had enough information to file my own report.
Hi Sadeep, it’s off topic for this discussion but the ADSB signals are largely line of sight. If you have buildings or hills between your antenna and the airplane, your receiver might not hear it. That’s why high antennas work better than low ones. Another effect can come with receiver gain. If gain is set high to see planes farther out, nearby aircraft can have their signals be so strong that your receiver can’t decode it. The new software can autorange but there are limits to how it behaves, or it might be set to manual gain and if too high, near aircraft swamp out.
There’s other threads here that probably already discuss situations like yours that might be helpful or you could start a new one but be sure to add more details on exactly what you are seeing and why you are asking for help. Good luck!
Sadeep, if I understand correctly you are asking why you can’t receive signals from the ground from your nearest airport even though you are “in range”. Are you within within 10miles/16km from the airport? Any further than that you wont be able to “see” the ground as it will be over the horizon. (this all depends on your local geography and obstacles etc. etc. You can receive planes from over 200miles away up at 30000 feet because they are still “visible” to your aerial. Any lower and again they are below the horizon and will not pick up. Planefinder has a very clever view of range… See attached. Hopefully the 3D effect is apparent? Your coverage is like a cone upwards…
This is what you would expect.
The ground level at distant airports will be well below your horizon because of the curvature of the earth. Aircraft over those airports will only appear above your horizon and become visible when they are high up. The further away the airport the higher the aircraft will need to be for you to see them.
Forgive me if I am mistaken, but can you clarify that you are not confusing Airports with the “MLAT stations synced” The listed stations are other ADSB receivers such as yours. Those are “in range”/synced, as your ADSB site and their ADSB site can both see the same airplanes up in the sky. (someone can explain better than I, I am sure)
Again see replies above, planes on the ground 10+miles away will be below the horizon. And planes at lower levels at 50+ miles will be below the horizon also.
Again, apologies if I am mistaken, but I feel we are not on the same page here.
Sadeep, you really need to stay on topic for the threads you post in. This thread was about MLAT. I tried to get you to start your own thread since your question had nothing to do with MLAT and you did, but you came back here to further derail this thread. When you mix topics like that it makes all information harder to find and defeats the purpose of these boards.
From my knowledge MLAT is showing you aircraft which are either out of range for your device or where the MLAT quality is higher than the ADS-B signal of your device.
I am using a Jetvision AirSquitter which is MLAT connected to the Jetvision network.
This is my current map of the device. The arrow points to an aircraft which is close to the max range of the ADS-B signal of my receiver, so it is shown via MLAT as the source is more reliable fo this aircraft.