MLAT Chunky

I’ve noticed a lot of Mlat targets are intermittant. I call it chunky, as you get a couple miles, and then a chunk of nothing for a couple of miles. Looks like morse code dashes.


This one flew over my house (east side approach to the north)

MLAT is very dependant on other receivers (M for Multi) for correct positioning, I see the same thing out past about 100km with MLAT based tracking.

Check to see how many other receivers are in your area, its on your FlightAware receiver page:

https://dl.dropboxusercontent.com/u/50785283/MLAT.JPG


Feeder Type: PiAware (SD Card) 3.1.0
Multilateration (MLAT): Supported / Enabled (synchronized with 90 nearby receivers)

Admittedly most of those are probably far away from here. I think I had only about 20 when the antenna was in the garage.

Edgy, are you running a new dongle or antenna?
You stats for today have gone through the roof. Four times any day over the last 4 weeks(not the entire month though).

Me too!

I haven’t changed the hardware for months but recently upgraded to PiAware 3.1. Maybe the different software is ignoring more dodgy data. I was synchronized with 133 nearby receivers. The black blob is my location so the aircraft went almost overhead.

https://img2.brain3.photobox.com/0304741127fbbc131d9e8366f9e26cc65fe567b85d84e4152f933b8043249b290cefb9f7.jpg

https://img2.brain3.photobox.com/53326113daa14780f278e74d09b0dca8998d355ea07efffa709a69975d44e13c79b87da6.jpg

I’ve also noted that some aircraft don’t show on the map until you select them from the list.

Note the top entry ICAO 4062D8

https://img2.brain3.photobox.com/91718861b019c08ce2bee5f60de8ab9d25e8a60e6298835c863d2c0319ea2f84b266ffa7.jpg

then clicking on the list, the helicopter appears on the map

https://img2.brain3.photobox.com/509866983396f050d6d60ada9ef29dd00f0a3b9f5c4504065d723407494a5162ebe99975.jpg

These are aircraft which you can hear messages from, but you don’t have a recent position for (and you did have a position in the past).
Clicking on the table entry shows the historical track. The infobox (not included in your screenshot) will be telling you that the position is stale.

Re the periodic holes in some tracks, this is either just coverage/accuracy (mlat server deciding it doesn’t have a good handle on the aircraft state so stops generating positions) or it’s because some servers are running hot at peak times and dropping some data. The server regions need to be rebalanced but I need to organize more hardware first, that is in progress.

(trivia: there are over 5000 mlat-synchronized receivers)

I finally got my RPi up in the rafters again. I upgraded to a power over ethernet connection (POE). So have a collinear at about 20 feet.