Daily mlat dropouts

I’m seeing mlat dropouts at around 10:00-12:00 fairly consistently every day. Normally there isn’t anything untoward in the log, but today there is mention of some UDP packet loss.

What’s curious is it’s also affecting the 3 closest MLAT enabled receivers to you.

Due to the collaborative nature of MLAT, its possible an issue with one of your “neighbors” is causing your area to have insufficient coverage for MLAT periodically?

That, or, it’s also possible FA has geographically-specific MLAT servers which are experiencing some kind of outage during that time. (I’m not seeing it on the other side of the pond).

I am in a poor coverage area as well and just having the number of ADS-B aircraft drop off is enough to reduce site sync with my neighbours.

I think he has enough neighbours
Feeder Type: PiAware (Debian Package Add-on) 2.1-5
Multilateration (MLAT): Supported / Enabled (synchronized with 148 nearby receivers)

Sure - but if you look at the 3 closest they all have matching MLAT dropouts today - which makes me think the problem may be outside of his specific setup.

Agreed. It looks like maybe a feeder or MLAT server had issues.
Even this user, that gets up to 900,000 position reports a day had issues

MLAT is no good without a server to collate the timing information.

looks like a lot have issues

Two of OBJ’s receivers that support MLAT also look like they had issues during this time

It is a server capacity problem. Waiting on some new hardware…

I wondered if that might be the case. I’ve noticed that the number of synchronised receivers has steadily climbed over the last few months. I used to get 90-100 most days, but up to 150 is common now.

Is there actually a large increase in receivers feeding, or is it that more existing ones have upgraded to use the mlat software?

I haven’t explicitly looked at what’s causing it but I think it is just “more receivers” more than anything.

There is a graph at flightaware.com/adsb/ that shows the growth in receivers, it’s a pretty steady growth of something like 400/month.

New hardware since today? There was a little out time and after this I get more mlat positions!

The new hardware went in yesterday (the 6th) so this should be fixed now.

It’s a bit early to say, dropout usually only started around 30 minutes ago, but all is looking well at the moment.
I note that my number of Mlat receivers has dropped to 80+ as compared to 140+ yesterday and before. Number of Mlat flights is about the same as yesterday.
Will report later in the day, thanks obj for your work to resolve this.

Yeah, this is expected. In areas with a dense population of receivers, the rebalancing process will have subdivided the mlat regions into smaller chunks to reduce the load per region (there is a limit to how many receivers a region can handle before being overloaded)

this is what the southern UK regions currently look like:

Thanks for the extra detail.
I can now confirm that there was not an outage for me today, so upgrade worked well.
Looking at todays graphs (before outage period) Mlat results were probably double yesterdays - but too small a sample to make any real judgement.
Thank you obj.