MLAT Anomalies

FlightAware ADS-B Flight Tracking
61

I’ve just put the older 4.4 kernel packages in the FlightAware apt repository. If you have this configured (piaware sdcards have this by default) then you can prevent upgrades past 4.4 by creating a file /etc/apt/preferences.d/50-pin-kernel.pref containing this:



Package: raspberrypi-kernel raspberrypi-bootloader libraspberrypi0 libraspberrypi-bin
Pin: origin "flightaware.com"
Pin-Priority: 995

You can check it’s correct via apt-cache policy:



$ sudo apt-get update
$ apt-cache policy raspberrypi-kernel
raspberrypi-kernel:
  Installed: 1.20170405-1
  Candidate: 1.20170405-1
  Package pin: 1.20170405-1
  Version table:
     1.20170703-1 995
        500 http://archive.raspberrypi.org/debian/ jessie/main armhf Packages
 *** 1.20170405-1 995
        500 http://flightaware.com/adsb/piaware/files/packages/ jessie/piaware armhf Packages
        100 /var/lib/dpkg/status

This is probably what I’ll do for the next piaware sdcard release.

62

I am having the issue with mlat suddenly not working. I recently moved to a Raspberry Pi 3 and hoped that would solve the problem, but it didn’t. I’ve found that if I change the setting for the antenna height and reboot, all is well for a while. So, I’ve been alternating between 9 feet and 10 feet each time I see the anomaly warning that mlat has stopped. I don’t have other software running on my Pi.
Ken

63

It sounds there are a couple things you can eliminate. 1. The kernel issue is only with the older models, so it won’t be your issue. 2. The MLAT calculations are not sensitive enough for 1 ft to cause a difference. I suspect every time you’re doing that, it’s simply resetting and giving your receiver another chance. It’s not really fixing the underlying problem. Are you using anything in-between the Pi and the USB dongle? Does the red LED stay solid red?

64

I’ve got a single USB 3 extension cord from Amazon that I use between the Pi and the dongle. It’s the extension cord that’s listed on the Piaware required/recommended equipment page. The red LED is on all the time as far as I know.

65

May be a coincidence, but seems that MLAT is much more stable with 4.9.43 kerenel (the latest from rpi-update).

66

Good news and bad news!

The good news is that the latest kernel available via rpi-update (4.9.46 at the time of posting) does indeed seem to work better. I’ve been running it on a Pi 2 for 45 mins with no timestamp jumps. 4.9.35 on the same hardware would usually break within 15 minutes.

46
46800×600 5 KB

The bad news is that 4.9.35 is still the most recent packaged kernel, so the piaware sdcard image will need to stick with the old 4.4 kernel for now until a more recent version is packaged.

1 Like
67

Upgrade to kernel 4.9.50 on raspbery 2 and working fine now…

Linux adsb 4.9.50-v7+ #1035 SMP Wed Sep 13 23:16:24 BST 2017 armv7l GNU/Linux
1 Like
68

Thanks for this its been doing my head in for weeks… I was on 4.9.35 and rebooting mlat would work for 10 to 15 minutes then come up with the timing errors. All the posts said it was location wrong or not enough receivers. I ran sudo apt-get install rpi-update then sudo rpi-update followed by a reboot and mlat has been fine since. Im now on 4.9.79