Has anyone been able to solve the issue with MLAT timing issues? I have read through the forums and nothing has resolved my issue. I have done the below and still seeing these timeout issues.
I have and had the same issue. Timeout penalty starts at 0s and slowly grows until about a 900s timeout. I have read that it could be that packet are being lost between the antenna and the Pi but I have not found a way to test that out.
I have one Radarbox dongle and that needed a PPM offset in order to behave nicely for the timing being incorrect.
I added that as an option to the dump1090-fa config file.
Sudo nano /etc/default/dump1090-fa
Add the following line to the extra options section:
Additional options can be added here:
EXTRA_OPTIONS=“–ppm +65”
The PPM value can differ, you will have to check if there is an offset in the ADSBexchange stats that seems to be common to multiple connected stations.
This cured the issue for me with the Radarbox dongle, for other dongles (RTL-SDR v3 and Flgihtaware Prostick Plus) I didn’t need to set this value.
I guess the radarbox dongle has a cheap non-tcxo crystal if it’s 65ppm out. The Prostick and – I think – the rtlsdr v3 both have TCXOs which should be good to within 1ppm or so.
(mlat will generally tolerate up to around 100ppm total error between pairs of receivers, so if you’re 65ppm out just from local error then that’s going to be borderline if paired with another receiver that also has a large error)
I agree with you on the quality of the Radarbox dongle. I have it for testing purposes, bought it secondhand and performance wise it is the least performing dongle that I own.
Thanks for the PPM offset idea, the container has a script to estimate the recommended offset which is currently running. Adding to my theory of lost packets, this is in the script output. What would be causing that loss?
The issue is in the dongle hardware as explained by @obj . You can compensate some by setting the ppm offset but that’s about it. Not much else you can co about it. Based on the output of your script I’d set a ppm offset of +13 in the dump1090-fa config file and check if it gets better. If not then you might want to consider if you want to use a different dongle. As said, I have it for testing purposes so that one doesn’t need replacement.
That makes sense and that is what I have heard from others regarding RadarBox hardware. Last night I ordered FA Pro Stick Plus, coax, and 1090 MHz Antenna with plans to returns my current hardware to Amazon as its literally a week old.
Added the PPM Offset and my time has come down. Will continue to play around with that setting until the new hardware gets here
Thanks.
I’ve just been through the same process with an AIS receiver. The offset with that is opposite sign to bring the error to zero https://www.sarcnet.org/ais-receiver.html
The crystal is clear enough, but unfortunately no part number to identify it (XO, TCXO etc.)
If you felt really keen, you could tweak C6, C7 to pull it onto correct freq.
I have one like that which I never used (never unboxed). I purchased it in sale by AirNav Radarbox I think 2 or 3 years ago when they sold every dongle for $9.50 and free shipping. At that time I purchased following:
2 x Green Dongles (1090)
1 x Red Dongle (978 MHz)
1 x Blue Filter (1090 MHz)
1 x Black Dongle (micro)
I also have NooElec Black Dongle since 2013,. Never had any issue of MLAT when used on RPi. However I normally use the NooElec black dongle with x86_64 OS installed in Virtual Machine on Windows, and most of time get MLAT clock out / Synchronization issue. However this is not due to dongle itself, it is due to bad pass-through of dongle from Windows to VM.
CLICK ON IMAGE TO SEE LARGER SIZE CLICK AGAIN TO SEE FULL SIZE (1920 X 2560 PX)
Yep that’s the one, I bought it 2nd hand with the antenna included for 15 euro. I cut the antenna to 69 mm in order to improve the reception.
I suspect that the Nooelec and the Airnav model are identical in hardware layout and that just the stamp on the plastic is different.
I use it for testing out a location for a week or 2 when setting up a new antenna and then put in a RTL-SDR or. Prostick Plus when I put it in operation.
Purchase some jewelry for Her Majesty, and after giving it to her, tell her you are going to install 11th station. Sure you will be granted instant permission.
Funny that the conversation turned to RadarBox gear and AIS …
A couple of weeks ago I pulled my first ADS-B antenna out of a drawer to see if I could extract some value from it instead of it just collecting dust. It is a RadarBox branded mag-mount whip, specifications completely unknown, except for “1090 MHZ” on the packaging. I connected it to a RTL-SDR Blog v3 to see if I could pull in AIS. I had very low expectations, not just of the antenna but also my location being 6 meters above ground in an upstairs bedroom and multi-story buildings on three sides of me.
The end result was much better than I expected - 50-70 vessels tracked at any given time during the peak daylight hours and 20nm range in some directions. Considering the cost to me was nil (antenna, dongle and thin client computer already in hand) I have no complaints at all with what I am getting. My advice is you never know until you give it a try.
P.S. There are several AIS decoders out there but I have had great success and been impressed with AIS-catcher
the last figure is the number suggested.
