LAT N/A, LONG N/A

[PiotrLem]

Hey I have a bit of a problem, I have had an ADS-B set up in my house for about 3 years now. It was working all very well, recently there was a problem with latitude and longitude. If an aircraft that my adsb catches is being tracked in M-LAT mode and after going down to a lower altitude that only my ADS-B catches it the callsign is good, altitude too, however latitude and altitude are N/A. However, if my ADS-B catches an aircraft that has been tracked in ADS-B mode from the start of my ADS-B range, everything works fine. The ADS-B itself has the latest soft, has free space on the SD card. There are no errors in the logs. Can you help?

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[slammer99uk]

Easy one to answer. MLAT requires multiple receivers to calculate position and altitude.