Subject: [SIR-Mail] No.923: GLONASS tracking problems due to illegal ephemeris transmission.
From: Wernher Ibanez Leon

Dear Sirs,
 
Since April 1s,t from about 20:30 / 08:30pm UTC onwards GNSS receivers experience tracking problems with GLONASS satellites.   

The GLONASS service web site indicates that illegal ephemeris is being transmitted.  Please refer to the main web site at:   http://glonass-iac.ru/en/GLONASS/DayMonitoringNew.php

Clicking the top left plot indicates that ”illegal” ephemeris have been detected. 


 So far, the symptom observed on different receivers is poor GLONASS measurement quality or missing GLONASS observations. 
 
About this problem since about 06:00am UTC, for most satellites valid ephemeris have been broadcast and receivers do automatically recover normal tracking behaviour. I will continue to observe the situation and tracking behaviour of our receivers. Should additional actions be required to recover we will keep you informed.
 
Best regards,
 
Wernher Ibanez L.
Technical Support for Hardware Receiver