GLONASS Reception Failure [Bug 11]

[Wojtas81]

It is no longer possible to receive position from GLONASS satellites on Garmin Montana 610/680.

My case:

Garmin Montana 680t, firmware version: 3.50

I have removed the content of /Garmin/GPS folder and triggered AutoLocate function to force clean satellite reception.

Results:

Montana 680t GPS+GLONASS satellite page

Montana_680t_No_GLONASS.bmp

Montana 680t GPS only satellite page

Montana_680t_GPS_only.bmp

The bug is identical to these cases:

• GPSMAP 64/64s/64st GLONASS Reception Failure
• eTrex Touch 25/35 GLONASS Reception Failure
• Oregon 600/650 GLONASS Reception Failure

[Wojtas81]

I have managed to fix it.

What I have done:

1. I have switched to GPS only mode.
2. I connected Montana to my PC and removed the content of /Garmin/GPS folder.
3. I triggered AutoLocate function and went outside.
4. I acquired GPS fix.
5. I switched from GPS only mode to GPS + GLONASS mode.
6. GLONASS satellites were found after a while and seem to be working again.

Results:

Montana 680t GPS+GLONASS satellite page

Montana680t_GLONASS_Working.bmp

Maybe it will help somebody.

[Wojtas81]

Unfortunately, GLONASS is malfunctioning again. Satellites are either pale or are blinking indefinitely.
This time solution from my second post hasn't fixed anything.
It looks it just depends on time od day.

Hardware failure is unlikely, because the device is bought as new and rarely used since I bough it.
Two months ago or so, everything worked flawlessly.
All these GLONASS issues started recently.
GPS + WAAS/EGNOS (ie. "D" letters on satellite bars) are working without issues all the time.

Probably without GNSS firmware update, GLONASS malfunctioning cannot be fixed. Same situation as with other devices where GLONASS stopped working suddenly.

[gs2offroad]

Same with Montana 610t firmware v3.50.
No GLONASS reception.

[GPSrChive]

Turns out the Montana 610/680 use the same GNSS chipset (MediaTek MT3332N) as the eTrex Touch 25/35, Oregon 6x0/7x0, GPSMAP 64 (non 'x') and Rino 75x, most of which have reports about similar issues!

[Wojtas81]

There are some differences:

1. GPSMAP 64 (non 'x'), Montana 610/680, Oregon 600/650 etc. use HotFix* satellite prediction.
   Oregon 700/750 use EPO.BIN instead.
2. Oregon 700/750 location accuracy is noticeably better than Oregon 600/650 or Montana 610/680.
3. Oregon 700/750 have still working GLONASS reception.

Something was modernized in Oregon 700/750 when comparing them to previous devices.

HotFix satellite prediction technology is a feature available on automotive devices to decrease satellite acquisition time dramatically. By using data collected over the period of a few days of regular use, the device will predict the position of the satellites for up to 3 days. If the GPS device has not been used for a few days it will acquire the satellites normally. (Source: Garmin Support)