GLONASS Reception Failure [Bug 12]

[Wojtas81]

Montana 680t, firmware 3.50 - zero issues with GLONASS

UPDATE:

Montana 680t, firmware 3.50 - GLONASS no longer works.
eTrex 30, firmware 4.90 - GLONASS still works.

Montana 680t was released in 2015.
eTrex 30 was released in 2011.

So release date of the device doesn't matter.
Some devices are now simply unable to receive data from GLONASS satellites and nothing can be done with it.

[dont_panic]

I tested this on my GPSMAP 64 running firmware 5.30.

I can receive GLONASS on this device. After leaving the device with a clear view of the sky, it eventually shows a few tall green bars on the upper row, and I had one tall green bar on the lower row.

I'll test again and report back after I've updated to 6.60.

[Wojtas81]

It sometimes works and sometimes not. Same situation with my Montana 680t. It is pure lottery.
On the other side, other devices I have, work all the time.

Something probably has been changed in GLONASS satellite system. Some devices are invulnerable to these changes, while others (mostly those with MediaTek MT3332N GNSS chip) are not.

In theory Garmin could provide updated device software, containing updated MediaTek MT3332N firmware to address these issues.
But I doubt that they are interested.

[dont_panic]

I've just tested again with my GPSMAP 64, now on f/w 6.60: GLONASS no longer appears to be received.

The device was left in the same location with the same view of the sky for around half-an-hour. The lower row now shows no tall bars of any kind, just a row of slowly flashing orange baselines.

I'm not sure what this will mean, but when I was out on a high peak earlier today in a far less built-up area, I noticed there were more baselines visible on the bottom row, perhaps 3 or 4 more - but still no GLONASS reception bars of any kind.

I'm not sure if this supports Wojtas81's theory that the problem is down to a change with the GLONASS satellites themselves - I suppose it could be down to a little of both? Firmware definitely seems to have its part to play.

Now I have to look up how to downgrade to 5.30 again!