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Jim18655

GPSMAP 64 satellite problem

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I was going about 70 miles north from my home location and into another state so I loaded some GPX files for the area. I turned the GPS on after the meeting and it couldn't acquire satellites. I looked at the satellite page and it would get a few and then lose them. It did this several times and then it would ask if retry or use with satellites off. Retry didn't help and it would time out again. I turned it off and on - no change. I took the batteries out - no change. I removed the SD card and started over - no change. Left it on for an hour on the ride home and it didn't  connect until I was within about 30 miles from home.

I read that maybe I should have left it on for the trip so that the almanac would stay updated. Any thoughts?

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Without any battery backup or memory retention at all, it should still take only a few minutes in good conditions to get a position fix.

It’s a problem.

 

Edited by _Art_

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If this happens again try switching to GPS only instead of GPS+GLONASS. I had this problem a few times with my Oregon600 and doing this solved it.

 

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Next time this happens,  try using the AutoLocate feature:

 

Satellite Page > Menu > Use Demo Mode > Menu > AutoLocate Position > Menu > Use Satellite System

 

 

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In this situation with my 64st I have had success with the method suggested by on4bam (switching to GPS only instead of GPS+GLONASS).

 

In the past I have tried restarting the satellite acquisition using different methods (auto, manual point) without success. Getting rid of GLONASS seems to be the only solution for my 64st. It appears that something in the GLONASS process gets corrupted and it takes a few hours to get corrected. I usually leave GLONASS off until the next day. On my unit GLONASS corruption appears infrequently, perhaps something less than 1% of the time. It seems to appear upon initial power-up. I don't think I have ever seen the unit go from working in GPS+GLONASS to not working while continuously powered. It has occurred when powering up after only seconds of off time and hours or days of off time. It could be that something gets corrupted in the power cycle.

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First time I had this happen was on a long weekend away from home. We took our bikes and left the hotel underground parking. We were well underway and there was no sat lock so we stopped and after a few minutes the GPS had a location. We got back on our bikes and a few 10's of meters I had "lost satellite lock" again. After a few tries and restarts I disabled GLONASS and immediately had a position lock. No more problems for the rest of the day and the next day with GLONASS enabled we had no more problems.

It happened a few times since but is fixed in seconds now. It looks like waiting a few hours before re-enabling is best. Most of the time precision is the same anyway.

 

 

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48 minutes ago, on4bam said:

First time I had this happen was on a long weekend away from home. We took our bikes and left the hotel underground parking. We were well underway and there was no sat lock so we stopped and after a few minutes the GPS had a location. We got back on our bikes and a few 10's of meters I had "lost satellite lock" again. After a few tries and restarts I disabled GLONASS and immediately had a position lock. No more problems for the rest of the day and the next day with GLONASS enabled we had no more problems.

It happened a few times since but is fixed in seconds now. It looks like waiting a few hours before re-enabling is best. Most of the time precision is the same anyway.

 

 

 

My studies thus far suggest to me GLONASS is no real advantage unless you are under deep cover or in an otherwise largely obstructed satellite viewing position. If GPS only is working for your location, I suggest not using GLONASS.

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Thanks for the replies and suggestions.

I diddn't think about turning off GLONASS.

It was frustrating because I needed a cache for the calendar day. Luckily, my friend's phone was working OK to find the cache we went looking for.

How much effect would a very overcast day have on reception? His phone GPS worked so I would think the GPSMAP would work better.

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Overcast skies have no quantifiable affect on your GPSr ability to receive satellite signals.

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