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Acquiring Satellites While Moving?


dhbaird

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This is in regards to a Garmin 76cs

 

I was on a route the other day and due to some telemetry problem, cloud cover or what ever I lost my satellites. I was in a heavy flow of traffic and could not stop.

 

The unit never was able to re-connect while I was moving, even after I pressed that silly prompt (press the enter button).

 

By the time I finally was able to stop, I had missed my destination and had to back track.

 

My question is... is this normal? Is there a setting (like turning off the WAAS?) that would facilitate getting the signal lock back on while moving?

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Picking up a lock while moving takes noticably longer with my GPS (A GPS V) than if I'm not moving. When you are driving around a down town area and changing the view of the sky for the GPS because of buildings and turns it can take much much longer.

 

The key is to maximize your GPS's view of the sky. It can't see through the roof of your car for example. My Front windshield also blocks signal so for my in my van I have to use a side window. Sometimes even hold the thing outside the car... Most of the time it does ok.

Edited by Renegade Knight
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As RK indicated, the problem isn't so much that you're moving as the everchanging obstructions that block various satellites which make it harder for the unit to get reception of the 3 - 4 satellites it needs for a position calculation. Using an external antenna, especially one located on the roof of your car, can help considerably when driving in urban areas with lots of tall buildings and other obstructions. The 76cs has an MCX jack for antennas like the $20 Gilsson and the cable is thin enough to run right past the door weatherstripping so it's easy to set it on the roof for best reception.

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As RK indicated, the problem isn't so much that you're moving as the everchanging obstructions that block various satellites which make it harder for the unit to get reception of the 3 - 4 satellites it needs for a position calculation. Using an external antenna, especially one located on the roof of your car, can help considerably when driving in urban areas with lots of tall buildings and other obstructions. The 76cs has an MCX jack for antennas like the $20 Gilsson and the cable is thin enough to run right past the door weatherstripping so it's easy to set it on the roof for best reception.

 

I had thought that might be the case and ordered a Gilsson the day I returned from that trip. It hasn't arrive yet.

 

I know that people say that cloud cover should not matter, but I did not lose the signal until I got under a very thick cloud cover. I did not get it back reliably until I drove out of that area and the cloud was no longer there.

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As RK indicated, the problem isn't so much that you're moving as the everchanging obstructions that block various satellites which make it harder for the unit to get reception of the 3 - 4 satellites it needs for a position calculation.

 

Moving does add in an extra factor nonetheless. Speaking as a Plains and corn state resident. There might be the occasional grain elevator but that's about it. :mad:

 

Oh, and I've got the 76cs that sits on the pulled out ashtray. It's below the dash at about armrest level for easy access and it usualy pulls in a good signal without the ext ant, but when connented to the ext, it's locked and loaded.

 

The antenna is usually magnatized so you can place it on top of your roof, but I have never had a reason to mount it that way. The dash works fine and is easier on the cable.

Edited by BlueDeuce
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I just have to say, I've rarely had a problem re-acquiring lock while moving on a bicycle - but there there's not the issue of a vehicle roof, and I've usually been riding in situations without tall obstructions. (Lock usually lost from power off, either from excessive vibration or low battery voltage in cold weather). I've only once lost lock otherwise while riding (narrow deep valley + poor satellite geometry), and even then reacquisition was fairly quick once I moved a short distance. If you lost lock because you were in a situation with poor reception to start with, by definition reacquisition will be difficult unless something changes to improve your reception.

 

Keith

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Moving does add in an extra factor nonetheless.

The effect of movement by itself seems to be very small since in airplanes I get reception about as fast when moving at hundreds of miles per hour as I do when standing still.

Speaking as a Plains and corn state resident. There might be the occasional grain elevator but that's about it.

When the receiver is getting the ephemeris data even the momentary obstruction by a utility pole can be sufficient to disrupt a bit of the data stream and make it wait for the message to repeat.

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Moving does add in an extra factor nonetheless.

The effect of movement by itself seems to be very small since in airplanes I get reception about as fast when moving at hundreds of miles per hour as I do when standing still.

Speaking as a Plains and corn state resident. There might be the occasional grain elevator but that's about it.

When the receiver is getting the ephemeris data even the momentary obstruction by a utility pole can be sufficient to disrupt a bit of the data stream and make it wait for the message to repeat.

 

Do you start the reception while already moving or have you acquired signal before the plane gets going?

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The effect of movement by itself seems to be very small since in airplanes I get reception about as fast when moving at hundreds of miles per hour as I do when standing still.

Do you start the reception while already moving or have you acquired signal before the plane gets going?

When in commercial aircraft I do so after we've reached an altitude of over 10 kft and personal electronic devices are again allowed to be turned on.

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I have a gps V and getting a lock while moving always adds to the time it takes to lock on.

It also has very much to do with the orientation of the satallites and what side of the plane your sitting on.

 

Also, I believe, that terrestrial interference is the cause of slow or no lock some times. Lots of things can impact your lock experience.

 

On the other hand, I just got my new 60csx and that thing keeps lock even inside my closed steel pole barn (with two small windows). It crazy sensative and I cant belive it..way better than my gps V.

 

The effect of movement by itself seems to be very small since in airplanes I get reception about as fast when moving at hundreds of miles per hour as I do when standing still.

Do you start the reception while already moving or have you acquired signal before the plane gets going?

When in commercial aircraft I do so after we've reached an altitude of over 10 kft and personal electronic devices are again allowed to be turned on.

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My old GPS III+ rarely has trouble aquiring a lock while moving, even on an airplane. The times that I do have trouble is when I turn on the unit after having traveled a considerable distance from where it was last powered up, then it might get lost. In that situation, it takes longer for it to sort through the almanac, figure out where the satellites are suppossed to be, and then figure out where it is. Lost signals from tunnels and such aren't a problem for it, the thing resumes very quickly.

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