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Fog messing up satellite lock?


v2lek

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Hi,

 

played around with my 60CSX a bit, so that it is now in autolocate mode, thinks that time is 00:00 etc, but did not make master reset.

 

Anyway, long story short - it now is locating satellites, I left it at window for a 30 minutes - no luck. tried to stand with it on balkony for some time - no luck there either. So I am a little bit worried.

 

Weather is quite foggy:

 

fog.jpg

 

I'ts actually a little bit more foggier than it seems to be on this picture.

 

So I wonder is this normal with such weather or did I foo-bared my unit up :unsure:

(just cant wait the fog to clear up so I have to ask here :unsure:)

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"GPS provides accurate location and time information for an unlimited number of people in all weather, day and night, anywhere in the world."

 

So they say, yes.

 

howerer this should be cold start or the initial fix on satellites - right now the gps dont know whats up there, where it is itself or what time it is. If the signal is weak or erratic due do weather conditions, it might be in trouble for initial fix. Or so I at least hope ..

 

Oh well, I quess I'll see soon enough. if not before then tomorrow for sure :unsure:

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Your fix is based on receiving satellite signals from space and is calculated based on the speed of light in a vacuum. Of course there is an atmosphere on Earth so there is a base correction for this. When weather conditions change this changes that basic correction and this does affect your position fix, but you should still receive the signals. WAAS uses geostationary satellites connected to ground stations to track weather patterns and transmit GPS corrections assiciated with said weather. That is why WAAS station corrections are only good for around 200 miles of the ground station. If you are forther than that from a WAAS ground station and have enabled WAAS you could be getting erroneous "corrections"...that are actually inducing error into your fix. Don't enable it unless you know where the nearest WAAS station is.

 

That said, I have noticed that pine forests kill satellite reception worse than any other environment.

The concrete jungle of a city with tall buildings kills satellite reception too.

My older GPSs had a hard time getting reception in vehicles unless they were near a window or I hooked up my external gps receiver/antenna. Not the case with my new ones with good antennae.

Sometimes dense rain/fog can put a damper on GPS performance.

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Your fix is based on receiving satellite signals from space and is calculated based on the speed of light in a vacuum. Of course there is an atmosphere on Earth so there is a base correction for this. When weather conditions change this changes that basic correction and this does affect your position fix, but you should still receive the signals. WAAS uses geostationary satellites connected to ground stations to track weather patterns and transmit GPS corrections assiciated with said weather. That is why WAAS station corrections are only good for around 200 miles of the ground station. If you are forther than that from a WAAS ground station and have enabled WAAS you could be getting erroneous "corrections"...that are actually inducing error into your fix. Don't enable it unless you know where the nearest WAAS station is.

 

That said, I have noticed that pine forests kill satellite reception worse than any other environment.

The concrete jungle of a city with tall buildings kills satellite reception too.

My older GPSs had a hard time getting reception in vehicles unless they were near a window or I hooked up my external gps receiver/antenna. Not the case with my new ones with good antennae.

Sometimes dense rain/fog can put a damper on GPS performance.

Baloney! Sorry to be harsh but you don't know what your talking about.

Fog does not affect the GPS signal. Weather is not a factor. Distance from a ground station is not a factor with WAAS. WAAS does not track weather. It tracks Space weather. The Ionosphere. An active ionosphere can slow a signal and cause an inaccurate position, but the GPS signal is a frequency that was chosen because it is largely unaffected by terrestrial weather. Your idea that distance from ground stations holds true with DGPS ground transmitted corrections, but not for the WAAS system which builds a model of corrections and uses your GPS's position to implement those corrections. As long as you are within the WAAS correction area (basically all of North America) you will get equal benefit from the system and be able to apply the needed corrections for your position.

 

Most likely you are having some trouble getting an intial lock because you are near too many building. Get out in an open field and turn it on and let it aquire for maybe 30 mins and you should be good to go from there next time you fire it up. Be patient the first time.

 

WAAS realtime correction area http://www.nstb.tc.faa.gov/RT_VerticalProtectionLevel.htm

Does weather affect GPS: http://www.gpsinformation.net/gpsclouds.htm

 

"WAAS improves accuracy by correcting for errors in the satellite's clock and orbit, and for ionospheric (upper atmosphere) errors." One nano-second (one billionth of a second) of error equals one foot of position error. What WAAS does is collect data at stations, which sends this data to a master station which uses this data to make a universal model of corrections, a net of corrections, send this data to the WAAS sats which sends these corrections to your GPS, which figures out where it is in the net of corrections and uses the nearest data to correct your time and position. The position of the stations at this point are irrelavant.

Edited by EraSeek
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Thank you all for answers.

 

I did go out yesterday evening to find a place with better weather. Visibility was, well, allmost nonexistant. Kept the GPSr on dashboard, under the windscreen the whole time. Well, no luck. Parked the car, did the master reset on GPSr and put it on the roof of the car in a open area for 10 minutes - no luck there either and the weather was still so bad that you could walk over a cliff without realising it before its too late :lol:.

So, anyway, still no luck.

Lefti it on my desk for night on external power - in a place where it usually picked up satellites relitevely fast and when I took it out of the box after receiving it - it did get its initial lock there without any problems within a 1-2 minutes or so. Still - no luck as todays morning, it was still showing "Locating satellites" and blank screen, without a single bird in the view. No bars, no satellites, only empty screen. Looks like everything is working as it should but "the antenna is just not there". *Sigh*. So now I left it on the window for the time I'm @ work. Probably its still dead in the water when I get home, but worth a try anyway.

 

I've been googling around and found few having kind same problem. malsington maps thread about similar problem

So I will try this solution, reuploading the firmware. After work, probably will go to some open area and leave it there on for a 30+ minutes. Dont know if it has the all symptoms (corrupted firmware) as in above thread but will try it anyway.

If that doesnt work then I'm quessing I have to take it to the next level and speak with garmin tech support, hoping that they come up with something.

 

Oh, and when I point it out on the map where I am, it goes from "locating satellites" to "acquiering satellites". But still with no luck. The screen is still empty, with nothing but N E S W on it. Time and date of the unit is now terribly off (about 4 days, after master reset, before it was like few hours off, I think.). So this could be a problem also. Alltough, in autolocating mode, as I understand, it makes no assumptions about the place or time, it just brute forces.

 

Most likely you are having some trouble getting an intial lock because you are near too many building. Get out in an open field and turn it on and let it aquire for maybe 30 mins and you should be good to go from there next time you fire it up. Be patient the first time.

 

As stated above, it did get first initial lock in the building with no problems. But as also stated above, I wil ltry this out today after work...

 

Thank you all again for your answers. I'll give update if there is any news.

 

Sorry for the long whine. I'm a bit worried :D

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And another thing,

 

when I boot it to diagnostic mode (power + enter, while powering up)

 

it shows among other things:

 

Frequency 16369000

Signal: -----

C/NO: -1.00

 

So, it seems that its not receiving ANY signal at all. or at least thinks that its not...

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Hi

 

A quick call to +44-870-8501242 (Garmin Europe support number) will have you up and running pretty quickly.

 

Actually, it I have to hand it to you.. it worked!

 

I linked before to the thread where gps sw version was set to 0.00.

 

I reflashed the software, but not GPS SW.. assuming for some reason that it was it. Well. it wasnt. So, helpful garmin worker asked me the what are the versions.. I previously was cheking version from diagnostics screen, that showed only software version but not GPS SW, otherwise I might have figured it out myself. I do feel bit stupid now :rolleyes:

Anyway, long story short. reflashed GPS sw to be version 2.90 and it started to pick up satellites immediatly :)

 

woohoo :)

 

Thanks to all for all the help :)

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