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MajorMajor

Satellite Signal Strength: Is There A Difference Between Am And Pm?

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Sorry for the double post but forgot to check off email notification.

 

Out of curiosity, is there any correlation to having a poor signal in the mornings compared to the afternoons with Satellite positioning?

 

The problem I am encountering is that while riding with my GPS mounted to my handlebars in the morning I will more than likely drop signal. Whereas, if I ride the same course in the afternoon I never lose signal.

 

Any thoughts why that might be? Where I am riding has heavy tree cover.

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Satellite configuration is the most likely cause. The satellites move in orbits of almost 12 hours. Where they are has a direct impact on signal strength.

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http://trimble.com/planningsoftware_ts.asp

 

ftp://ftp.trimble.com/pub/eph/almanac.alm

 

Try the Trimble Planning program above (free) It will help you understand what is going on, not just morning vs afternoon, but day to day, location to location. Best conditions are when you see the combination of numer of Sats are at least greater than 5 and PDOP is Low(est). Show both graphs (Sat # & PDOP) and tile horizontally.

 

Get the latest almanac from the second site above, instead of using the "Current Ephemeris" file on the first site because I have found that the Ephemeris file is sometimes not up to date.

 

You can set up a "station" as your house with the known coordinates, or any where else that you know the coordinates of and want to know the GPS satellite viewing conditions, or when your GPS readings might be best (or worse)

 

Look at some of the reports etc and you will be able to see what sats (actual individual sat ID #) should be available at what times, and if you go outside with your GPSr at that time .....voila!, that's the Sats it can see!

And you could tell all that information even before you went outside to try it!

 

Excellent program for understanding why you see what you see on your GPSr, and that some of the "Unexplainable" is actually "to be expected".

 

Try it, play with it, change things, see what's available, screw up, beat your head on the wall, start over....that's the Brute Force method of learning, sometimes slower, sometimes faster, but you will always "retain" more. ....because you've learned what "not to do" along with what "TO DO".

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