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lydiachris
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Joined: Mar 09, 2005
Posts: 193
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 Posted: Tue Nov 07, 2006 6:36 pm Post subject: GPS Screen |
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Hi people,
Just a quick question, I regualary use a go 910 and tomtom one gb. I'm sure many of you lot do as well, i often go into the GPS screen, just to check how many/what sattelites i'm picking up.
Do any of you know what all the numbers mean on the blue bars, I think they might be the number of the sattelite that your receiving from, but why are there 2 numbers on each bar?!
Also I don't get the round circle with all the blue dots in, I think they might be where the satellites are around the earth, but can someone explain to me exactly who this works, is the top of the circle, north? If so, is my TomTom the center of the circle?!?!?  
Sorry to confuse you all!
lydiachris |
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Oldboy
Pocket GPS Moderator
Joined: Dec 08, 2004
Posts: 10642
Location: Suffolk, UK
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| Posted: Tue Nov 07, 2006 8:54 pm Post subject: Re: GPS Screen |
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| lydiachris wrote: | | Do any of you know what all the numbers mean on the blue bars, I think they might be the number of the sattelite that your receiving from, but why are there 2 numbers on each bar?! |
The second number is the Signal-to-Noise Ratio. The larger the number the better. I believe anything over 43 is good.
| lydiachris wrote: | | Also I don't get the round circle with all the blue dots in, I think they might be where the satellites are around the earth, but can someone explain to me exactly who this works, is the top of the circle, north? If so, is my TomTom the center of the circle? |
Yes and yes.
TT can work out the relationship of all the satellites in relation to your current, or last, position.
It's just a graphical representation of their position.
If you have a little time to spare, you can watch the screen for a while and you'll notice them shifting about. Shifty lot these satellites.;)
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Richard
TT 910 V7.903: Europe Map v1045
TT Via 135 App 12.075: Europe Map v1120 |
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lydiachris
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Joined: Mar 09, 2005
Posts: 193
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| Posted: Tue Nov 07, 2006 11:22 pm Post subject: |
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Thanks for letting us know about that Richard.
Always wondered what all the numbers meant, it's just it isn't stated anywhere in any of the tomtom manuals, so where do tomtom expect you to find all this out?!
Perhaps tomtom should commision you guys at pocketgpsworld.com to be there tech support
Not being thick, but what does signal to noise actually mean referring to sattelite signals?! |
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Border_Collie
Pocket GPS Verifier
Joined: Feb 01, 2006
Posts: 2543
Location: Rainham, Kent. England.
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| Posted: Wed Nov 08, 2006 1:07 am Post subject: |
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Signal-to-noise ratio is an engineering term for the power ratio between a signal (meaningful information) and the background noise:
Because many signals have a very wide dynamic range, SNRs are usually expressed in terms of the logarithmic decibel scale. In decibels, the SNR is 20 times the base-10 logarithm of the amplitude ratio, or 10 times the logarithm of the power ratio:
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Formerly known as Lost_Property
And NO that's NOT me in the Avatar. |
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tgold
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Posts: 98
Location: UK or USA from time to time.
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| Posted: Wed Nov 08, 2006 1:43 am Post subject: |
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| Lost_Property wrote: | | Signal-to-noise ratio is an engineering term for the power ratio between a signal (meaningful information) and the background noise: |
Close, but it's actually the ratio between the signal plus the noise and the noise alone.
Tony |
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Border_Collie
Pocket GPS Verifier
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Location: Rainham, Kent. England.
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Oldboy
Pocket GPS Moderator
Joined: Dec 08, 2004
Posts: 10642
Location: Suffolk, UK
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| Posted: Wed Nov 08, 2006 8:26 am Post subject: |
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So there you have it.;)
In other word; the bigger the number, the 'cleaner' the signal, the better the reception.
_________________
Richard
TT 910 V7.903: Europe Map v1045
TT Via 135 App 12.075: Europe Map v1120 |
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Eldar
Pocket GPS Moderator
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Joined: Sep 24, 2004
Posts: 1294
Location: London
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| Posted: Wed Nov 08, 2006 11:53 am Post subject: Re: GPS Screen |
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| Oldboy wrote: | | lydiachris wrote: | | Do any of you know what all the numbers mean on the blue bars, I think they might be the number of the sattelite that your receiving from, but why are there 2 numbers on each bar?! |
The second number is the Signal-to-Noise Ratio. The larger the number the better. I believe anything over 43 is good. |
Anything over 39 for one of the sats and at least 2 other over 37 is decent; 40-41 is good, anything over 41 is perfect if assisted satellite navigation (aka quickfix) is off. |
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Eldar
Pocket GPS Moderator
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Joined: Sep 24, 2004
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Location: London
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| Posted: Wed Nov 08, 2006 12:01 pm Post subject: |
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| Oldboy wrote: | So there you have it.;)
In other word; the bigger the number, the 'cleaner' the signal, the better the reception. |
But then you also have DOP of course :-) |
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