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Darren
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Joined: 11/07/2002 14:36:40
Posts: 23848
Location: Hampshire, UK
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 Posted: Fri Jun 27, 2008 2:27 pm Post subject: |
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| kichu1979 wrote: | To understand what GPSfix is all about you would need to understand how GPS calculates your postition. For the initial position calculation your GPS chipset needs to find at least 4 satellites with strong enough signal (28 dbHZ or more) and keep those satellites and the signal strength for about a minute to download data from the satellites that is essential for calculating your position (called ephemeris).
SNIP
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Would you mind if I incorporated this into the 'How GPS Works' article?
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Darren Griffin |
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kichu1979
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Joined: Jan 29, 2008
Posts: 99
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| Posted: Sat Jun 28, 2008 12:09 pm Post subject: |
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Go ahead, my pleasure  |
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Darren
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Location: Hampshire, UK
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| Posted: Sat Jun 28, 2008 12:26 pm Post subject: |
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Excellent, now incorporated, thank you.
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Darren Griffin |
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kichu1979
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Joined: Jan 29, 2008
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| Posted: Sat Jun 28, 2008 1:37 pm Post subject: |
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| Could you please post the link to the article. Thanks. |
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Trevor1234
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Joined: Apr 30, 2005
Posts: 810
Location: Milton Keynes
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| Posted: Sat Jun 28, 2008 1:44 pm Post subject: |
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| mikealder wrote: | | Instead of getting a Davy lamp out and going down the nearest mine try this: |
Hi Mike
Yes, I have used the method that you have suggested and it works, but only on Advanced Planning. Start point to Finish point only. But I am talking about Itinerary Planning with numerous way points.
Example. If your present location is Milton Keynes and you have just planned an Itinerary from Montpellier to Paris and then go to Details, Route Demo (or Browse Map Of Route) it will always start from your present location (MK). It will do this because the Device has a GPS fix. I know that this problem isn’t the end of the world but it used to be frustrating when I wished to view the route to check that all was well. However, time moves on and I now use the Tyre/Google Maps method to plan the Itinerary and that works a treat.
Edit Once to resolve quote incorrectly posted - mikealder
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Trevor1234
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Posts: 810
Location: Milton Keynes
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| Posted: Sat Jun 28, 2008 1:52 pm Post subject: |
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Sorry Folks
I made a right cock-up with the last Post. It wont happen again.
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Andy_P
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Joined: Jun 04, 2005
Posts: 19991
Location: West and Southwest London
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| Posted: Sat Jun 28, 2008 2:05 pm Post subject: |
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I wasn't going to bother to mention it, but if it is going to be kept for posterity, can you just double check the term "dbHZ" kichu?
The Decibel (abbreviated dB - small d big B) is a measure of the relative difference between two levels, voltages, signal strengths, etc.
It often has another letter or two after the dB to specify what it is referenced to, but I have never seen it used with "Hz" which is a measure of [u}frequency[/u] |
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Oldboy
Pocket GPS Moderator
Joined: Dec 08, 2004
Posts: 10642
Location: Suffolk, UK
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| Posted: Sat Jun 28, 2008 2:44 pm Post subject: |
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For a little light reading, try This, Andy. 
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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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Trevor1234
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Joined: Apr 30, 2005
Posts: 810
Location: Milton Keynes
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| Posted: Sat Jun 28, 2008 3:01 pm Post subject: |
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Hell Oldboy
If that’s your idea of light reading I sure wouldn’t want to get tangled up in your heavy stuff.
I’m sure that Einstein would have backed away from that article and gone back to his theories.
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Darren
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Andy_P
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Joined: Jun 04, 2005
Posts: 19991
Location: West and Southwest London
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| Posted: Sat Jun 28, 2008 3:53 pm Post subject: |
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Okey Doke.. I learnt something today.
There seems to be a new trend for describing signal to noise ratio in dBHz.
Even Nasa have been struggling to keep up:
| Quote: |
All:
Below is a portion of an email that was sent out to the teqc mailing
list earlier today. Angie Moore suggested that I forward on the
portion concerning SNR to the igsmail list.
SNR:
Several formats (e.g. Leica LB2 & MDB, Javad JPS, Topcon TPS, CMC
Allstar binary) have been using SNR in dBHz for some time.
Two manufacturers, Ashtech and Trimble, have introduced receivers
which now store SNR in dBHz...... |
So, the only correction needed for us anoraks would be the capitalisation to "dBHz"  |
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