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wibbly Frequent Visitor
Joined: Dec 20, 2003 Posts: 315
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nej Frequent Visitor
Joined: Jun 16, 2004 Posts: 454 Location: London, Ingerlund
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Posted: Tue Nov 30, 2004 9:57 am Post subject: |
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16 Sats? Aren't there only 12 in each hemisphere??!
Good price though - although the $ would probably be replaced with a £ if it comes to the UK. |
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wibbly Frequent Visitor
Joined: Dec 20, 2003 Posts: 315
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Posted: Tue Nov 30, 2004 10:08 am Post subject: |
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Well it's a numbers/specmanship game too, I think. SiRF XT2 does seem to work extremely well (for me). Next gen may offer better TTF though.
20Hr battery life is also of debatable value if PDA is ~10hrs at best at the moment. But it does offer the opportunity to leave receiver on with impunity and fixed to the birds all the time, switching on PDA when you want to check position.
According to the SiRF site, SiRFstarIII chipset will achieve TTFF of 1 second and acquiring down to -159dBm, so that may be worth waiting for ;-)
J |
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lbendlin Pocket GPS Staff
Joined: 02/11/2002 22:41:59 Posts: 11878 Location: Massachusetts, USA
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Posted: Tue Nov 30, 2004 10:48 am Post subject: |
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nej wrote: | 16 Sats? Aren't there only 12 in each hemisphere??!
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Kind of. But you can theoretically see more sats becaise you are standing on top of the ball (ahm, pear). Try it yourself - draw a circle, a llittle man, and then straight lines from his eyes to the horizon and beyond. Even moe true when the little guy is in the air. or space.
Eventually it really is marketing blurb. Remember the times when you had 12 fixed sats? _________________ Lutz
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nej Frequent Visitor
Joined: Jun 16, 2004 Posts: 454 Location: London, Ingerlund
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Posted: Tue Nov 30, 2004 2:02 pm Post subject: |
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wibbly wrote: | Well it's a numbers/specmanship game too, I think. SiRF XT2 does seem to work extremely well (for me). Next gen may offer better TTF though.
20Hr battery life is also of debatable value if PDA is ~10hrs at best at the moment. But it does offer the opportunity to leave receiver on with impunity and fixed to the birds all the time, switching on PDA when you want to check position.
According to the SiRF site, SiRFstarIII chipset will achieve TTFF of 1 second and acquiring down to -159dBm, so that may be worth waiting for ;-)
J |
TTFF of 1 second? Hmmm, methinks that's not quite right.. Maybe a hot-start when you haven't moved at all, and only a few minutes have elapsed.
Beware of marketing departments! :P |
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Skippy Pocket GPS Verifier
Joined: 24/06/2003 00:22:12 Posts: 2946 Location: Escaped to the Antipodies! 36.83°S 174.75°E
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Posted: Tue Nov 30, 2004 2:51 pm Post subject: |
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nej wrote: | TTFF of 1 second? Hmmm, methinks that's not quite right.. |
That's what they are claiming for "aided starts".
http://www.sirf.com/products-ss3.html
They are pretty light on specifics but it requires a GSM phone network. There are two possibilities that I can think of:
1. They have a way of getting positioning information from the GSM base stations
2. They download almanac and ephemeris data using GPRS and load this into the receiver to "hot start" it
Anyone care to speculate? _________________ Gone fishing! |
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lbendlin Pocket GPS Staff
Joined: 02/11/2002 22:41:59 Posts: 11878 Location: Massachusetts, USA
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Posted: Wed Dec 01, 2004 3:27 am Post subject: |
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wibbly wrote: | 20Hr battery life is also of debatable value if PDA is ~10hrs at best at the moment. |
What kind of PDA do you have? Mine easily pulls 48 hrs of usage... _________________ Lutz
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wibbly Frequent Visitor
Joined: Dec 20, 2003 Posts: 315
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Posted: Wed Dec 01, 2004 9:10 am Post subject: |
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48hrs continuous use? With the backlight on? A PocketPC? That must have some big battery on it! ;-)
J |
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lbendlin Pocket GPS Staff
Joined: 02/11/2002 22:41:59 Posts: 11878 Location: Massachusetts, USA
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Posted: Wed Dec 01, 2004 2:34 pm Post subject: |
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yes, the extended battery for the iPAQ 6315 - 3600 mAh 8) _________________ Lutz
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