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[GUIDE] - "A-GPS (Assisted GPS, GNSS, and SBAS)" Book by F. van Diggelen
Posté le 18 mai 2010 à 16:34:00 par gpspassion. EN - technique
Source : Gpspassion

Updated May 18th, 2010
I recently purchased the A-GPS (Assisted GPS, GNSS, and SBAS) book on Amazon. This book was written by Frank Van Diggelen whom I'd met in early 2006 in San Jose when he was with Globallocate. Globallocate was bought by Broadcom in 2007 and their GPS technology is now in widespread use : iPhone 3G and 3Gs, iPad 3G, all current TomTom GPS systems, etc...

The book goes into a lot of technical details, but remains readable by "non-engineers". Having started reading the book I can confirm this. Will now be digging in deeper and will be happy to share notes with other readers in the [BOOK] A-GPS (Assisted GPS, GNS, and SBAS) topic of the "GPS and Mobile News" forums.

Updated Februray 8th, 2008 - Most of the time in high-tech, months separate announcements from actual availability to the end user, but not so with SiRFInstantFixII (SIFII) that is already available on the Garmin nüvi 7x0 AIOs, courtesy of the v2.60 software and "silent" GPS firmware updates. The arrival of SIFII is certainly a welcome addition on the 7x0 AIOs as their ultra-slim design with a patch antenna facing the road is not very "GPS efficient"...

... and it resulted in slow starts in the morning compared with the competition. Based on early testing, the improvement is quite dramatic, with TTFF down from 2+ minutes to less than 10 seconds ! More details in this topic of the nüvi forums.

Updated January 2nd, 2008 - SiRF have just announced SiRFInstantFixII for faster GPS acquisition. Compared to SiRFInstantFix v1 (SIF v1) launched in early 2006 and used very effectively on the TomTom GO systems...

..., as seen in this comparison, and the Mio and Eten GPS PDAPhones, the predicted ephemeris data is no longer downloaded over the internet but generated directly by the GPS system for full autonomous use. This is of course reminiscent of the "Autonomy" technology by Centrality (they were bought by SiRF in June 2007, see news) and released for the first time on the HP iPaq 310 with good results.

While this new version of SiRFInstantFix seems perfect on paper, there may be some drawbacks compared to SIF v1 depending on how it is implemented. You can use this thread of the news forums to discuss.

Updated March 21st, 2007 - After Globallocate's "LTO", SiRF's "SiRFinstantFix" and u-Blox's "AssistNow offline", another GPS chipset designer has announced the availability of an "offline A-GPS" service to speed up the first fix in the morning. NemeriX were demonstrating NeX at the 3GSM show in Barcelona and even inside the hall a warm fix was possible, consistent with the -155dBm rating. As for the 21 day "autonomy", we'll have to wait for the first NeX equipped GPS systems to become available to verify it. In the meantime, you can use the "Offlne A-GPS" topic to discuss. In other A-GPS news, if you own a Mio or Eten GPS PDAPhone, be sure to check out the latest version of SiRFdemo PPC that gives some interesting insight on how "offline A-GPS" works......

Updated January 16th, 2007 - Nearly a year after SiRF, uBlox are also launching their "AGPS over the internet" solution, called AssistNow® Offline. In the same way as Globallocate's LTO and SIRF's SiRFinstantFix, the idea is to predict the orbit of the GPS satellites to speed up the time to first fix in the morning and in difficult environments (urban canyon, coated windshield, indoors, etc...). They're going one step further though with a lifespan of 14 days versus 10 for Globallocate and 7 for SiRF...... and there will be a free version and a premium version. uBlox chipsets are not currently used on consumer GPS systems, but their SuperSense enabled Antaris 4 will power Navigon's upcoming Porsche Design 9611 AIO. More details in the "AGPS over Internet" thread in the forums.

Updated June 23rd, 2006 - The wait will have been shorter than expected as Eten has just made two ROM upgrades available to bring SIF to the G500, a new ROM for the PDA and a new ROM/firmware for the SiRFstarIII module that goes from v3.1 to v3.2...... Thanks to epicurean for sharing the good news in the G500 Topic. Still working on the upgrade myself, but feel free to share you findings.

Updated 06/14 - SIF (SiRFInstantFix) that works wonders on the Mio A701 as Globallocate's LTO does on the HP hw6515 to speed up the "FIX" will also become available on the Eten G500 via a ROM upgrade during the summer. At the 3GSM show, Fujitsu also mentioned SIF for the Loox T830 announced for this summer as well. On the other hand, still showing it as being "available soon" although the GO x10 series have been available for a couple of months now. You can use this thread to discuss.

Updated 03/10 - At the end of January, SiRF announced SiRFInstantFix (IF), an AGPS over the internet solution to speed up the first time to fix and in some cases make it possible, like Globallocate's does on the HP hw6515. We now have some more information about it: There is no planned upgrade path for existing SiRFstarIII based systems, First PDAPhone with IF: Mio A701 with "Quick Position", First AIO with IF: TomTom 510/710 and 910, with "QuickLocate". More details and screen captures in this thread of the forums.

Updated 02/08 - Activity is clearly ramping up in the field of A-GPS over the internet with the recent announcement by u-Blox of their own solution......After Globallocate's LTO implemented on the HP hw6515 (see the full review), SiRF's announcement of SiRFInstantFix (see below), this is the third A-GPS via the internet solution that relies on the prediction of ephemeris data to make the initial "fix" nearly instantaneous. This makes sense as live ephemeris downloading has now become the most time-consuming element (30 seconds) with powerful chipsets that can compute a fix very quickly once that hurdle has been overcome......You can use this thread of the "GPS and Mobile News" forums to discuss....

Posted 01/26 - Hot off the wire, SiRF (website) have just announced the launch of SiRFInstantFix, a "unique service that minimizes the start-up wait time for GPS systems. SiRFInstantFix provides consumers with the ability to turn on their SiRF-based navigation devices and achieve the first fix in as fast as eight seconds...".

Not that it's related, but it seems my wish of seeing a GPS solution combining the power of SiRFstarIII (tracking down to 14dBhz or -159dBm) and the LTO (Long Term Orbit) technology of Globallocate (website), first used on a consumer device on the HP hw6515, to overcome the physical requirement of a minimum signal level from the satellite of 28dBhz to download ephemeris data, is about to come true. Great news for the end user, although one can wonder how SiRFInstantFix will play along with Globallocate's LTO/"Extended Ephemeris" patents that seem to cover this field. The PR does not mention any cooperation between the two companies......
According to the PR, SiRFInstantFix is "available now", but it is not clear if and which current SiRFstarIII based devices can benefit from it or whether an upgrade will be required or available.

A busy
news day for SiRF as they also announced SiRFlinkI, the first combined GPS and Bluetooth chip as well as the acquisition of Impulsesoft, an innovator in Bluetooth technology.

Lu : 30161 | Suite de l'article... ( mots)

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