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 [TOPIC] "Auto-AGPS" - SiRFInstantFixII - HotFix
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gpspassion

93780 Posts

Posted - 02 janv. 2008 :  19:57:42  Show Profile  Visit gpspassion's Homepage  Reply with Quote

Autonomy/SIF v2 in action : 29 ephemeris sets calculated


GPS SYSTEMS WITH Auto-AGPS - 20081023 :
- Garmin Edge 605/705 Bike GPS (SIFv2 - with v2.20)
- Garmin nuvi 2x5 (STM/Rx Networks GPStream)
- Garmin nüvi 5xx (STM/Rx Networks GPStream)
- Garmin nüvi 7xx (SIFv2)
- Garmin nüvi 7x5 (HofFix with MTK v1 chipset)
- Garmin nüvi 8xx (HofFix with MTK v1 chipset)
- Garmin Oregon (STM/Rx Networks GPStream)
- HP iPaq 310 (Centrality Titan Chipset with Autonomy)
- Medion P4425 (Centrality AtlasIII chipset with SIF v2 - available with latest ROM update)
- Navigon 1210, 2210, 7200/72100 (SIF v2)
- Mio Moov 200 and 300 (SIFv2)
- Becker Z-101 and Z-200 (SIF v2)
- Navman S30/S50 3D - (SIFv2 - UK Only ?
News item on the portal
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.

Why use "Ephemeris APGS" ?
The idea behind "Offline AGPS" (vs SUPL AGPS) is straightforward but effective : instead of downloading the ephemeris data from the satellites, something that takes 30 seconds at best, requires a good signal level (>28 dB-Hz) and needs to be done every 4 hours, you download a 50kb ephemeris file valid for 3/7/10 days over the internet. Acquisition time in the morning goes down to 10 seconds from 40 seconds in good environments and remains at 20/30 seconds on average in challenging environments (coated windshield, dense urban environment) versus several minutes, if at all possible, without AGPS.

When you turn on your AGPS enabled GPS receiver, synthetic ephemeris data is used first and then there is a gradual switch to live ephemeris data as it becomes available (30 seconds in a perfect environment). Once live data has been downloaded it is valid for about 4 hours and it gets updated continually, but if you turn off your receiver for 4 hours, then you start from scratch again.

SiRFInstantFixII vs SiRFInstantFixI - Pros and Cons...
On paper it would seem that having the GPS generate ephemeris data in an autonomous way is better than having to download it over the internet as with SIF v1, but the catch, at least with Centrality's "Autonomy", is that you need to use your GPS regularly as the predicted ephemeris data is only valid for 3 days. Once the data has expired you'll need 24 hours for new data to be generated and in the meantime the fix will have to be done the "old-fashioned way" by downloading the live ephemeris data from the satellites with the usual constraints (30 seconds minimum, need good signal >28db-Hz, no blockage, etc...). On the other hand with SIF v1 you can pick up your GPS after a four day break, download the ephemeris data from the Internet and get a quick fix.

We'll have to see if there are hybrid v1/v2 versions of SIF, but based on the PR it doesn't seem to be the case.


FULL PRESS RELEASE : >> LINK << :
SiRF's InstantFixII GPS Technology Eliminates PND Start-Up Wait

Mobile Navigation Devices Can Have Start-Up Times As Low As 5 Seconds
Without Requiring Any Network Connectivity

SAN JOSE, Calif., Jan. 2 /PRNewswire-FirstCall/ -- SiRF Technology
Holdings, Inc. (Nasdaq: SIRF), a leading provider of GPS-powered location
platforms, today introduced SiRFInstantFixII, an autonomous version of
SiRF's original SiRFInstantFix technology that is designed to significantly
improve the start-up times of portable navigation devices (PNDs) and other
mobile navigation devices without needing any network connectivity for
assistance or updates. Available now for both SiRFstarIII GPS receivers and
SiRFatlas and SiRFtitan multifunction SoC navigation processors,
SiRFInstantFixII achieves GPS start-ups in as little as five seconds so
that mainstream consumers can begin navigating as soon as they're ready to
drive.

"Our groundbreaking SiRFInstantFixII technology makes the frequent
start-up waits for PNDs a thing of the past," said Kanwar Chadha, founder
and vice president of marketing for SiRF Technology. "By not requiring any
network connectivity or downloads, it significantly improves the daily
navigation experience for consumers of mobile navigation devices..."


Questions, comments?

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tunafish

112 Posts

Posted - 03 janv. 2008 :  00:34:53  Show Profile  Reply with Quote
so do u know if this is something that works only on the tomtom/mio's that currently have instantfix as firmware update, or would it work also on current garmins like nuvi 350 once garmin decides to update software?
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gpspassion

93780 Posts

Posted - 03 janv. 2008 :  00:43:54  Show Profile  Visit gpspassion's Homepage  Reply with Quote
Well based on what the PR says, it seems all the SiRFstarIII chipsets out there are compatible, the GPS maker just needs to roll out a firmware upgrade...and presumably purchase a license from SiRF ;-)

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Yugene

2 Posts

Posted - 03 janv. 2008 :  02:17:15  Show Profile  Reply with Quote
I had one iPaq 310 from holiday sale but cannot feel the benefits of instant fixes during daily use [morning/afternoon travelling time]. It is still similar to the nuvi I used to have, in terms of TTFF. Are there any special steps required to enable this function? Thanks.
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gpspassion

93780 Posts

Posted - 03 janv. 2008 :  02:19:59  Show Profile  Visit gpspassion's Homepage  Reply with Quote
No it works out of the box, the ephemeris data gets calculated in the background and is available to establish the fix when you turn it on. Did you use it each day and if yes, for how long?

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draca1

Sweden
22 Posts

Posted - 03 janv. 2008 :  08:15:04  Show Profile  Visit draca1's Homepage  Reply with Quote
does the ipaq 310 support SIF II already?

so would you people want SIFII or SIFI...

currently i have a tomtom go 500 which doesn't support either one, but i'm gonna upgrade it this year to a newer model.

personally i think SIFII is the better of the two, for several reasons.
1. you don't have to have an internet connection (good)
2. the difference in ephemeris data storage is not that big (4 vs. 7 days) because every time you do use your gps with SIFII it will update to another 4 days of ephemeris data, while your 7 day SIFI data will need to be downloaded again
3. even if you do not use the gps for 4 days it will just "boot normally" and take a little longer to acquire than with ephemeris, it's not that big a deal, it's still below 1-2 minutes with SSIII, and then it will update the 4 day ephemeris data again.
where the SIFI still would need you do download the ephemeris data every 7 days for it to work.

i'm all for the SIFII sounds like really good news, autonomous is good, and it's great it supports all SSIII with just firmware updates.

but i think i would like to see a Hybrid SIFI/II system which would both allow you to download the 7 day data if needed and then continue autonomously.

i wonder if tomtom will adopt sif2.
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gpspassion

93780 Posts

Posted - 03 janv. 2008 :  10:51:25  Show Profile  Visit gpspassion's Homepage  Reply with Quote
Good points, yes and the other aspect is that with "Ephemeris AGPS" after a while (not sure exactly how long) you would be doing a "cold reset" anyway since the time would be lost so the difference between SIFvI and SIFvII would fade. With SUPL AGPS you get the time from the network so it's not a problem.

As for the iPaq 31x it supports "Autonomy", see the links above, which seems to have been used for SIFv1 and if it wasn't it seems to be the same technology ;-)

Back to your points :
1. Yes
2. The difference, no, but the way to access the data is, again based on my testing of the 31x it seems you need 24 hours to start collecting ephemeris data, will check again
3. "1 or 2 minutes", yes if you are in a "good" GPS environment, if you're getting started in the morning in downtown Paris or NYC, in a car with a coated windshield you could be driving for a long time to get a fix, if at all ! That's the whole point of using "Ephemeris AGPS" in the first place, if you're in the suburbs then you don't need it ;-)





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draca1

Sweden
22 Posts

Posted - 03 janv. 2008 :  13:04:49  Show Profile  Visit draca1's Homepage  Reply with Quote
quote:
NO NEED TO QUOTE A MESSAGE DIRECTLY ABOVE YOURS, SERVER SAYS THANKS ;-) GPSPASSION TEAM
hmm could you extrapolate on this 24 hours? do you need to have it on for 24 hours for it to be able to extract any ephemeris data? then the point would be lost... IMHO.

or do you turn on your gps, let it get a good fix on the satellites and then 24 hours later it has compiled the ephemeris data?
wouldn't it be doing this every time you turn on the gps meaning every time you use it, it generates a new set of 4 day ephemeris data.

do you think the sif2 follows the exact same pattern as the "autonomy" or might it be a more effective version of it?

and as for sif1 , i've found it that it mostly seems to generate 5 day effective ephemeris data (for tomtom).. not the 7 or 10 days there are talks about.


anywho, on the sirf pressrelease it sounds like it doesn't require 24 hours to generate the ephemeris data, on the contrary it sounds like it's basically generated on the fly continously

Edited by - draca1 on 03 janv. 2008 14:13:32
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gpspassion

93780 Posts

Posted - 03 janv. 2008 :  22:28:39  Show Profile  Visit gpspassion's Homepage  Reply with Quote
Well that's the thing, I'm not certain it works in the same way as "Autonomy" on the Centrality Titan, my hunch is that it does though and if you think about it, there is going to be a delay to come up with predictive data if you start from scratch.

With SIF v1 is you have powerful servers crunching numbers round the clock and sending the data to clients when they request it. Here you have a low power mobile unit crunching data on a standalone basis. I'm not sure how it's done but I guess the system looks for a pattern over time and can then predict what it will be over the next 3 days. Once it has predictive data for all the sats, then yes it makes sens that it can update it continuously...provided you use your GPS x hours a day.

Field testing : At 10.30am this morning I deleted all the "Autonomy" related data files (sv0/1/2.eph, 795Kb each and sv0/1/2.obs, 215Kb each, and gpspara0/1/2/3, 80Kb each) on the 314 and have let it running since, 12 hours later there is still no synthetic ephemeris data available. The sv0/1/2.obs and gpspara0/1/2/3 are back at the same size but no sv0/1/2.eph yet. Let's see where it's at tomorrow at 10.30am.

UPDATE H+13 : 4 satellites popped up in the synthetic ephemeris grid
UPDATE H+16 : Total of 8 satellites with eph data
UPDATE H+24 : Total of 18 satellites with eph data
UPDATE H+26 : Total of 21 satellites with eph data

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gpspassion

93780 Posts

Posted - 13 janv. 2008 :  00:39:52  Show Profile  Visit gpspassion's Homepage  Reply with Quote
A further update, after a couple more test runs. So the iPaq 314 has a full set (29 in my case) after about 30 hours, so far so good, but unfortunately it appears that the ephemeris data is not actually usable to get a fix. In some cases only 3 satellites had active synthetic data and in other cases, none...

To troubleshoot this I erased the the .eph files and reset the unit to force a recalculation based on the available .obs files. It took about 15 minutes to get 29 satellites again, but same problem. Not sure what's going on, I sent an email to Centrality/SiRF but haven't heard back yet.

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Yugene

2 Posts

Posted - 17 janv. 2008 :  02:00:50  Show Profile  Reply with Quote
So, this autonomy is not SIF2!!?? Does anyone have any idea when SIF2 equipped PND will be available? And which brand name PND will be available first? 5~10 seconds TTFF will be very impressive and good to user experience.
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gpspassion

93780 Posts

Posted - 17 janv. 2008 :  02:09:51  Show Profile  Visit gpspassion's Homepage  Reply with Quote
Not sure what you man, at this point it's anyone's guess whether SiRF took Centrality's "Autonomy" and renamed it to SIFII or started from scratch. In any case it's interesting to look in detail at how Autonomy works as "auto-AGPS" faces the same constraints (need 24 hours for full set, valide for 3 days, etc...) regardless of what you call it.

When I first tested "Autonomy" it worked much better and the available ephemeris data was used in the fix, not sure why it's no longer the case or maybe there were specific conditions when I did my testing that prevented it from working properly.

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tunafish

112 Posts

Posted - 20 janv. 2008 :  01:32:49  Show Profile  Reply with Quote
looks like it may be a software upgrade and that mio is applying it to all their PND's in january. i wonder when garmin and tomtom will follow.
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gpspassion

93780 Posts

Posted - 20 janv. 2008 :  01:53:52  Show Profile  Visit gpspassion's Homepage  Reply with Quote
Good catch, a simple firmware upgrade makes sense yes because unlike SIF v1 it does not require a host application to download the data and be used by the GPS module to retrieve what it needs. I wonder if it means SiRF is giving out SIF v2 for free to its customers (unlike SIF v1)? In that case it should be rolled out by all of them...unless Mio are getting a special deal for working closely (and exclusively) with SiRF even though they did drop, the still unreleased, SiRFDiRect on the shipping version of the Mio A702 PDAPhone though (see separate topic).

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gpspassion

93780 Posts

Posted - 31 janv. 2008 :  13:14:56  Show Profile  Visit gpspassion's Homepage  Reply with Quote
Good news, it seems SIFII has been added to the nüvi 760 with the v2.60 software update -> http://www.gpspassion.com/forumsen/topic.asp?TOPIC_ID=106142

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gpspassion

93780 Posts

Posted - 10 févr. 2008 :  18:35:20  Show Profile  Visit gpspassion's Homepage  Reply with Quote
Nice improvements thanks to SIF v2 on the Garmin nüvi 760 http://www.gpspassion.com/forumsen/topic.asp?TOPIC_ID=102346 but maybe some accuracy issues with the computed ephemeris data.

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