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gpspassion
93402 Posts |
 Posted - 14 juin 2007 : 00:06:18
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UPDATED20080520 : New version of the Venus chipset apparently, the Venus634LP : >> LINK <<
"...Taiwan-based SkyTraq recently introduced its Venus634LP GPS receiver, a single-chip GPS receiver using the company's low-power Venus6T GPS architecture.
Measuring 10x10x1.2mm, the Venus634LP integrates LNA, SAW filter, RF front-end, GPS baseband, 0.5ppm TCXO, RTC crystal, LDO regulator and passive components. A complete GPS receiver requires only an antenna and Venus634LP, noted the company..."
[REVIEWED] - SKYTRAQ BASED GPS RECEIVERS
AGPS - 44 Channels - 159dBm
From left to right : BT100X, BT100Y, BT760Y, Qstarz BT1000
UPDATED 20071023 - New AGPS utility for PocketPCs and PCs, >> here <<
UPDATED 20070911 - I received 100Y and 760Y test units last week and have been putting them through their paces. The big attraction on these units is the AGPS (Assisted GPS) feature as it marks its first appearance on Bluetooth GPS receivers. It is "Offline AGPS" like SiRFinstantFix used on some PDAPhones and AIOs or NEX by NemeriX and Assist Offline by uBlox, both unavailable on shipping units at this time. You can read more about "Offline AGPS" in this topic in the technical section.
1. AGPS Testing
AGPS works as advertised with Warm TTFF (equivalent to getting started in the morning) coming in between 4 and 8 seconds with good signal conditions (without AGPS, Warm TTFF is around 30 seconds at best), and even in degraded conditions (signal in the high 20s dB-Hz) it still manages to lock in 20 seconds when a Bluetooth without assistance would take 60+ seconds or not lock at all. This certainly adds a lot of value and enhances the user experience. The downloaded eph.dat is good for 7 days, but the accuracy degrades over time so update the data each time you get a chance.
The AGPS Update utility
2. Tracking Performance
A. My preliminary in-vehicle tracking tests done with an intermediate v1.2.101 firmware (units currently ship with v1.2.16 I believe) were showing some occasional drifting (likely due to multipath) but this has been fixed in the latest v1.2.103 firmware as can be seen below. The BT100Y performed on par with the other reference receivers I had along for the comparison, the MTK/Qtarz BT1000(iBlue747) and the SS3/Globalsat BT-338, the latter showing some occasion "overshooting" problems.
Some clean tracks in a dense urban area where previous generations struggled
A sharp turn in a narrow street produces some "overshooting"
Another sharp turn with better results
The signal analysis table shows that neither lost the fix in these narrow streets. The Skytraq impresses with its high level of average satellites in the fix that will give it more margin when the conditions worsen. The signal level differences are likely due to different reporting methods, SiRFstarIII is known to understimate by about 3dB-Hz
B. Pedestrian Use : I have completed some pedestrian testing too and while it performed ok when given a clean start, it seems to get confused when there is a long "blackout" (i.e. underground train) and could not get back on its feet unlike the SiRFtarIII and MTK systems. This looks like a bug and it has been reported to Skytraq who are investigating it. To avoid this problem, you should turn the receiver on and off before using it and with the AGPS data you'll get a quick fix.
Performance comparable to SiRFstarIII and MTK in this urban area
But the 100Y cannot resume proper low speed tracking after spending 20 minutes in an underground train
3. Battery Life
The battery life of the 100Y was tested at 17h55’ and 18h08' of continuous use, so with the 950mAh battery that’s a ratio of 1.13 that falls between the 1.5 of the MTK on the Q818 for instance and the 0.7 of the SiRFstarIII (on the Globalsat BT-359).
4. Useful Tools
- AGPS Update Utility : link
- Advanced Testing tool : link
- New AGPS utility for PocketPCs and PCs : link
5. Availability
- BT100Y at Semsons for $60
- BT760Y at Semsons for $65
GpsPasSion Club members get 10% off at Semsons
Questions, comments ?
 
While some GPS Chipset designers are being bought, Globallocate by Broadcom on June 12th (PR) or NordNav by CSR on January 15th (see PR), new designers are appearing. We had MTK in 2006, see this article and 2007 is bringing us SkyTrak.
Little is known about this new SkyTraq Venus 5 chipset so far other than with its -159dBm sensitivity rating it joins the ranks of the "high sensitivity" chipsets (SiRFstarIII, uBlox4, MTK, GL Hammerhead, Nx3 - in order of appearance) with a record number of channels at 44, likely for acquisition and fewer for tracking. The first GPS receiver with the Venus 5 will apparently be the WondeProud BT100Y whose battery life rating of 17 hours for a 950mAh battery shows that this is fairly frugal chipset. Stay tuned for a review of this receiver on GpsPasSion in the coming weeks.
Questions, comments ? |
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Neighbour
Russia
1 Posts |
Posted - 14 juin 2007 : 15:24:19
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| Just wondering... How is it possible for a small start-up company to develop a new, up-to-date product with good parameters from scratch? I think it's just a team of developers who left some other chipset maker in hope to be bought by a GPS market giant company :) |
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gpspassion
93402 Posts |
Posted - 14 juin 2007 : 15:34:33
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| Possibly, I was also wondering about that for MTK, but they appear to be Taiwanese companies where there were no existing chipset designers AFAIK ? I guess what matters to us is if these new chipsest perform well and the MTK sure does ;-) |
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pbgp
66 Posts |
Posted - 14 juin 2007 : 20:10:25
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Could anyone explain me why is "44 channels" useful for ? More than satellites actually in orbite ? ;-)
"950mAh battery": with 1.8V or 12V ? This figure of 950maH doesnt't mean anything if you don't specify voltage... |
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gpspassion
93402 Posts |
Posted - 14 juin 2007 : 20:17:17
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1. See the technical explanation linked in the Nx3 article
2. Oh really ? What matters is the battery life you're getting with a 950mAh battery, whether it uses 12v or 1.8v is a moot point for the end user, if you really need to know 100% of the batteries of Bluetooth GPS receivers are rated at 3.7v. |
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pbgp
66 Posts |
Posted - 15 juin 2007 : 11:58:19
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1) I understand here http://www.gpspassion.com/forumsen/topic.asp?TOPIC_ID=36196#217429 that a few more channels could be useful, but 32 more seems a lot !
2) because a 950mAh 12V battery will be nearly seven times bigger (and will last sevent times longer, with a good power conversion scheme) than a 1,8V one ! We should talk Wh (Ah * V) when speaking battery capacity, it is a better sign of energy included. Of course, if you are certain that it is (and will stay) always 3,7V , it's of course not useful... But be careful of commercial information !
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gpspassion
93402 Posts |
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pbgp
66 Posts |
Posted - 18 juin 2007 : 20:02:42
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...and this is why we read you !quote:
Originally posted by gpspassion
100% of the batteries of Bluetooth GPS receivers are rated at 3.7v.
Are you sure ?
Because here http://www.gpspassion.com/fr/articles.asp?id=143&page=2 I read 4xAAA battery for the uNAV, which makes 4,8V (with NiMh cells) or even 6V (with alkaline) for me. |
Edited by - pbgp on 18 juin 2007 20:13:03 |
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gpspassion
93402 Posts |
Posted - 18 juin 2007 : 20:33:45
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| No battery pack on that one so it probably doesn't count as an exception, anyway we're largely OT here but feel free to start a new thread about batteries and their ratings. |
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gpspassion
93402 Posts |
Posted - 18 juil. 2007 : 21:18:38
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I met with Oliver, one of the founders of Skytraq, at the beginning of July when he visited Paris and we took a "beta" version on the "GpsPasSion Test Track". Very fast acquisition thanks to the built-in AGPS but the tracking will need some tuning before some final testing can be performed.
  
Field test on the "GpsPasSion Test Track" for the SkyTraq based Wondeproud GPSr |
Discounts and Assistance/Réductions et Assistance (Club GpsPasSion) / Où commencer? |
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Niko
Australia
56 Posts |
Posted - 26 juil. 2007 : 04:23:48
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| The question I have is, does any of the manufacturers you have mentioned in this topic have same issues as MTK 32 whilst walking? I know SiRF III do not have the same problem. |
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accelerate
7 Posts |
Posted - 02 août 2007 : 01:06:50
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Hi all,
I recently bought this receiver as "SkyTraQ100 44 channel" on eBay and made comparisons with the Nokia LD-3W (a SiRF III NMEA unit) on walking and driving. From my tests I can confirm the better operation on weaker signals (with VisualGPS). Starting times cold/warm/hot are felt negligible faster.
Static Navigation seems to be activated on the LD-3W (and no way to deactivate it), but not on the SkyTraQ, which is my plus for the latter.
Accuracy of heights: The LD-3W gives heights with a deviation of approx +-7 m (compared to the maps) which is pretty good enough for walking (Carinthian mountains,...). The SkytraQ gives heights which are approx 40-50 m too high, and no correction. Since the chipset is new, and on the accompanying CD there are only pdf's, I don't know the firmware version nor any tool to configure ur update.
Did anyone have the same experiences? |
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gpspassion
93402 Posts |
Posted - 02 août 2007 : 01:13:35
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Interesting that you were already ablt to buy a SkyTraq based receiver, do you have the link to that auction, I coulnd't find it with a search.
Anyway good to hear it's working well. How is the battery life ? The altitude problem you describe could be MSL altitude what do you see in the NMEA GGA field #10 ? That's where the correction is if memory serves. |
Discounts and Assistance/Réductions et Assistance (Club GpsPasSion) / Où commencer? |
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accelerate
7 Posts |
Posted - 03 août 2007 : 09:29:54
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Current auction at eBay selling the same item:
http://cgi.ebay.at/ws/eBayISAPI.dll?ViewItem&item=180145075680
Regarding the heights here are the logs from a voyage on lake Weissensee in Austria. There was good reception, both receivers were placed on the upper deck of the ship 10 cm apart from each other. MSL of the Lake is 929m, plus approx 3,5 for the deck.
=== LD-3W ===
$GPGGA,093902.000,4642.5752,N,01320.1514,E,1,08,1.1,929.6,M,46.0,M,,0000*53
$GPGSA,A,3,27,28,13,08,02,25,29,10,,,,,1.9,1.1,1.5*34
$GPGSV,3,1,12,27,75,065,30,08,72,206,41,10,52,300,43,25,51,056,48*7D
$GPGSV,3,2,12,13,31,084,44,02,23,237,41,29,16,281,39,28,15,162,35*77
$GPGSV,3,3,12,24,13,321,18,04,10,206,,23,04,092,,26,02,277,30*7F
$GPRMC,093902.000,A,4642.5752,N,01320.1514,E,7.92,91.63,270707,,,A*5B
=== SkyTraQ ===
$GPGGA,093902.983,4642.5740,N,01320.1516,E,1,08,1.1,987.8,M,,,,0000*0B
$GPGSA,A,3,27,02,25,08,10,13,29,28,,,,,1.9,1.1,1.5*34
$GPGSV,3,1,12,27,76,066,34,02,24,238,46,25,52,057,48,08,72,206,40*77
$GPGSV,3,2,12,10,52,301,33,13,32,084,47,23,05,093,15,29,16,281,34*79
$GPGSV,3,3,12,28,15,163,43,24,13,322,,04,11,206,,26,02,277,*74
$GPRMC,093902.983,A,4642.5740,N,01320.1516,E,007.7,086.3,270707,,,A*64
I submitted a request to Skytraq an they quickly responded on thursday 2nd:
... Currently the GPS firmware does not support geoid correction, so the reported altitude is GPS height, not mean sea level altitude.
We'll provide our OEM customer an update firmware with geoid correction and mean sea level altitude next Wednesday; fixing the problem ...
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gpspassion
93402 Posts |
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accelerate
7 Posts |
Posted - 07 août 2007 : 10:52:07
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I did a test regarding continous operating time with fully charged battery. Results: 14h50m and 14h35m. The battery had already 10 full (dis)charging cycles.
For the firmware update and tool (ephemeris upload, ...) I mailed Wonde Proud, but did not get an answer yet. |
Edited by - accelerate on 07 août 2007 10:54:21 |
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[TOPIC] SkyTraq GPS receivers with AGPS - Reviewed
