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gpspassion
84985 Posts |
 Posted - 11 sept. 2003 : 20:44:13
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They were probably referring to Mapopolis Com port settings as there's no practical way of changing the COM port allocation in they system. Here's what you should do.
1. Take out the GPS
2. Launch CE Monitor
3. Plug the GPS - note the COM port # in the pop up - that's the COM port number you want to be using in all programs using the GPS.
Since it's not really a Pocket Xtrack issue, let's go here if you still have more questions.
If you see that WM2003 modem thingy, just hit dismiss it won't ask you again.
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gpspassion
84985 Posts |
Posted - 14 sept. 2003 : 00:10:01
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Wow, this is a great report and possibly the best contribution ever to the forums ;-) Thanks for taking the time.
Not much to add. From my tests, battery life is identical in XT and ST modes, which is a bit unexpected since the CPU "works harder" in XT mode. It seems you used it mostly in ST mode up to now?
GPS Assisted Navigation is a never ending amazement to me. Each time I head out for an unknown location I just tap in the address and head out...no stress, no fumbling with the maps as you write!
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dcrochet
USA
1044 Posts |
Posted - 14 sept. 2003 : 04:37:46
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gpspassion said: "From my tests, battery life is identical in XT and ST modes, which is a bit unexpected since the CPU "works harder" in XT mode. It seems you used it mostly in ST mode up to now?"
Thanks for the instant, kind feedback. That's good news that ST and XT modes should experience identical battery life. I had read that ST mode (generic SiRF LP chipset feature) is only powered for 1/10th of every second (10% of the time), which is all it needs to power-up, reaquisition/get-a-fix, and report the GPS parameters to its port/listening-software. I thought I had also read that XT mode (generic XT chipset feature) was powered more like 40% of the time, so was assuming that XT mode would see reduced battery life...but this could certainly be based upon inaccurate info. Either way, it seems that the greatest battery-power drain comes during a cold-start aquisition (TTFF) or even through multiple "warm" starts (4"+) when I start and stop the GPS manually with the Axim power button or during my curious-experimentation with different GPS software. It's been mentioned that there could be problems with using the Axim power button so indiscriminately with a powered GPS/running-software. I have not really seen any errors/problems with using the Axim power button either way. Having said that, I do expect that I'll see some errors associated with this practice at some point and will report back. Again, the only problem I've experienced is when trying to start a second GPS app while another has control of the GPS port.
Yes, so far I've really only used ST-mode for real-world applications, assuming that XT-mode will be used more for off-road/urban-canyon applications on an as-needed basis. I plan to use it quite often during my semi-controlled (semi-scientific) testing, as I've already begun playing with both in house and in basement. I will certainly be less reluctant to use XT-mode in real-world apps if the battery life is basically the same for both modes as you've experienced! 
dcrochet
Axim 400 PPC 2002
D-Link 660W WiFi
Sandisk 256MB SD
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gpspassion
84985 Posts |
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dcrochet
USA
1044 Posts |
Posted - 17 sept. 2003 : 06:13:59
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gpspassion,
Sorry about the “thought I read somewhere” stuff. I read back through and you’re correct, most information did come through this forum/site: 70% this forum (mostly yourself), 20% manufacturer SiRF Star IIe/LP chipset documentation, and 5% Deluo tech-spec clarifications, and about 5% AximSite.com>GPS Talk>JakeRich (forum). I see that I simply misunderstood the terms and therefore misinterpreted the comments and data presented. Thus, my assumptions about battery-life were largely unfounded. And unfortunately, I still haven’t come across conclusive information.
dcrochet
Axim 400 PPC 2002
D-Link 660W WiFi
Sandisk 256MB SD
Fortuna XTrack DM CF GPS
Mapopolis
Outdoor Navigator
Navio
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dcrochet
USA
1044 Posts |
Posted - 17 sept. 2003 : 06:29:50
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In the meantime, I’m attempting to sum up the differences between SiRF Star IIe/LP and SiRF Xtrac performance and capabilities as follows:
First off, some GPS terminology:
1. & 2. (source: SiRF Demo software manual (pdf))
Known: Satellite is known from Almanac information, but satellite is not currently being tracked
In View (not addressed in this source doc): perhaps refers to receiving untrackable signal; signal below dB-Hz threshold; this would generally be due to signal noise associated with atmospherics (ie. Elevation) or interference (foliage, buildings, rain clouds, other RF emissions, sun-spots, etc.
Track: Satellite is being tracked, however it is not being used in the current position solution
Use: Satellite is being tracked and is being used in the current position solution
Snap Start (not addressed in this source doc): All data valid; unit powered-up within 25 minutes of power-down/last-fix
Hot Start: Ephemeris and Almanac data both valid
Warm Start (No init): Same as Hot Start except Ephemeris cleared
Warm Start (Init): All data cleared except Almanac data
Cold Start: All data cleared including Ephemeris, Almanac, Position, and Time (stored clock drift retained)
Factory Start: All data cleared (including stored clock drift) and set to factory defaults
C/No: Recieved Satellite Signal Level in dB-Hz
PRN: Pseudo Random Noise code (SV identification) for the satellite
3. “Reacquisition duty cycle:” once every second in Trickle-mode, the GPS unit increases power and performs a reacquisition of all known satellites and produces a fix. The reacquisition takes approximately one-tenth second (10Hz) while the digital-signal-processing and fix calculation take an additional one-tenth second for a total duty cycle of 20%, before power-down to ~20mA.
SiRF (SiRF Star IIe/LP) versus Xtrac (SiRF Xtrac “stand alone software”), commonalities and distinctives:
4. SiRF Technology, Inc. makes the GPS chipsets associated with SiRF Star IIe/LP and SiRF Xtrac features. The current SiRF chipsets incorporate features like:1920 time/frequency search bins, integrated SBAS (WAAS & EGNOS), DGPS support, and an onboard ARM CPU.
5. The SiRF Star IIe/LP chipset is an advanced (higher performance) and low-power version of the Star IIe chipset which builds on the SiRF Star II architecture.
6. SiRF Xtrac is a “software” (firmware?) add-on to the Star IIe/LP chipset. Thus, it is possible to get “basic SiRF” GPS function and characteristics, as well as, Xtrac’s enhanced sensitivity in the same GPS unit. Switching between “basic SiRF” and Xtrac modes is evidently non-trivial (mechanical switch is used in the case of Fortuna XTrack DM).
7. The basic Star IIe/LP design uses one UART for GPS data and one UART for WAAS data.
8. Xtrac software reconfigures the available UART’s for simultaneous GPS data, thereby disabling WAAS.
9. Xtrac sensitivity is achieved through advanced digital-signal-processing (dsp) methods which effectively average the available satellite signals over time in order to eliminate errors associated with processing weak/noisy signals. Thus, satellites that could only be “viewed” by SiRF IIe/LP receivers in noisy/weak-signal environments can now be “used/tracked” using SiRF Xtrac methods. Specifically, SiRF IIe/LP can track as low as 25dB signal-strength, while Xtrac offers 16dB signal tracking. That’s a signal eight-times weaker (10^[(25dB-16dB)/10]) than a trackable signal using standard SiRF IIe/LP methods. This increased “sensitivity” translates into better GPS performance in urban-canyon, thunderstorm, and heavy-foliage environments. Furthermore, an “averaged” fix may be considered more “precise” than a single fix derived without such extensive error-correction – of course this, particular, error correction is only required due to a noisy signal below the normal threshold.
9a. My own experimentation seems to confirm that the signal tracking threshold documentation is accurate. Minimum tracking thresholds have consistently been:
SiRF IIe/LP: 25 dB-Hz
SiRF Xtrac: 16 dB-Hz (eight-times increase in sensitivity!)
10. Evidently, this process of reconfiguring UART ports and shifting into “averaging” mode using Xtrac “software” cannot be done on-the-fly in this generation of Star II chipsets, thus the mechanical switch on the Fortuna XTrack DM. This switching process cannot even be accomplished with power-on, and causes a subsequent “cold start” of the XTrack DM unit upon power-up.
11. Xtrac inherits a performance penalty for all this extra “processing/sensitivity/precision” which shows up as a delayed update over “normal” methods of an additional second or two. This delay may be reduced by newer bus speeds and device throughput. This delay is generally not a problem for many GPS applications, but can be a liability when quick, accurate updates are needed, such as a rapid succession of turns or cloverleaf’s associated with car navigation. In aviation, the effects could be more pronounced, but without WAAS, the current Xtrac implementation has little application in the aviation community going forward. It should be noted that aircraft position will generally trend slowly in a fairly predictable path, especially during an approach (the aviation push for WAAS). Generally, an instrument approach is required only because of an overcast/storm environment where Xtrac excels. Thus, an Xtrac-like technology with WAAS enabled might actually be desirable/useful in future aviation applications.
12. “SiRF binary” is a GPS protocol which translates GPS-derived data into “sentences” that software applications understand. The SiRF binary is much more flexible and configurable than the NMEA standard.
13. NMEA (National Marine Electronics Association) is standard which defines an electrical interface and data protocol for communications between marine instrumentation. NMEA-0183 data is sent at 4800 baud. Most all GPS application software seems to import the NMEA standard protocol, while SiRF binary support is less common among GPS application software.
14. Xtrac “stand alone software:” 68mA power draw (source: here)
15. Star IIe/LP alone: 1Hz updates, 175mA max power, Adaptive Trickle-Power mode results peak power of <60mA, with 20mA average over a 20% duty cycle (not 10% total as I had previously postulated) (source: here)
Unfortunately, all this terminology and information is scarcely enough to draw any real conclusions about differences in battery-life. On the surface, it does appear that they are admitting a slight increase in power usage (+13% increase from ~60mA to 68mA). But, without any duty cycle or time references for that 68mA value...I just don't know. These source documents are more of an advertisement than technical specifications. Please continue to correct my assumptions when you get some time -- parhaps I shouldn't attempt to be conclusive in light of the information-void on the subject of Xtrac.
dcrochet
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Edited by - dcrochet on 26 oct. 2003 22:21:25 |
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gpspassion
84985 Posts |
Posted - 17 sept. 2003 : 10:32:33
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Wow, amazing stuff! Theat beats anything I've read or...written on the subject...almost ;-)
By the way, I have now published a review of the Xtrack that answers some questions - it's here
Let's take a look:
1. Yes
2. Yes, but also suspect that it depends on the elevation and azimuth.
3. Not sure I see what you mean?
4. Yes
5. Yes, lower power but also higher performance (faster "reactivity" and more satellites in use)for some reason, especially in association with a CF GPS, less notable on a mouse GPS.
6. Yes for the software (FW is low-level softwar after ll), but there is a different "cristal" for time calculations. It's supposed to be more accurate on the Xtrac receivers. Only Fortuna has come up with a switch.
7/9/10/11 - yes
12 and 13 - this only applies to SiRF based receivers. SiRF can be seen as the "native" language of the GPS. Evermore or Garmin chipsets have their own "native" language, but there are no tools I'm aware of.
14. Where did you see that? It's consistent with the overall 80mA/90mA rated draw for most CF GPS receivers.
15. That's the IIe you're quoting here. The IIe/LP should be about half and shouldn't be very different from #14
On power usage, I've run tests in both modes with my Axim and didn't see any differcence ;-)
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btcutter
3 Posts |
Posted - 19 sept. 2003 : 06:17:42
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wow...that's detailed.
Ok, is it worth it to get the Dual mode Fortuna GPS or should I get the Haicom Hi303 MMF GPS? |
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dcrochet
USA
1044 Posts |
Posted - 19 sept. 2003 : 09:29:00
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Okay...I updated my sources with hyperlinks (see above)...but I couldn't figure out how to do a hyperlink neatly without listing the entire URL as text as I've done above?
dcrochet
Note: would be [ url="http://www.gpspassion.com"]test[/url] without the leading space.
Got it!...thanks to gpspassion 
BTW, I just read your (gpspassion) article on the XTrack Dual-mode and it is great! Very nice research and well beyond anything I've read on the unit. I hope my own numbers aren't misleading in any way...they're taken right from the manufacture's brochures on the SiRF site. Do you have a way to messure power draw, etc? Otherwise, sounds like you're in touch with much smarter folks ("insiders") than the one's who simply throw a few numbers into a brochure. |
Edited by - dcrochet on 20 sept. 2003 03:15:09 |
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dcrochet
USA
1044 Posts |
Posted - 19 sept. 2003 : 09:44:19
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Tonight, as the eye of hurricane Isabel approached (and is now passing) overhead (Charlottesville, VA), I've recorded the following using the XTrack Dual-mode gps on a Dell Axim:
Normal conditions (no storms):
SiRF IIe/LP:
Cold Start TTFF: 60 seconds avg
Upper Floor signals: 37dB avg, Viewing: 10, Using: 7
Basement signals: 29dB avg, Viewing: 9, Using: 5-6
SiRF Xtrac:
Cold Start TTFF: 50 seconds avg
Upper Floor signals: 37dB avg, Viewing: 10, Using:9-10
Basement signals: 29dB avg, Viewing: 10, Using:8-9
During Hurricane Isabel overhead:
SiRF IIe/LP:
Cold Start TTFF: 7 minutes avg!!! (avg of 3 forced cold-starts thru ST/XT switch cycles)
Upper Floor signals: 31dB avg, Viewing: 9, Using 2-5 (often 2D fix)
Basement signals: 27dB avg, Viewing: 7, Using 2-3 (only 2D fix; no tracks below 25dB)
SiRF Xtrac:
Cold Start TTFF: 50 seconds avg!!! (avg of 3 forced cold-starts thru ST/XT switch cycles)
Upper Floor signals: 31dB avg, Viewing: 9, Using: 6-8 consistently!
Basement signals: 20dB avg  , Viewing: 9, Using: 5-6 consistently! (no tracks below 16dB)
Note: the 20dB avg above is significant because the SiRF IIe/LP cannot track below 25dB, but the Xtrac tracks down to 16dB.
BTW: I've had the XTrack CF unit running Mapopolis now for 8-hours straight in my Axim on battery power (standard supplied Dell batt) and I just now lost the fix due to low battery power (quite audible event in Mapopolis; still showing 28% and good satellite tracking, but "GPS status" has changed to "Running/No Fix"). That's including at least 6 cold starts for the XTrack unit during this battery cycle. (backlight mostly off)
dcrochet
Axim 400 PPC 2002
D-Link 660W WiFi
Sandisk 256MB SD
Fortuna XTrack DM CF GPS
Mapopolis
Outdoor Navigator
Navio
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Edited by - dcrochet on 21 sept. 2003 06:29:05 |
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gpspassion
84985 Posts |
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dcrochet
USA
1044 Posts |
Posted - 19 sept. 2003 : 10:00:53
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quote:
wow...that's detailed.
Ok, is it worth it to get the Dual mode Fortuna GPS or should I get the Haicom Hi303 MMF GPS?
That depends on your application...assuming gpspassion agrees that quality and compatibility is not an issue for you. Keep in mind that only the Fortuna XTrack Dual-Mode allows you to switch between ST and XT modes (as of Sep 2003). Most folks would agree that you don't want to be stuck with only XT (Xtrac) mode for car navigation or aviation applications due to delayed position updates (car) and no WAAS (aviation). However, if you're purchasing GPS exclusively for off-road or marine applications, a lesser expensive Xtrac unit would be my choice.
dcrochet |
Edited by - dcrochet on 21 sept. 2003 06:30:42 |
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dcrochet
USA
1044 Posts |
Posted - 19 sept. 2003 : 10:09:02
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"8 hours"
Oh...that's it. I have the backlight set to full bright on battery power, but Dim after only 5 minutes. My guess is that the backlight was on about 1 hour total. Would 8 hours still be abnormal (Axim)?
dcrochet
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gpspassion
84985 Posts |
Posted - 19 sept. 2003 : 10:41:04
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1. For battery life, I haven't really run test without the BL, but 8 hours seems possible.
2. Good points on answering that "choice" question. For the reasons you mention though, if budget is an issue and you can't go for the Dual IIe/Xtrac, I would choose a classic IIe/LP over an Xtrac. I feel I would trust it more to reroute me in case I got lost in a stressful urban environment.
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Discounts and Assistance/Réductions et Assistance (Club GpsPasSion)
Best "GPS" PocketPC/Meilleur PocketPC "GPS" (affiliate) |
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dcrochet
USA
1044 Posts |
Posted - 23 sept. 2003 : 05:54:54
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Anyone been able to get the XTrack Dual-mode to use the SiRF binary protocol..yet? I'm using an Axim (PPC 2002 OS) with the GPS switch in "ST" and can't seem to start SiRF mode using: CE (GPS) Monitor, GPS Tweak, or GPS Info utilities. It seems to be stuck in NMEA 4800 mode. I've tried 4800 baud SiRF as well as 38400, and all the others. Does Fortuna have their own utility for this?
Is WAAS/EGNOS available with NMEA protocol?
dacrochet |
Edited by - dcrochet on 23 sept. 2003 15:58:55 |
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