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Review - Fortuna Pocket Xtrack
Posté le 14 septembre 2003 à 23:37:45 par gpspassion.

Fortuna Pocket Xtrack "Two-in-One" (IIe/Xtrac)

The Pocket Xtrack CF GPS was announced by Fortuna at the beginning of August - news. This is the third Fortuna CF GPS after the PocketTrack IIe and the PocketTrack IIe/LP. It stands out as the first "dual mode" GPS, a standard "ST" mode and a high-sensitivty "XT". It brings together two state of the art technologies in a single package, which is convenient of course, but also economical, since the Pocket Xtrack costs barely more than an "ST" CF GPS or an "XT" CF GPS! You can get it for $168* or 149* euros (see the links in the conclusion). We'll also see that the inclusion of these two technologies is not redundant and in fact quite complementary.

On offer is the sturdy design that proved itself with the two previous PocketTrack generations. The shape of the antenna does remind one of a "rhino" to some extent, but that's far from being an eye-sore ;-). It's not the lightest or thinnest CF GPS on the market, but I can't think of any situations where that would be a problem. An Xtrac only CF GPS could be smaller (SysOnChip CF GPS Plus or Rikaline 6021-X6), but not a IIe/LP, at least with the current technology. Exact specs are 93,3x42,8x33=132cc for about 60 grams.

Operating Modes- ST and XT
The Fortuna PocketXtrac offers two operating modes between which you switch with a simple...switch located in the back of the GPS. According to Fortuna, it was placed in the "inserted" part of the CF card to ensure that the change occurs when the GPS is stopped, to avoid crashes on the GPS and the PocketPC, due to the use of different electronic circuits. My test model requires the use of a paper clip, but the shipping version can be operated with a stylus (see picture)

The "ST" Mode (IIe/LP)
The "ST" mode relies on the proven SiRF IIe/LP chipset that first appeared on the Emtac Bluetooth GPS in late 2002 and now equips all the "high performance" GPS receivers on the market. All's been said and written on this chipset that offers both excellent performance in terms of TTFF (time to get a position), sensitivity, tracking of sudden heading and speed changes, and optimized power requirements at 80mA (versus 160mA on the previous IIe). It also offers room for growth with the configurable SBAS and Trickle Power modes. I'd venture we're close to perfection for road navigation in normal conditions, i.e. with a reasonable view of the sky. If reception conditons become marginal and the GPS starts losing the fix, an external antenna placed on the roof can be added (see picture of the MCX plug below)...and then what? Well until recently, that's where GPS Assisted Navigation stopped!

Since the spring, one could use an Xtrac based GPS, but with the Pocket Xtrack all you need to do is "flip the switch"!

The "XT" mode (Xtrac)
GpsPasSion was the first to announce the arrival of this ground-breaking GPS receiver with several preview reports compiled here; let's sum it up. The idea behind Xtrac seems pretty straightforward: take the excellent IIe/LP chipset and "push" it by adding a more accurate "cristal" and work with much fainter satellite signals (16db versus 28db on the IIe/LP) to be able to get a fix in very degraded reception conditions (urban canyons, heavy tree cover, etc...) where other GPS receivers are "blind". While this seems simple enough and apprealing on paper, it isn't without creating a few problems. Working with signals that are that faint means you're using data of a lower quality that must be filtered and processed with complex algorithms. As a result, the CPU of Xtrac GPS receivers works at almost full capacity (versus less than 50% on the IIe/LP) and the position is slightly delayed, a delay that's even more noticeable for the dynamic parameters (speed and heading). SBAS functionality is also lost in the process with the CPU lacking horsepower to cope with the required processing. Not a huge problem for road navigation or hiking, but a potentially larger one for critical GPS applications at sea or in the skies.

In the field, I must say that Xtrac is quite amazing, rarely fewer than 7/8 satellites, a fix behind a heated windshield, a fix maintained indoors, no lost fix, etc...after marvelling at these feats, one can't help but notice a delayed position while driving, speed readings that adjusts over a period of 5 to 10 seconds, slow map rotation, route recalculation that becomes unpredictable...and it isn't without regret that you switch back to the ST mode for "road use" (except when the ST mode is "blind" of course). The delay is naturally more noticeable the higher the speed, which means that for a hike or a bike ride under heavy tree cover, it will be barely perceptible and I think that this is where the XT (Xtrac) mode shines. What will be noticeable (by its absence) is the the lack of lost fixes. The same goes for a walk around town in between buldings or in narrow streets.

GPS Performance
I found performance to be on par with "single-mode" ST CF GPS receivers (Haicom HI303MMF, Globalsat BC-307, Holux GM270, etc...) and XT receivers (Holux GM270 Ultra, Rikaline X6, SysOnchip CF GPS Plus). For the "detail-oriented", a detailed CF GPS comparison is in the works.

Power Usage
The same goes for power usage, with performance being comparable to the other IIe/LP CF GPS receivers: 90mA in both modes. Using a Dell Axim set to maximum backlight, I got 2,2mn per battery %, versus slightly more (2,4mn) on the Haicom HI303MMF. By reducing the backlight a bit, the 4 hour bar shouldn't be a problem.

The ST mode offers all the usual settings of IIe/LP GPS receivers, with the choice in the protocol (NMEA/SiRF), toggling of SBAS, Trickle Power, see here for more details. The XT mode is limited to the universal NMEA/4,800 setting and does not offer SBAS for the reasons explained above. Since I wasn't able to switch to the SiRF mode that's required to access settings on ...SiRF receivers, I wasn't able to verify whether Trickle Power options were available. However, having tried this on another Xtrac receiver, it appears TP is not available in Xtrac mode.

By offering a "dual-mode" GPS with a very effective ST Mode for driving in normal reception conditions and a high-sensitivity XT mode for very poor reception conditions, where a standard GPS would be "blind", Fortuna hits a chord. Even better, you can get access to these two modes for barely more than the price of a single GPS. In the US, you can get it for $168* from Semsons and for149* euros from in Europe.

(*) These prices are valid at the time of writing on 09/14/2003 and factor in the Club GpsPasSion discounts.

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