PocketTrack GPS Review

This review covers the Pocket Track Compact Flash GPS receiver made by Fortuna Electronic Corp. The review was performed primarily on a iPAQ 3975 Pocket PC. Since this PDA does not have a Compact Flash, CF, slot I added a Dual CF memplug sleeve from PiTech. The sleeve has a CF memory/IO slot at the top and an additional CF memory only slot on the side which can be used for data and map storage.

The PocketTrack, shown above, features a standard compact flash interface and uses the SiRF Star II chipset. It has support for an external antenna using an mcx connector (located just out of view in the upper right hand corner), but the built-in antenna is pretty good so more most situations you won't need one. An exception would be some cars that have metallic windshields that can block the gps signal. The external antenna could be mounted on the outside of the car to avoid this problem. The built-in antenna is a patch type which is in the tilted area at the top of the picture.

This is a view of the insides of the pocketTrack showing the Star-2s circuit board which is also available separately. In addition to the pocktTrack, Fortuna uses this board in a mouse like gps that can be purchased with either a serial port or a USB port interface. They also make other gps products including an external antenna that can be used with the pocketTrack although any external antenna with an mcx connector and 2.5V power should work fine with this unit.

Installation and Operation

The gps arrived package in a plain box with a colorful sleeve. The sleeve contains the product features and specifications for the full product but not as configured. The full product is capable of being programmed to do many different this as is typical for an SiRF chip but is not shipped with everything enabled. Inside the box is the gps itself and a 6 page product reference manual. This manual is intended to describe the product as shipped and does so fairly well except for a few errors. I have been in contact with Fortuna and they are revising this manual to reflect the shipped product.

Installation on a pocketPC is trivial. Just plug the unit into a CF slot on the unit and you're done; no drivers, no software. On a pc you will need to download the driver file from their web site. Using it is just as easy. There are no user controls and it powers up and down automatically as it is accessed. The user's gps savy application will need to be set to NMEA mode, 4800 baud and the correct com port. For me the correct port was com6 due to the fact that I have bluetooth on my pocketpc. Other pocketpc units will generally have a lower port number. Some software will be smart enough to display the gps name itself so you might see a choice of Fortuna PocketTrack.

Terminal emulation software can also be used to view the NMEA messages. As shipped these include the GPGGA and GPRMC messages updated once per second. These sentences supply the location, time, altitude, and velocity data. The GPGSV and GPGSA messages are also transmitted every 4 seconds. The sentences provide information about the satellites themselves including the nature of the fix. Two more sentences, VTG and GLL are available if you have a program that can change this.

This is a small unit can can easily be carried in your pocket when not attached to he pocketPC. It only weighs about 2 oz. It has a builtin battery for backup of critical data but needs the pocketPC battery power for normal use. I found that my iPAQ battery lasted about 3.5 hours while powering the unit before it reached the critical lower power warning at 10%. Note that I had the battery reserve set to 50 hours for this test. (For comparison my pocketpc battery normally drops to about 75% in 3.5 hours of constant power on.)

Performance

The specifications are mostly dictated by the SiRF chipset and the unit can be expected to meet these without problems. The initial fix for a new location that is several hundred miles from the old location is not specifically specified but was within a reasonable time of several minutes in my testing. Horizontal accuracy was well within the 25 meters specified and was generally on par with the Garmin receivers I used to compare with. Vertical accuracy is not corrected for geoid differences so only reflects the ellipsoid model so it can be offset a 100 feet or even more based on where you live. In testing by the ocean in Santa Cruz California I observed a consistent -80 to -100 feet. Velocity accuracy was good for horizontal speed and direction and typically much better than most car speedometers. Direction is output only with regard to True North.

The main features under control of Fortuna included the antenna and the implementation of the SiRF chipset. These are certainly important and do effect the performance in a significant way. I found the unit was well isolated from interference and did not observe any interference from the pocketpc itself. All of the critical electronics are located above the pocketpc.

The antenna is a patch type and is located in a raised area above the main circuit board. It is mounted at an angle to the board itself. As with any patch antenna the overall performance is best when the antenna is mounted horizontally which is accomplished with the iPAQ held comfortably in the palm of my hand. However I was pleased to find that it worked very well in a vertical position in my car as well. It must have some design consideration for picking up a signal off the top edge, probably with a special design of the backplane. Overall the unit matched the performance of my Garmin etrex except for a difference in the mask angles programmed into the two units. (Garmin uses a mask angle of 0 meaning it reports but does not necessarily receive satellites very close to the horizon.) The default SiRF mask angle is 5 degrees and this seems to be the value used in this unit.

A gps reports, what is termed, a PVT solution. PVT stands for Position, Velocity, and Time. This unit mentions that it can be used as a precise time source and reports time in the NMEA messages to a precision of 1 millisecond. The box sleeve claims an accuracy of 340 nanoseconds and the Reference Manual claims that there is an output of a 1 microsecond synchronized GPS time. The 340 nanoseconds is only true for internal use so the box is a bit misleading but the 1 microsecond time was intriguing. I was never able to verify this time measurement or how to access it. I don't know if there is a pulse present on the CF interface or if one of the messages can be used to obtain this data. The NMEA messages seem to display the time about a second behind WWV, which would be pretty normal when allowing for NMEA processing.

I was able to verify operation of this unit with the following software: Maptech Pocket Navigator, Memory-map navigator, Pocket Streets and Trips, National Geographic Topo, VisualGPSCE, TomTom, Mapopolis, and several others.

Tips and Problems

  1. The following corrections should be made to the Product Reference manual. As delivered, the unit is not set up for trickle-power mode or push-to-fix mode. The power requirements are 3.3 volts and there is only one communication channel provided on the CF interface. This has been corrected in the production version.
  2. The GSA message always outputs that the gps is in 2D mode. This will be corrected in the production version of the firmware for the unit. The unit does correctly report altitude changes and is clearly using a 3D solution but the status message is wrong which may cause some software to report only a 2D fix.
  3. The chipset is supposed to support WAAS but the reference manual said nothing about this. I checked with a representative of Fortuna and they said that WAAS will be enabled by default in the production version. It was not enabled in the version I have. I will revisit this review and report on WAAS if and when I get it enabled.
  4. The serial number is a stick-on on the side of the unit. Be careful when inserting the gps into a CF slot that you don't scrape it off as it could gum up the connector inside the CF slot.

Conclusions

I found this unit to be a good implementation of a CF based gps unit. It worked as advertised for navigation, but I never tried it in a DVD player. (The packaging indicated it would work in a DVD player but I haven't seen one with a CF slot.) I suspect this is just the results of an over zealous marketing person.

The antenna design seemed quite good and worked well without regard to the user having to be particularly careful with the position but the shape of the unit is a bit unusual. I couldn't help but think that an interesting design would be to provide a hinge so that the antenna could be rotated about 45 degrees or so when desired.

This gps would be a good choice for a user wanting a CF based gps solution for their pocketpc or other WinCE unit. The internal antenna works well and there is provision for an external antenna for users who need one.

Final Notes

I have passed this reivew past the Fortuna folks for their comments, but the opinions expressed in this review are mine alone. All rights are reserved by Dale DePriest. If I find out anything further I will revise the review.

Released on Dec 5, 2002.