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Pretec Compact Flash LP GPS Card Review

20th December 2002

 Reviewed by: Dave Burrows



You may recall back in September 2002 we reviewed the Pretec CF GPS Receiver.  In our tests this came out as quite a good GPS Receiver, however we couldn't at the time get our hands on the new LP version as it had only started hitting the stores.


Thanks to Richard at Jactron, we've managed to receive the new LP edition (LP stands for Low Power).  So why review what essentially is the same card twice ?  The Low Power edition is radically different to the original popular Compact Flash card that Pretec sells.


One of the main features obviously is it sports a new Low Power chip.  Secondly, it's a soft GPS receiver.  Do you remember a few years ago on the PC, the internal modems started being shipped as WinModems ? 



 Pretec Box

These were essentially cutting back on physical chips on the internal modem cards and relying more on PC's memory and processor from within Windows to drive the modem. 


This is how Pretec have managed to cut power consumption in their new LP design.  By removing some of the main power hogs that are sitting on the circuit board, and by utilising the Pocket PC's processor and memory enables Pretec to produce a low power model.  Thirdly the LP edition can only support up to 8 satellites at any one time, compared to the usual 12 satellites we now see in most GPS receivers.  Although on an average day, my TTFF's tend to be around 7-9, I have had higher with 11 on quite a number of occasions.  The more satellite acquisitions it can achieve, in theory the more accurate triangulation you will see (but this isn't always the case).

When you install the Pretec drivers, you get a GPS Server driver installed which boots on soft reset of the Pocket PC and displays on screen trying to detect the Pretec LP card.  You can disable this if you are not going to use the LP card for that session, but the only way of permanently disabling this on start up is to uninstall it.  This is the main conduit that allows the LP GPS Receiver to be able to communicate and use the Pocket PC resources.


Pretec CF LP GPS Card


iPAQ, Pretec CF LP GPS Card


Initial Findings and Installation Problems

Unlike the original Pretec card, we had no problem installing the drivers which came on the LP CD.  Luckily and thankfully Pretec have now got this right, and the drivers on the CD work, and work well once installed.  However there was a beta version 2.03 available, and a 3970 Service Pack available at the C1 Tech FTP site.  We have found that the boot-up process on the Pocket PC after completing a soft reset is extended now due to loading the GPS Server driver which takes considerably longer and does slow the iPAQ 3850 down.  You can actually watch various parts of the screen re-painting gradually showing that this is utilising the Pocket PC's processor and memory quite heavily.


One thing we did find is that each time we started the Pretec driver to initiate a TTFF, in a cold state (powered off for 4 hours) it should have had Almanac data but would have no or little accurate Ephemeris data, we still found a TTFF taking around 20-45 minutes.  This was in a clear open sky and not blocked by any objects or having GPS signals bouncing off of buildings.  Knowing full well that most of these receivers (including the LP) has a backup battery, and that sometimes these do need to be charged, discharged and re-charged before they'll store Almanac and Ephemeris data, we left this over several days to charge it up for a total of 4 hours.  This helped immensely and resulted in some fairly respectable TTFF's.  Still 20-45 minutes is a very long time seeing that Almanac data in theory if received in one piece takes around 12.5 minutes to receive and Ephemeris data around 30 seconds.  One thing we have noticed, even once Almanac data is stored in the receiver on power off, is that even on warm/cold starts where as you would normally see a spurt on most receivers where you'll get 2 or 3 satellites appear within 20 seconds, the Pretec LP does seem to take longer, and we have consistently found that around 1 satellite per minute will be displayed, as it gradually builds up steam.

Problems Encountered ?

One problem several of our readers have faced is that running this card on the 3900 series iPAQ's due to the new design and Bluetooth, initially it does seem to have a problem.  Pretec have confirmed that there is no compatibility issue with the Compaq iPAQ 3900 Series or the Fujitsu Siemens Loox 600 PDA, providing v2.0 of their drivers are used with the Loox or v2.3 Beta 1 or above is used with the iPAQ 3900 Series as these versions will resolve the COM Port issues.

Software Included

Unlike the original Pretec offering, the Pretec LP no longer comes with AutoRoute 2002, however it does come with the latest TomTom CityMaps 2003 Edition for the Pocket PC.



The LP edition is much smaller than the original Pretec Compact GPS Receiver.  This has been partly achievable from being able to use less circuitry on-board.


Technical Details



  • Ultra Low Power Consumption (under 40mA in running mode)

  • 8 parallel satellite-tracking channels for fast acquisition and reacquisition

  • Support for true NMEA-0183 data protocol

  • Enhanced algorithms provide superior tracking performance in urban, canyon, and foliage environments

  • Maximum navigation accuracy achievable with the Standard Positioning Service (SPS)

  • Meets rigid shock and vibration requirements

  • Automatic altitude hold mode from three-dimensional to two-dimensional navigation

  • Automatic cold start acquisition process

  • Built-in Antenna

  • Data retention with Li-Ion battery inside

  • Reversed straight MMCX subminiature, snap-on, coaxial RF jack receptacle

  • CFA compliant


  • CompactFlash Type I 102.9 x 47.7 x 30.3 (mm)

  • Weight 70g

  • Operating Temperature 0C~+70C

Pretec LP's Compact Size


  • Hot Start: 20 sec, average

  • Warm Start: 45 sec, average

  • Cold Start: 130sec, average


  • NMEA 0183 v2.2, GGA, GSA, RMC once per second. GSV once per 5 seconds. Baud rate is 4800bps, 8 data bit, no parity bit, 1 stop bit.

Operating System:

  • Currently only compatible with Pocket PC's running the ARM and XScale processors (such as iPAQ 3600-3900 Series, HP Jornada 560 Series, Casio E-200, Toshiba e540 etc)


Compaq iPAQ 3970 Test

This test was performed by Pretec themselves using the GPS drivers v2.4.  This shows a 5 satellite fix on a Compaq iPAQ 3970.

  • Platform:IPAQ 3970+ CF slot Jacket,without connecting to EXTERNAL antenna

  • GPS receiver: GPS-LP

  • Test environment: Beside the window,8F,

  • Result: More than 5 satellites can be fixed.

  • Date/Time: Dec/17/2002,

  • 11:50AM(Taiwan Local Taiwan)

  • Test Location: Taoyuan Hsien,Taiwan.

  • Test  software: GPS-monitor

  • Software version:Ver2.4

If you still find that on a Compaq 3900 Series iPAQ that the Pretec LP card still does not function, you will need to dive into the registry and make the following change.  Please note it's always best to backup the Pocket PC and registry before making any of these changes.


1) On Pocket PC, goto Explorer and navigate to 

My Device\Programfiles\Pretec\CompactGPS-LP folder, and execute GPS-LP2.4 SP1.exe

2) A message box will pop up, and click “Yes” to install patch file for IPAQ 3970 PDA.
(This patch file will remove IPAQ consumer IR UART)

3) Soft Reset 3970


4) Double click GPS_Server

Update 23-Dec-2002

I've had a note back from our friend Enrico Pappolla over at PocketPC Italia who has tried the instructions above and this has resolved the problem in getting the LP to work on a 3970.


Latest Driver Versions

In writing this review, the drivers had reached version 2.4 Beta 2.  These can be downloaded from the C1 Tech FTP site at ftp://coneguest:@ftp.c1tech.com.tw/FAE_Support and we have a link direct to this in our downloads page.


Final Thought

We found the Pretec LP GPS Receiver to be slower in initial acquisition time compared to many of the GPS receivers we have tested in the past, and where we would normally see a 7-9 satellite fix on a 12 sat receiver, we were finding around 4-6 on average with the Pretec LP.  In general once over the initial teething problems, we found it to be a good receiver, although there were some canyon effects, these weren't as bad as we had expected and the receiver did receive a constant fix most of the time.  When a fix was lost, the receiver took around 5 seconds for re-acquisition which is quite good.  If you're starting out in the world of Global Positioning Systems for the Pocket PC, and are looking to keep costs down or are looking for a low power consumption which gives you full mobility to go where you want giving you better battery performance, then the Pretec LP is probably for you.  One thing to bear in mind is that although the manufacturer TTFF's quoted are pretty standard, we found the TTFF's to be slower than advertised and slower in comparison to other Pocket PC GPS Receivers we tested, although TTFF's aren't everything.  However Pretec do say a way to speed up the slow TTFF's is to use the external optional antenna with the Pretec LP card.


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Pocket GPS Reviewer

Dave Burrows

Pocket GPS Reviewer Website

Dave Burrows.com




Windscreen Suction Mount Strength

Not Supplied

Air Vent Mount Strength

Not Supplied

Car Power Cable Quality

Not Supplied

Overall Rating 70%

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