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Leadtek 9531 (SiRF I) GPS Receiver Review

02nd January 2003

 Review by Dave Burrows



The Leadtek 9531 is no dark horse.  It's been around for a while now, and has proven itself both on it's own and to other GPS software houses.  Leadtek is a good name behind GPS Receivers, and one that both TomTom and PowerLOC have partnered with to bundle the receiver with their latest products.




Connecting the Leadtek

The Leadtek 9531 plugs into the bottom Sync Port of the Pocket PC.  This is the same interface that the Pocket PC cradle uses which is designated as COM1.  This does mean that you do have to make sure that any external keyboard drivers that use this same sync port, or any third party accessory drivers will have to be disabled to use the Leadtek, but this is the same with all GPS receivers that use the bottom Sync Port. 


The Leadtek 9531 is both small and light weight and also very portable. This useful antenna complies with the NMEA-0183 data message standard and SiRF I binary data protocol and can be configured to work with a variety of Handheld PC, Notebook, Pocket PC, and Palm devices.


Leadtek 9531 Features

  • Based on SiRFStarI Architecture
  • 12 channel "All-in-View" tracking 
  • Cold/Warm/Hot start time: 48/38/8 seconds 
  • Reacquisition time: 0.1 second 
  • Universal connector for different PPA/pocket PC/Smart phone
  • Cable availability
    Compaq iPAQ 36xx/37xx, 38xx series
    HP Jornada 56x series
    Casio Cassiopeia E-125, E-200
    Palm Vx, M500 series
    Handspring Visor, Edge
  • Support SiRF Binary or standard NMEA-0183 
  • Magnet base for mounting on the car 
  • Water-resistant plastic housing
  • Backup battery supported

Leadtek GPS plugs into bottom

Sync Port of Pocket PC


So what does the Leadtek 9531 look like ? 

The Leadtek looks like a square block.  The cable that comes out of the GPS receiver has a suction cup moulded around the cable.  Although the base of the receiver is both magnetic and has a rubbery felt to stop the receiver slipping around the dashboard, the suction cup can help by suctioning the cable to the windscreen to hold the receiver firmly in place.


Leadtek 9531 GPS Receiver


Cable Sets

The end of the GPS receiver cable terminates in an RJ11 plug, which then plugs into an RJ11 socket.  From this point on is considered a cable set (as seen in the following photo). 


The RJ11 plug, plugs into the RJ11 socket which is on the right of the dual cable box.  This then splits into two cables.  One goes straight to the accessory socket plug which gives you the power to the receiver, and the other cable then goes straight to the Pocket PC. 


The reason why the cable set has been designed this way is not only does it give you power to the GPS receiver, but it charges the Pocket PC at the same time giving you the best of both worlds.


Leadtek 9531 Cable Set for the Compaq iPAQ 3800 Series


A closer look at the Y-adaptor box shows the RJ11 socket

Other Cable Sets Available

  • Universal connector for different PDA / Pocket PC / Smartphone

  • Cable availability

    • Compaq iPAQ 36xx/37xx/38xx series

    • HP Jornada 56xx series

    • Casio Cassiopeia E-125, E-200

    • Palm Vx, M500 series

    • Handspring Visor, Edge

    • Pocket Loox

    • O2 XDA



Serial Port:

Universal connector (RJ11)

Baud Rate:

4800 to 19200 adjustable

Input Messages:

NMEA/SiRF Binary
Set altitude, positioning, date & time, select output message and rates
Optional DGPS RTCM Inputs

Output Message:

SiRF Binary, NMEA-0183 v2.0 GGA, GSA, GSV,RMC, VTG, GLL plus proprietary messages


Embedded passive 


Mechanical and Environmental


3.0in(L) x 2.6in(W) x1.0in(H)

Cable Length:

PDA connector to RJ11: 88cm
Junction point to cigar lighter: 35.5cm
Smart Antenna to RJ11 connector: 150cm


Magnet base 


Water-resistant plastic 

Operating Temperature:

-40 C to +85 C 

Safe Storage Temperature:

-55 C to +100 C 

Relative Humidity:

5% to 95%, non-condensing


60,000 ft(18 km) 




12 channel "All-in-View" tracking
L1 frequency 1575.42MHz C/A code


Cold Start: 48 sec typical TTFF (Time-To-First-Fix)
Warm start: 38 sec typical TTFF, with current almanac, positioning and time
Host start: 8 sec typical TTFF, with current almanac, positioning, time and ephemeris


0.1 sec (Up to 30 sec blockage)

Positioning Accuracy:

30 m, 2D without SA imposed(95%)
100m, 2DRMS,with SA imposed(95%)

DGPS Accuracy:



Velocity: < 1,854 Velocity: < 1,854 km/h(515 m/sec)
Acceleration: < 4g
Altitude: <18,000m



The Leadtek 9531 performs very well under all conditions.  Our acquisition (TTFF) timings we've received when testing the Leadtek are one of the fastest Pocket PC GPS Receivers.  The only thing that beats it are the more expensive Garmin handheld receivers.


  Cold Tests
Cold Test 1 29 seconds
Cold Test 2 37 seconds
Cold Test 3 39 seconds
Cold Test 4 41 seconds
Cold Test 5 43 seconds
Cold Average Test 37.8 seconds
Warm Test 9 seconds
Hot Test 5 seconds
Manufacturer Cold 48 seconds
Manufacturer Warm 38 seconds
Manufacturer Hot 8 seocnds



The Leadtek 9531 comes in at around 160 and can be purchase direct from Tecrep who are the UK Distributor for Leadtek.  Cable sets can also be purchase for around 20 per Pocket PC cable type, allowing you to use this on more than one Pocket PC.


Purchase from

Tel: 0121 745 8960


Pocket GPS Gold Award

The Leadtek 9531 really is a superb GPS Receiver for using in-car.  It's satellite acquisition time is very fast, it's re-acquisition time is extremely fast and has a proven track record both with TomTom Navigator and PowerLOC Destinator.


The only thing that is missing is support for the SiRF II technology (which will be coming soon!). 





Manufacturers Website


Pocket GPS Reviewer

Dave Burrows

Pocket GPS Reviewer Website

Dave Burrows.com







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