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As of March 2008 the two best GPS chipsets available is the SiRF Star III and MTK MT3318. They offer fast initial fix and can utilize weak GPS signals by massive parallel correlation computing power [1].

Holux GPSlim 240 GR-240

Gps holux gpslim 240 unit.png Gps holux operation.png

  • Chipset: SiRF Star III - GSC (single chip)

This is a very small and light Bluetooth SPP (Serial Port Profile) compatible unit with USB support (USB-to-SERIAL cable). It features massive correlation computer power and excellent sensitivity.

The small size makes it idea for internal installation inside the Eee PC. The small power-switch on the side can accidentally be turned and disturb the operation of the device if it's in the pocket or backpack.

Note: Initially I had problems getting it up and running from a cold start [2]. In HyperTerminal the COM-port was outputting unusable skewed data. After draining the battery (disconnecting the battery) it worked fine, instant lock.

Disable DGPS

To disable differential GPS correction, either use the SiRF Demo program [3] or these commands to disable WAAS/EGNOS/MTSAT [4]:

$PSRF100,0,38400,8,1,0*3C ; Switch to SiRF mode

SiRF commands

Holux M-1200

Gps holux m-1200 unit.png Gps holux data cable.png

  • Chipset: MTK MT3318

The M-1200 looks and works much the same as the GPSlim 240. It's based on the latest MT3318 chipset and features 32 channel satellite tracking queue/pipeline, 1 to 5 Hz update frequency, and lower power usage.

Enable 5 Hz

The default update frequency is 1 Hz, or once per second, the MTK chipsets support 5 Hz.

$PMTK300,200,0,0,0,0*2F ; Set 200 millisecond update frequency
$PMTK251,115200*1F ; Baud rate 115200
$PMTK300,200,0,0,0,0*2F ; ; Again set update frequency


MTK commands

Other chipset brands

  • SkyTraq
  • Nemerix
  • uBlox
  • uNav
  • Sony
  • Fujitsu


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