GPS

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As of today (March 2008) the two best GPS chipsets available are 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].

SiRF Star III

Disable DGPS

To disable differential GPS correction, either use the SiRF Demo program [2] or these commands to disable WAAS/EGNOS/MTSAT [3]:

$PSRF100,0,38400,8,1,0*3C ; Switch to SiRF mode
$PSRF151,00*0E ; WAAS/EGNOS/MTSAT Off
$PSRF151,01*0F ; WAAS/EGNOS/MTSAT On

SiRF commands

MTK MT3318

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

Hacks

MTK commands

Other chipset brands

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

Tools

Navigation Software

References