GPL-GPS is currently only supports the Zarlink GP4020 GPS receiver chip, which is an ?ARM7TDMI 32 bit processor with an on-chip GPS correlator peripheral. The chip was previously owned by Mitel, and then previously owned before that by GEC Plessey.
- GP4020 home page
- Cheat sheet for the GP4020 - Things That Aren't Obvious.
- GP2015 GPS RF front end, which takes the 1.575GHz signal, downconverts, and spits it out as a ~ 5MHz 2 bit digital signal.
What about other GPS chipsets? We're currently eyeing the Nemerix chipset since it has a embedded LEON (open source SPARC v8) processor, which already has eCos ported to it. We'll eventually get to that, but first we'll finish polishing the GP4020 port which, uh, may take a while. heh.
We'd really love to do a version of GPL-GPS to other chipset manufacturers, like SiRF or Trimble. However, first these chipset manufacturers will need to release the documentation on their chips in some open way; e.g., release their datasheets to the web. Then we'd gladly port the GPL-GPS code. Unfortauntely, these chipsets now currently require a NDA and an ungodly expensive development kit if you want to use them. And then, of course, because of the NDA you can't share your work with others.
GPL-GPS software development is focussed on SigTec Navigation's MG5001 OEM (Original Equipment Manufacturer) GPS receiver. OEM means it's a circuit boad and nothing else: no keyboard, display, no antenna, etc. We chose the MG5001 because of it's nice layout, decent memory layout, and access to many of the GP4020's pins via a 51 pin connector.
GPL-GPS, however, should work on just about any Zarlink GP4020-based receiver. Some of these receivers are:
- SigTec Navigation MG5001: Official GPL-GPS receiver. (Here are some notes on the MG5001 receiver).
- SigTec Navigation MG5003: A smaller receiver (boots from serial EEPROM!), but no 51 pin connector.
- Novatel (was CMC) SUPERSTAR II: A very nice GP4020-based board, but no 51 pin connector.
Usually you need more than just the GPS board - you need a "carrier" board with power supplies and RS-232C line converters, maybe even a USB to serial converter onboard. Here are our open hardware development, or carrier boards:
- SigNav MG5001/3 Development Board Rev. 2: An improved open hardware development board.
- SigTec MG5001 Receiver Development Board: An open hardware development board/carrer for SigTec Navigation's MG5001 GPS recevier
- Parallel port to JTAG Interface: A board to connect a PC's parallel port to the JTAG pins on the GP4020.
- +20dB in-line GPS amplifer: http://www.wi-sys.com/products/accessories/2901.php
- In-line RF switch: http://www.wi-sys.com/products/accessories/2803.php
- 1-3GHz bias T: http://www.wi-sys.com/products/accessories/2902.php
- Poor website, but lots of GPS stuff: http://www.gpssource.com/
- Spiral antennas: http://www.sarantel.com/
- Decent pole mounted external antenna: the Garmin GA 29 - can't find a website on the garmin site for it, though