internal GPS MOD
This mod teaches you how to place a GPS internally in your Eee PC. If you don't wish to open your unit, you can buy an External GPS Receiver that works just as well.
ModMyEee.com recommends the "Navibe USB GPS". We have tested and it works great with a 7"Eee PC !
Wouldn't it be cool to have a Eee PC with a integrated GPS unit? Yes! I certainly thought so. Doing some research, I found a GPS DIY kit on Ebay GPS-R02-DIY for a decent price. The bulk kit included a GPS unit based on a NemeriX chipset, antenna with 3 meter cable with mmcx connector, mini-CD-R driver disc, USB cable, plastic case, and two screws. Suitable to be permanently installed in a boat or car.
The GPS board itself was quite big and I had to strip it down as much as I could. Removing the LEDS and two connectors was easy, getting the board shorter was a bit harder. The 3.6v standby battery could easily be connected off the board, and cutting the side of the board freed up some valuable dead space.
The antenna was the most critical part and had to be fitted outside the shielded Eee chassis. Before ordering the kit I was hoping it would fit in the display, and guess what, it just did by a small margin. The crystal dielectric filter [2] on the underside had to be moved to the side of the main antenna body, and if all is good the RF characteristic won't suffer to much because of that.
Update: I had to try three times before I finally desoldered and handled the filter properly without damaging it, much. Although the filter is mounted correctly this time, it seems that the signal is weakened or lacking because the GPS module only sees 2 satellites in view. The crystal could be damaged or the relocation didn't work out as I hoped it would. If I can't figure out the problem, I'll try to source a new suitable GPS module (SiRF Star III or MTK).
If you're going to try the relocation, use a heatgun and hold the antenna by the filter using a plier and wait for the body to drop. When relocating it, first solder wires to the filter and then the antenna body. The two middle solder pads does not handle excessive heat or force, be careful.
To fit the antenna next to the display, I had to cut away 3 stubs holding the cables in place and a placeholder for the display unit. None of these stubs are voiding the integrity of the display, it all fits and holds together as stock.
I stripped the outer insulation of the RG-58 coaxial cable and replaced it with Kaptop electronic tape. That made it less rigid and easier to work.
Routing the webcam and speaker wires to make space was pretty easy, lots of slack. I fitted the coax cable first, then soldered the core and shielding to the antenna.
After some more re-adjustments and re-positioning the wires, it turned out quite good I think. The webcam wire placed between the locking mechanism and antenna is not squeezed as it might seem.
The antenna unit is flush to the display and the front panel clicks into place perfectly.
The placement for the main unit needed to go through a few trails and errors before figuring out the only space large enough to house the unit was over the ethernet controller, next to the audio and amplifier chip.
It is a tight fit when closed, but there is still space lef over the unit. Though not much. It's powered by 5v.
When everything is finally installed, it looks like this.
To get the GPS working in Windows XP, I had to install the included driver for the Prolific PL-2303 Serial-to-USB transceiver. The GPS support 16 channels and the clear-text de-facto NMEA standard, which means most GPS mapping programs work with this module.
A couple of GPS tester programs to verify the connection and GPS module was also included on the mini CD-R.
Current status: I have problems acquiring a lock, the module only sees 2 satellites. It could be a problem with the relocation of the crystal. If I can't figure out the problem, I'm going to find a suitable SiRF Star III or MTK based unit.
Specifications:
Datasheets (thanks Simon Stapleton) (mirror):
- Nemerix NJ1030A baseband processor
- Nemerix NJ1006A RF front end
- LEON2 SPARCv8 architecture
- GRMON and other associated tools for LEON
- RV80 GPS Engine Board User Manual
Pin-compatible (or nearly so) GPS modules:
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