GPS

GPS

The GPS hardware page.

Software found elsewhere (location services - see SDK.)

Description

The Palm Pre has a built-in hardware GPS, it's integrated in the radio receiver chip.

Internet has some misleading information out there because the initial tear-downs didn't spot a separate GPS chip, so reviewers thought the Palm Pre didn't have a GPS and thus must rely on cell phone tower location like so : The Pre does use the assisted GPS capabilities of the Qualcomm baseband. That means the phone will not be able to get a location fix when it is not connected to the cellular network.

This isn't entirely accurate - the Palm Pre does indeed have integrated GPS hardware, it's part of the RF reciever chip, and it uses this hardware GPS if it's turned on (enabled.)

• If the GPS is on, GPS hardware will be used with location determined by satellites.
• If the GPS is turned off in Location Services, the Palm Pre will fall back on cell tower location.

Location of Chip

The GPS hardware is physically located on the Comm board, right hand side, as part of the RF (radio frequency) receiver chip RFR6500 that is part of the OMAP3 chipset (PDF file),

According to magazine PCB007, the Pre's main comm chipsets include the RFR6500 receiver and RFT6150 transmitter. Is it possible, the GPS isn't part of the MSM6801 but rather it's part of the Qualcomm RFR6500 Receiver, also on the Palm Pre?

Phone wreck shows the RFR6500 too, in the teardown.

This Qualcomm RFR6500 supports both GPS receiving and receiving of the voice part of cellular. This GPS chip will also likely need some digital controller - therefore my conclusion that the Palm Pre's GPS receiver is inside the second Radio Frequency support chip the Qualcomm RFR6500 receiver is the one, and it's likely the processing and control for that GPS may be part of the Baseband processor (Qualcomm MSM6801A.)

There is an engineering report here. (above, engineering report article)

Where you'll find that Qualcomm’s RFR6500 is a receiver that can support both GPS and CDMA2000 cell voice reception.

• Rapid Repair shows the comm board here. (photo.)

References

• Palm announced at CES the Pre uses the TI OMAP 3430 as an applications processor.
• Here is the Omap 3 bulletin from TI - PDF file.
• Here is the mainARM chipset detail from TI - PDF file.
• Ifixit tears down the Palm Pre.
• Here is Phonewreck's parts analysis.

Mojo

Location Services

• There are Mojo methods detailed in the SDK under Location Services (and so, no need to also detail them here.) Overview: Some of the Mojo functions allow to get current location, to subscribe to services (thus continually updating coordinates) and also reverse address resolution - put in an address and return the longitude/ latitude.
• See the SDK for the current WebOS version which describes the Javascript use of Location services.

Known Issues

Southern Hemisphere

Apparently the software on the Pre may not be converting lon/lat for the Southern Hemisphere correctly. If patch becomes available, I'll update here.

Battery Life

• Enabling the GPS itself seems to consume more of the battery than when it's off.

• Results from today's test with battery meter:

Testing method

• • I'm on a 12story building in the 9th floor, in Boston Massachusetts USA. Palm Pre is near a window, and GPS gives location value (I assume it can see satellites.)
  • Time: 2-hour tests on the desk without moving the Palm Pre, nor using it in that time, Screen off in 30seconds, no apps running at the same time ( other than Battery Meter.)

• Procedure:
  • Started battery meter.
  • Battery level began at 20% discharged to 13%. Then recharged it to 20% again, and enabled GPS discharged again... once for each state.
  • Meanwhile just let the Pre sit there.

• After 2-hours in the first state, from Location services we enabled GPS for the second test.

Results below

Battery Drain Two-hour test results:
.
* GPS OFF = discharge rate 3.18 % per hour
* GPS ON  = discharge rate 3.89 % per hour
.
.
The above are my results, you can evaluate the results yourself - battery meter is freeware homebrew.

Comment: This was not moving, But, when walking /riding does it use up any more current? Assuming then it might be constantly losing / aquiring satellite signal? Further tests will be needed to determine if this is true.

This page contributed by FreeTim Last update : FreeTim 22:31, 6 October 2009 (UTC)

Potential Costs

The Palm Pre driver uses services such a RX Network "GPS on extra" to improve the accuracy, meaning that it downloads files over the GPRS connection if available. Depending on your service providers's charging plan this may mean additional costs on your bill when Location services is enabled. It is not yet known how much data needs to be downloaded or how often.

Low-level Access

The GPS chip is part of the baseband GSM module and it seems it can not or is not enabled until the modem is registered to a network. Therefore the communication with the GPS chip goes over the same port and uses the same protocol as GSM, the messages relating to both services are interleaving in the communication stream. The attempt to document this protocol is coordinated at the Research Pre GSM Modem Protocol page.

It is not yet clear whether raw unaided GPS service is at all possible on the Pre hardware, with information such as the number and identitifiers of satellites currently in view, signal strength, and other information provided by traditional GPS chips.