On 2/17/10 6:45 AM, "Lux, Jim (337C)" <james.p....@jpl.nasa.gov> wrote:
>
> On 2/16/10 10:37 PM, "Thomas A. Frank" <ka2...@cox.net> wrote:
>
>> I don't believe that there is a 1pps available to the OS.
>>
>> The GPS chipset seems to provide a very limited amount of data to the
>> phone. For example, there does not appear to be any way to get
>> satellite status info from the GPS chip to the OS. At least none of
>> the apps I've tried thus far (and I've tried a fair number) provide
>> anything like that.
>>
>> Tom Frank
>>
>>
>
> I would guess that the GPS is an "assisted" GPS and a lot of the "smarts" is
> in the cellular system (e.g. Satellite almanac, etc.). All the thing in the
> phone does is start with a presupplied estimate of position and get code
> phase for some subset of satellites, then do the nav calculation, most
> likely with help from the cellsite.
" Most important to us GPS fanatics is of course the 3G iPhone¹s built-in
GPS. As you can see from the picture, the new location-aware capabilities
come from Infineon¹s PMB 2525 Hammerhead II chip. Accurate to within just a
few meters, the Hammerhead II ³integrates an assisted-GPS (A-GPS) baseband
processor with a low-noise GPS RF front end and multi-path mitigation to
avoid large errors in urban environments². Some have said that the chip¹s
die markings indicate that it¹s actually a Hammerhead I chip, but one
analyst involved in the teardown
<http://www.eetimes.com/news/latest/showArticle.jhtml;jsessionid=ZCHQFCWAAIH
R2QSNDLSCKHA?articleID=209000014> says that it¹s common practice for a
company to take an old chip and make routing and/or connection modifications
and then label the modded chip ³new².
http://gpsobsessed.com/3g-iphone-teardown-infineon-gets-built-in-gps-contrac
t-not-broadcom/
Rummaging on infineon's website for the Hammerhead.. It's a tiny RF front
end and correlator with a serial connection to the host processor. It takes
a 32kHz backup osc and a reference osc from 10-40 MHz. I doubt that there's
an output for any sort of code epoch or nav message.
>
>
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