Curiosity prevails:<br><br>I do see a few benefits to a device which is just a GPS radio, like what Ian has stated. Would their be any legal ramifications to a reverse-engineered open source binary interpreter for the GPS radio? I saw a few people mention government concerns with having access to a very accurate GPS device, but what about Global Locate's license agreement (if any) by using their hardware? I think a "GPS radio" would make an excellent open source project; allowing access to the specifics of GPS (theory) not available with closed firmware.
<br><br>I wouldn't mind working on this project.<br><br>-Kyle<br><br><div class="gmail_quote">On Nov 29, 2007 9:46 PM, Ian Stirling <<a href="mailto:OpenMoko@mauve.plus.com">OpenMoko@mauve.plus.com</a>> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div class="Ih2E3d">Doug Sutherland wrote:<br>> Mikko wrote:<br>>> 2) Yes, it can make sense not to have a bazillion CPUs on board from
<br>>> various perspectives.<br>><br>> I evaluated no less than 25 different GPS modules some years ago<br>> and compared them in all important aspects. Every single one had<br>> a microcontroller onboard. I do not agree that it makes any sense
<br>> at all not to choose one of these types. They are down to the size<br>> of a thumbnail almost. Is the microcontroller a CPU, technically<br>> yes, but it's part of the receiver, and you want to do all this fancy
<br>> GUI and not suck the life of the battery from ARM9 usage. It is<br>> a good thing they ditched that GPS. It is now standard that any<br>> GPS module does have a microcontroller inside, most commonly<br>> some variant of ARM7, super low power, you never deal with
<br>> any firmware.<br><br></div>(sorry for the late response)<br><br>To clarify why it might be nice - yes there are simplicity benefits<br>from just using a GPS with a NMEA output (or at least with that as an<br>option)
<br><br>If the existing hardware had an open-source driver (there was some<br>progress towards such, but this has stalled since it was announced it<br>would not be used in GTA02) then many of these objections go away.<br>
<br>The following is based on preliminary work that has not been completed,<br>and due to the lack of work on the current GPS may never be.<br><br>The device is basically only a software radio, that does the absolute<br>minimum to enable the host to avoid having to do hard-real time stuff,
<br>115200 baud serial is just fine.<br>As I understand it, the following things are possible, which are<br>difficult to do with 'normal' chipsets.<br><br>Wakeup once every 3 minutes for 1s, to maintain lock on satellites,
<br>keeping a reasonable (say 50m) position accuracy, with the GPS totally<br>off in the interim. This (with the mobile phone part off) uses a very<br>small amount of power, enough to track for around 8 months.<br><br>Logging all parameters of the signal that the chip measures in hardware,
<br> so that the track can be post-processed for better accuracy.<br><br>The option of delaying the output of the signal by 10s+, and being able<br>to smooth the output based on the 'future' movement, not just the past.
<br>(this can dramatically improve tracks round sharp corners)<br><br>Being able to feed in information from the accelerometers to go into the<br>position solution. (this is mainly useful in cars - the accels give you<br>
good turn rate info)<br><br>Using even 'failed' GPS satellites as position sources, with the aid of<br> AGPS (however, this is unlikely to be of use unless the GPS system<br>stops being maintained)<br><br>Easy tradeoffs between output noise and update frequency - few devices
<br>support updates faster than 1Hz.<br><br>User-provided AGPS correction information.<br><div><div></div><div class="Wj3C7c"><br><br>_______________________________________________<br>OpenMoko community mailing list<br><a href="mailto:community@lists.openmoko.org">
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