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