[gpsd-dev] HSPA modem/GPS receiver combo

[Wouter Verhelst]

Hi,

I've had a Lenovo X220 since slightly over a year now, and it came with
a HSPA modem built in. I've used it a fair number of times over that
year, but what I didn't realize (until about an hour or two ago) is that
it's actually a combined HSPA modem/GPS receiver. This may obviously
have something to do with the fact that it's not a GPS receiver until
the relevant bits are turned on.

A quick grep through the gpsd source code reveals that it doesn't seem
to be issuing any AT commands anywhere, so I wanted to add that myself;
but I can't actually seem to find what the best place to put them would
be.

In case this is something trivially simple for those of you more
familiar with the code than I am, turning on the relevant bits is done
like so:

AT*E2GPSCTL=1,1,1
AT*E2GPSNPD

which will then produce what (to my untrained eye) looks like an NMEA
stream on the device where this was issued. It's not possible to stop
this stream other than by closing the device file.

The E2GPSCTL command's options are used to select the mode (1 meaning
NMEA, if I understand things right; there are three other modes, but I'm
not sure what they mean); the interval between updates, in seconds
(range 0-60); and the final one is used to actually enable the GPS
receiver.

I should note that my particular device seems to ignore the timeout,
always using one-second intervals.

If this is trivial to add, I'd be happy to test patches. If it's not
trivial to add, I'd love it if someone could send me a pointer towards
some relevant documentation, so I can code it up myself and send a patch
in your general direction.

Thanks,

-- 
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the following formula:

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