Re: How to get raw data from gpsd?

[Gary E. Miller]

Yo 张延涛!

On Wed, 10 Apr 2024 21:12:37 +0800
张延涛 <zh6tao@gmail.com> wrote:

> I regret to inform you that after discussing with the chip
> manufacturer, it appears that the raw data format of ALLYSTAR is
> considered confidential in commercial terms and is not available for
> public access. Therefore, we are unable to obtain any related
> protocol manuals.

I already have the 2.3.6 version manual, and most of the protocol they
just copied from u-blox.  Their chip distributors have posted that
manual online.  Not much of a secret.  At least for the "older" parts.

Would you like me to send you my copies of the manuals?

When I get a newer manual I can add the newer parts.

> What is known is that the binary data outputted by ALLYSTAR begins
> with 0xF1D9 and ends with 0x0D0A. Hence, gpsd can filter out the
> binary data of ALLYSTAR according to this rule.

I wish it were that easy, but it is not.  Since I have the 2.3.6 doc, I
have figured out the protocol, a sloppy copy of the ubx protocol, and
I have programmed gpsd to handle it.  Untested.

> Furthermore, through several experiments, I've found that if ALLYSTAR
> outputs an excessive amount of raw data too quickly (approximately
> 30KB of hexadecimal data per second), gpsd tends to drop some bytes
> of data approximately every 2 minutes and 30 seconds.

Yeah, 30KBps does not fit in a 115.2Kbps pipe.  Faster spped is a part
of the u-blox protocol that they neglected to copy.

I just received in the mail a TAU1202 module, and am using that to
debug the new code in gpsd.  The gpsd support for the TAU1202 should
be finished this week, and in git head.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        gem@rellim.com  Tel:+1 541 382 8588

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    "If you can't measure it, you can't improve it." - Lord Kelvin

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