Re: How to get raw data from gpsd?

[Gary E. Miller]

Yo 张延涛!

On Mon, 22 Apr 2024 20:04:12 +0800
张延涛 <zh6tao@gmail.com> wrote:

> I just submitted a PR
> <https://gitlab.com/gpsd/gpsd/-/merge_requests/405> regarding how to
> filter binary data sent by ALLYSTAR. When using the ALLYSTAR chip,
> filtering out binary data first can alleviate the parsing pressure on
> gpsd (perhaps filtering out known garbage data first can reduce time
> complexity), thus addressing the issue of missing bytes in raw data.

That's not gonna work.  Comments in the MR.

> Additionally, I have a small question to consult about. Why do I get
> so many 0 values printed within one second when using
> `while(1){gps_read();}` to obtain satellites_visible?

Because not all messages you read contain satellite data.  And the sample
that uo sent previsouly had no datellite data at all.  This is a common
mistake, have you read the gpsd client examples?

https://gpsd.io/gpsd-client-example-code.html

> Moreover, the
> value of satellites_visible dynamically increases within one second.

Yes.  Of course.  The ALLYSTAR chips talks to gpsd over a serial link, one
satellite at a time, and gpsd has to accumualte that data.

> My understanding is that this dynamic increase process is gpsd
> collecting statistical data.

Uh, no.

> Could we design the `gps_read()`
> interface to only report statistical results without reporting the
> statistical process?

It is the job of you client to take what it needs and ignore the reset from
the JSON feed.

Before we go further:

I have asked many times: what version gpsd are you using?

For me to see what you see, I need a good sample of the raw data you see.
YOur last serial capture was corrupted.

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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