I am not sure how uBlox does this, but the spec for the M8 series sounds to me that they are doing real GNSS measurements not just DR but I may be wrong.
UBX-CFG-RATE
...
This message allows the user to alter the rate at which navigation solutions (and
the measurements that they depend on) are generated by the receiver. The
calculation of the navigation solution will always be aligned to the top of a
second zero (first second of the week) of the configured reference time system.
...
• Each measurement triggers the measurements generation and, if available,
raw data output
• The update rate has a direct influence on the power consumption. The more
fixes that are required, the more CPU power and communication resources are
required.
...
measRate -> The elapsed time between GNSS
measurements, which defines the rate, e.
g. 100 ms => 10 Hz, 1000 ms => 1 Hz,
10000 ms => 0.1 Hz.
BR,
Jürgen
Am Mo., 5. Sept. 2022 um 21:43 Uhr schrieb Gary E. Miller <
gem@rellim.com>:
Yo Jürgen!
On Mon, 5 Sep 2022 21:04:45 +0200
Jürgen Hausladen <hausladen.j@gmail.com> wrote:
> > > Not a surprise. Tey gpsd in the standard configuration. If that
> > > fails then we could work on some patches.
>
> I started using the JSON mode with NTPd due to an issue we had back a
> couple of years ago, where it happened, that the system time
> (sometimes after days or even a week) suddenly started drifting away
> in shared memory mode even in the range of seconds.
That can happen when you forget the "preferred" keyword in ntp.conf and
the PPS gets outvoted.
> > > 10Hz mode is a lie anyway, little
> > > need to use it.
>
> I actually don't need the 10Hz update rate for the time sync, but when
> using the device also for location based event triggering in a
> vehicle. What do you actually mean by 10Hz mode is a lie anyway?
Almost no receiver calculates fixes faster than 1Hz. In almost all
cases, sub second PVT is Dead Reckoning (DR). Which can be very
misleading.
> The
> GPS module I am using is at least from its specs capable of running
> with 10Hz.
"Running", yes. But complete fixes? Very unlikely.
The only way to get good sub-Hz fixes is with a wheel tick sensor.
RGDS
GARY
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