Re: [time-nuts] Antenna cable delay compensation

[Azelio Boriani]

In the uBlox protocol specifications there is an antCableDelay, an
rfGroupDelay, a userConfigDelay, all are 2's complement quantities, no
bounds given in the manual.

On Tue, May 22, 2018 at 4:55 AM, Mark Sims  wrote:
> A related question is:  Do you use positive or negative numbers to set the 
> antenna cable delay value?  Again, most GPS receiver documentation does not 
> say.I think that I've only seen it explicitly mentioned in the Trimble 
> documentation and the Oscilloquartz Star-4 documentation.
>
> Also there is the question of does the receiver time message come out before 
> or after the 1PPS and what is the message offset time from the 1PPS?   Again, 
> rarely documented by the receiver manufacturer.   Lady Heather can measure 
> those (if the operating system clock is accurately set)  Heather uses the 
> message time offset to adjust the displayed time or get the audible "tick 
> clock" aligned to true time.
>
> Heather has a table of typical message offsets for the supported receivers, 
> but measuring and setting the value for your receiver/computer/serial port 
> can improve things.
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Re: [time-nuts] A Request to the List

[Poul-Henning Kamp]

In message <59219f88-52bb-d127-29de-1ea0ccc2b...@febo.com>, John Ackermann N8UR
 writes:

>It's much better to have one thoughtful post than a dozen written on the fly.

See also:

http://bikeshed.org

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] Sawtooth correction: next or previous PPS

[Poul-Henning Kamp]

In message <20180522011345.4db43406...@ip-64-139-1-69.sjc.megapath.net>, Hal Mu
rray writes:
>
>hol...@hotmail.com said:
>> One thing to look out for when messing with sawtooth messages is the
>> question of does the message come out before or after the PPS pulse...  good
>> look finding the answer in the receiver documentation... 
>
>Has anybody asked the manufacturers?

It is trivial to measure with a HP5370: Capture a series where you
measure the 1PPS against a good 10MHz and record the serial datastream.

Then offline apply the negative sawtooth and plot the result.

If you get ugly spikes at the turning points of the "hanging bridges"
you're doing it wrong.

For the UT Oncore etc. it is predictive of the next 1PPS flank.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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