[time-nuts] Timing or Navigation GPS Receivers (was: Turning off PPS when not enough satellites)
Brooke Clarke
brooke at pacific.net
Tue Aug 1 19:49:54 UTC 2006
Hi Ulrich:
It's interesting that the now in development carrier phase GPS time
transfer method that might offer 1,000 times lower uncertanity is based
on the Ashtech Z12 surveying receiver, not a timing specific GPS receiver.
http://scholar.google.com/scholar?q=Ashtech%20Z12%20carrier%20phase%20GPS%20time%20transfer&hl=en&lr=&oi=scholart
Have Fun,
Brooke Clarke
--
w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
http://www.precisionclock.com
Ulrich Bangert wrote:
>Poul-Henning did already give the answer. However i am not very happy
>with the formulation
>
>
>
>>In other words, it has nothing to do with the receiver, it's
>>about what you ask it to do.
>>
>>
>
>because
>
>a) I never saw a navigation receiver featuring a "position hold" mode
>
>b) I never saw a timing receiver featuring a "navigate forever" mode.
>Everything that i had in my hands had a "automatic site survey" mode
>after which it would return to "position hold". That's why i think the
>formulation that it depends on the receiver's primary purpose is not
>that wrong!
>
>Regards
>Ulrich Bangert
>
>
>
>>-----Ursprüngliche Nachricht-----
>>Von: time-nuts-bounces at febo.com
>>[mailto:time-nuts-bounces at febo.com] Im Auftrag von Poul-Henning Kamp
>>Gesendet: Dienstag, 1. August 2006 12:28
>>An: bg at lysator.liu.se; Discussion of precise time and
>>frequency measurement
>>Betreff: Re: [time-nuts] Turning off PPS when not enough satellites
>>
>>
>>In message
>><63849.212.181.149.145.1154423937.squirrel at webmail.lysator.liu.se>,
>>bg at lysator.liu.se writes:
>>
>>
>>>On Tue, August 1, 2006 10:56, Ulrich Bangert said:
>>>
>>>
>>>
>>>>Note that any gps receiver can not be really good for
>>>>timing and navigation at the same time, so all navigation
>>>>
>>>>
>>receivers
>>
>>
>>>>make bad timing receivers.
>>>>
>>>>
>>>I am interested in your arguments for the above statement. Please
>>>elaborate!
>>>
>>>
>>The above statement should probably be read as:
>>
>>"If you solve for both position and time you get worse time
>>than if you hold the position constant and solve only for time"
>>
>>In other words, it has nothing to do with the receiver, it's
>>about what you ask it to do.
>>
>>Not all receivers can do "position hold" mode of course.
>>
>>--
>>Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
>>phk at 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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