[time-nuts] Timing or Navigation GPS Receivers (was: Turning off PPS when not enough satellites)

[Brooke Clarke]

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.
>>    
>>