[time-nuts] ...Your thoughts on the Trimble Resolution T?

James Maynard james.h.maynard at usa.net
Fri Mar 31 05:24:15 EST 2006

SAIDJACK at aol.com wrote:
> The Clock Granularity message is to be applied to the next following 1PPS  
> pulse in Motorola speak. Typically, the 1PPS is captured by a Microcontroller,  
> which can then add the granularity message data to the capture time, and thus  
> improve the measurement over the long term.

The hardware granularity message can be used to provide a hardware 
correction to the time of the next one-pulse-per-second pulse. Richard 
Hambly, who does business as CNS Systems <http://www.cnssys.com/> will 
sell you his "CNS Clock II) with a "Precise PPS" option that includes 
this hardware-corrected 1 PPS output. The $1500 price includes the M12+ 
timing receiver nicely packages, together with the hardware clock 
correction option, power supply, etc., and his SynTac32 software to 
control it from a PC.  You supply (or purchase from him) the external 
antenna with 5 volt or 3 volt low noise amplifier (LNA) and the antenna 

In recent correspondence with me, Hambly claims:
"Recent tests of the CNS Clock II with the precision PPS option shows 
short term noise of about ± 3 nsec pk-pk with drift over a 10-minute 
period, probably due to ionoshperic variations, creating an overall 
error of ± 10 nsec pk-pk (zero mean, 3.7 nsec 1-sigma) as referenced to 
an HP5065A Rubidium Standard, itself calibrated to GPS."

(I presume he's using "nsec" to mean "nanosecond" -- even though the 
standard SI symbol for the nanosecond is "ns" rather than "nsec.")

James Maynard
Salem, Oregon, USA

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