[time-nuts] NIST's WWVB phase modulation format paper from PTTI 2011

[John Ackermann N8UR]

Attached are three images of phase data that I captured during and after 
the test.  These are the 1PPS output from a Spectracom 8170 time code 
receiver compared to the PPS from an Rb standard (with linear frequency 
offset removed).

The Spectracom PPS is derived from a 10 MHz crystal that is fairly 
tightly phase locked to the WWVB carrier.  It's not quite the same as a 
tracking receiver, but you can see from the "after" that it tracks the 
phase ID quite closely.

First image is the whole 72 hours showing the last day or so of the test 
period and the return to normal operation.

Second image is a zoom in of the new modulation as tracked by the receiver.

Third image is a zoom in of the old modulation over the hourly 45 degree 
phase shift ID.

John




J. Forster said the following on 03/14/2012 05:21 PM:
> Has anybody looked at the impact of the periodic phase reversals of BPSK
> on the loop of phase-tracking receivers, like the Fluke or the HP 117A?
>
> NIST does claim backward compatability for time. But what about time
> interval?
>
> I know you can extract the carries from BPSK with a Costas Loop (which
> essentially squares the signal and uses the second harmonic) but the
> existing, installed hardware does not do this.
>
> If I'm right, that's another broken egg in the frequency reference basket.
>
> Best,
>
> -John
>
> ================
>
>
>> Here is a copy of the paper NIST co-authored describing the new WWVB phase
>> modulation format:
>> 	http://jks.com/wwvb.pdf  (2MB PDF)
>>
>> John Lowe from NIST said I could redistribute it to the list. It will be
>> available on the NIST website sometime in April once the official PTTI
>> 2011 proceedings are published. When that happens I'll remove my link
>> above and you can find the paper here:
>> 	http://tf.boulder.nist.gov/general/publications.htm  (search for Bin
>> Number "2591")
>>
>> Also of interest, a company contracted to help with the development will
>> have silicon (and patents) at some point:
>> 	http://www.xtendwave.com/xtendwave-awarded-grant-for-atomic-clock-enhancements.html
>> 	http://www.xtendwave.com/atomictimekeeping.html
>>
>>
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>
>
>
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