[time-nuts] Next step up from basic GPS/PPS timekeeping
Bob Camp
kb8tq at n1k.org
Wed Feb 24 19:36:06 EST 2016
Hi
The tick is a burst of audio at a fairly low frequency. You are going to need pretty
good conditions to get 0.1 ms. The fade process over much of the day will spread
that out a *lot*.
Bob
> On Feb 24, 2016, at 5:11 PM, Tim Shoppa <tshoppa at gmail.com> wrote:
>
> Hal -
> In my experience over more than a decade, the ntpd WWV audio refclock has
> jitter circa 0.1ms.
>
> This is not nanosecond-time-nut PPS territory. But it is more than good
> enough for WAN ntpd.
>
> I use a Ten-Tec RX-320 as a cheap frequency-agile receiver for WWV. In
> between 5MHz/10MHz/15MHz usually one or two bands are open from me to
> Colorado.
>
> On the subject of WWVB - if you are near Colorado then you can have 24x7
> reachability, day or night. For me on the east coast, WWVB 60kHz is
> reliable in darkness but not in daylight.
>
> Tim.
>
> On Wed, Feb 24, 2016 at 1:56 PM, Hal Murray <hmurray at megapathdsl.net> wrote:
>
>>
>> tshoppa at gmail.com said:
>>> My opinion if you want to serve reliable time through a longer GPS
>> outage:
>>> add a WWV or WWVB based radio clock. e.g. a shortwave radio and https://
>>> www.eecis.udel.edu/~mills/ntp/html/drivers/driver36.html
>>
>> Do you have any graphs comparing WWV or WWVB to GPS when your GPS is
>> working
>> correctly?
>>
>> When I run out of other things on my list, I'd like to collect that data.
>> What receivers do people recommend?
>>
>> I have one of the low cost WWVB receiver modules but I never got any useful
>> data out of it. Maybe it's time to try again. It might work better on the
>> end of a long cable to get it away from all the EMI in my office.
>>
>>
>> --
>> These are my opinions. I hate spam.
>>
>>
>>
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