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Lu:
You refer to your "WWVL clock." Think you mean WWVB. WWVL, which operated on 20/26 kHz,
was decommissioned in 1972. However, WWVB does use WWVL's antenna. More info here:
 including a note that we might get an east-coast
transmitter some day.
-- Richard Langley

Quoting Lu Abel :

>
> Frank:
>
> Not to start a controversy (especially with you!), but I'm looking at
> heavens-above.com and its display is about seven seconds slower than
> time.gov.  I suspect that while, as they claim, they have very accurate
> time-keeping on their server, they're not compensating for propagation
> delay across the Internet.
>
> I just held my WWVL clock up to the time.gov display and it looks like
> my Internet time is a tiny fraction of a second faster than my clock.
> Mis-estimate of the delay to my computer by time.gov, or a display lag
> (ala Doug's Trimble) on the part of my
> $5.00-on-sale-at-the-local-electronics-superstore clock??
>
> Lu
>
> frankreed@HistoricalAtlas.com wrote:
> > Douglas Denny, you wrote:
> > "I can understand too that modern GPS engines are going to calculate faster and so
> give less delay - but nevertheless there is no excuse whatever that the display time
> can, with no effort needed by the designer, be _exact_ and displayed as such or
> flagged as U/S until correct.  It is really rather silly to have a piece of kit which
> receives signals of time to within a few nanoseconds, knows it,  and cannot display
> it accurately"
> >
> > But this is just a market demand issue (and market demand drives product
> specifications, right?). The vast majority of GPS users are looking for position
> information primarily, and the time from the device is just a bonus. Very few GPS
> users require time accurate to the nearest five seconds, let alone the nearest tenth
> of a second. Who would use that information in a handheld GPS unit or any unit
> designed fundamentally for position-finding? Of course, there are entirely different
> market segments out there, like mobile phone companies, for whom the exact time is
> actually the most important product in the GPS signal. It all comes down to demand. I
> agree that it's ironic that the exact time is in there, hidden away somewhere, but I
> don't agree that it's "silly" we can't see it. It's like my previous cell phone which
> had a GPS receiver and knew its position accurately but had no way to display it
> (this was a marketing choice by the manufacturer and the service provider). But it
> DID have extremely exact time displayed --accurate to the nearest tenth of a second
> quite reliably. This was derived from the cell towers' clocks apparently, and
> presumably the towers got it from specialty GPS hardware.
> >
> > On the other topic in this thread, Internet time can be very good. One of my
> favorite older web sites, the satellite tracking site at www.heavens-above.com,
> recently added a little tool that provides properly synchronized time accurate to
> "better than" one tenth of a second. I tested it from my PC against WWV just tonight,
> and it seemed to be that accurate. Then I tested the same web page from the web
> browser in my current smartphone (two years old so therefore "a dinosaur"). That same
> tool in the phone browser could not keep up. The initial time was about right, but
> the ticking seconds after that were in some kind of time warp and fell thirty seconds
> behind after one minute. The phone's internal time (not from the Internet) can be up
> to fifteen seconds off which is not good enough for celestial navigation experiments,
> but certainly good enough for any practical tasks I do in my day.
> >
> > -FER
> >
> >
> >
> >
> > >
> >
>
>
> >
>


===============================================================================
 Richard B. Langley                            E-mail: lang@unb.ca
 Geodetic Research Laboratory                  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics Engineering    Phone:    +1 506 453-5142
 University of New Brunswick                   Fax:      +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
     Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===============================================================================



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