Best practices question

Gary E. Miller gem at rellim.com
Thu Jun 27 17:28:00 UTC 2019


Yo Hal!

On Wed, 26 Jun 2019 22:31:37 -0700
Hal Murray <hmurray at megapathdsl.net> wrote:

> gem at rellim.com said:
> > That "if the path delay is removed" is important.  I'm about 4
> > milli Seconds from Fort Collins.  Which varies by atmospheric
> > condidions.  Not as good as an NTP connection to a regional Stratum
> > 1 server.  
> 
> Do you have any data on the atmospheric delays?

Not at hand.  But I remember listening to distant radio stations and
have the signal sound light a dopler shift coming and going.
 
> I thought the ground wave was supposed to be stable.

Except the ground wave may be interfered with.

> > Now that my time server gets time from GPS, BeiDou, Galileo and
> > GLONASS I'm not so worried about a GPS outage.  
> 
> Do you have any data from working without GPS?

Yes.  GPS is best, but the rest are close by.  u-blox 9 even gives
you error estimates of the difference between systems.

> I also worry about common mode problems.  Something like a big solar
> flare could take them all out.

Yeah.  ALL.

> > eLORAN is the proper replacement for WWVB.   
> 
> Too bad Congress didn't agree.  The funding for LORAN in the US was
> pulled several years ago.

LORAN-C was pulled.  I know because I have a perfectly good LORAN-C
receiver here.  eLORAN is next-gen, and funded.

https://www.gps.gov/policy/legislation/loran-c/

    On December 4, 2018, President Trump signed the Frank LoBiondo Coast
    Guard Authorization Act of 2018 (P.L. 115-282), which includes as
    Section 514 the National Timing Resilience and Security Act of 2018.

    The act amends Title 49 of the U.S. Code to include the following
    language:  View text at congress.gov

	§ 312. Alternative timing system
        (a) In General.—Subject to the availability of appropriations,
        the Secretary of Transportation shall provide for the
        establishment, sustainment, and operation of a land-based,
        resilient, and reliable alternative timing system—

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at rellim.com  Tel:+1 541 382 8588

	    Veritas liberabit vos. -- Quid est veritas?
    "If you can’t measure it, you can’t improve it." - Lord Kelvin
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