[ARC5] The not-so humble BC-221/LM-xx frequency meters. - zero-beating with WWV

[Richard Knoppow]

    There is a brief history of time keeping at:
https://www.nist.gov/pml/time-and-frequency-division/popular-links/walk-through-time

     Time was determined primarily by astronomical means.
     There is a great deal of other information on the web.
     I think NBS had descriptions and papers on their early time 
standards. I have not looked but would expect them to be on the NIST site.
     WWV and other HF standard stations can be received with very high 
accuracy by time averaging over a sufficiently long period. The various 
propagation errors are averaged out.  Much more stable transmission is 
to be had on LF and VLF but averaging is still necessary. ELF is phase 
stable over the surface of the earth but I think only available from a 
couple of Navy stations. References from GPS satellites beats this and 
is much easier to use.

On 12/24/2016 12:04 PM, Arden Allen wrote:
> I'm more interested in Howard's question about frequency standards in
> general.  Just how did NBS come up with frequency standards before the
> age of atomic time standards and digital counters?
>
> Arden Allen
> KB6NAX
>


-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL