[time-nuts] Measuring speed of light or reproducing a metre

[Jim Palfreyman]

My actual application is as a quick cool demo showing what I can do with
this gear in my garage when people go "why"?

:-)



On 24 June 2013 09:22, Magnus Danielson <magnus at rubidium.dyndns.org> wrote:

> Hi Jim,
>
>
> On 06/24/2013 01:03 AM, Jim Palfreyman wrote:
>
>> Hi all,
>>
>> With a 3325B, a 5370B, and other time-nut miscellany, what's the quickest
>> way you can come up with to measure the speed of light OR reproduce the
>> metre.
>>
>> I've got some ideas, but I'd like others' thoughts.
>>
>
> Using a laser that reflects and a detector, create a resonator, such that
> the received signal is amplified and modulated on the laser.
> The delay through the circuit needs to be calibrated, but once you have
> done that, you remove it from the measured period of this oscillator, and
> the remaining time will be the flight-time. Using a TIC like the 5370B you
> can measure this period with a fairly high resolution, averaging and all.
> Recall that the flight-time will for twice the distance. This setup isn't
> perfect in many senses, but you can do it.
> The 3325B might come handy in calibration.
>
> By intentionally insert extra delay (which we assume is stable and known)
> you can reduce the range of frequency and hence phase shift variation
> needed to be calibrated, which can increase the precision to some point.
>
> This is a rough method of doing it, but it may serve your needs
> sufficiently good. I could probably hack this up with scraps lying around
> my lab, possibly lacking the optics for the laser.
>
> What is your actual application?
>
> Cheers,
> Magnus
> ______________________________**_________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/**
> mailman/listinfo/time-nuts<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts>
> and follow the instructions there.
>