[time-nuts] Re: Is there a term for the reverse/inverse of harmonic?

[Jim Lux]

 
An example of this is deep space transponders for ranging.

The transmitted frequency is some ratio of integers of the received frequency (880/749 for X-band) - But there may not be anything in the device at the common value (called f0 in most of the papers talking about this) - For example, a lot of transponders generate the output signal as 220 * refosc and the LO for the receiver as 187*refosc (where refosc is something around 40 MHz).


On Mon, 28 Apr 2025 13:21:26 +0200, Magnus Danielson via time-nuts <time-nuts at lists.febo.com> wrote:

Hi,

A reflection. You might not have the fundamental accessable, but it may
be relevant indirectly. Two frequencies may be say 2/5 or 3/5 of some
other frequency, thus you do 2 or 3 cycles while the higher does 5
cycles. Thus they can be locked and have a fixed relationship and that's
where fractional frequency becomes relevant without having a fundamental
or subtone.

Cheers,
Magnus

On 2025-04-28 12:36, Hal Murray via time-nuts wrote:
> Thanks for all the replies.
>
>
> Tom asked me to take care of the backlog -- that is let anything great
> through but don't flood our mailboxes.
>
> I just dropped a dozen or so. (and fatfingered one that went through,
> apologies)
>
> Here is a summary of the ones I dropped
> There were 10 mentions of subharmonic.
> There were 3 mentions of fundamental
> There was one suggestion of undertone
> and another of fractional harmonic or fractional frequency
>
>
> On Wikipedia, subharmonic redirects to "Undertone series" which begins "In
> music...".
>
> Meriam-Webster has an entry for subharmonic.
> : a component of a periodic wave having a frequency that is an integral
> submultiple of the fundamental frequency
>
>
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