In uk.d-i-y, Andy Wade wrote:

Interesting - I think I first heard "one foot per ns" from somebody at
Mullard; I didn't know there was connection with Ms Hopper. Didn't she
invent the concept of the compiler?

I don't think she's the one we thank for compilers: early FORTRAN beat
her to that punch. But we do have her to thank for COBOL (I presume you
know the one about its Stroustrup-analogue object-oriented follow-on,
ADD ONE TO COBOL. ?) And the story goes she used to enliven her public
talks by handing out 'nanoseconds' - one-foot lengths of copper wire.

That's how its currently used for UK DTT. Another application is the
'single frequency network' concept used for the national DAB multiplexes.
This depends on having precisely synchronised transmitters (done using GPS
for the timing, I think) all radiating the same stream, and, obviously, a
longer guard interval -- 246us for Mode 1 DAB (the mode used on Band III).
From the receiver's point of view there's no difference between a reflected
signal and one from another synchronous TX. Clever innit?

You've answered the follow-up question I stopped myself from asking! Couldn't
immediately see how the DAB network would cope given single-frequency
transmission with the maths working out as for Freeview, but wasn't
curious enough to either think through the obvious answer of "much longer
guard interval", or to ask. And here it comes, unasked for but no less
gratefully received ;-)

Cheers, Stefek