wrote in message
...

Cool - Better Living Through Mathematics ;-)

I like that. Lots of "throbbing DSPs" in a DTT receiver, to use a phrase
coined by an acquaintance of mine, who posts here occasionally.

IFFT for the COFDM demod, soft-decision Viterbi and Reed-solomon FEC
decoding & then MPEG decoding. Try doing all that with valves (he said,
being half-way through reading Gerogina Ferry's book about LEO).

At those sorts of times (7us), presumably the intention is to provide
robustness to "near" reflections, e.g. off big buildings close by -

Yes.

since, as we're taught by the Damestress Grace Hopper herself, a foot
is a nanosecond,

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?

them newfangled keel-o-meters. So it's good for multipath suppression
for different signal paths from the same transmitter; not designed at
all, presumably, for interference between competing transmitters

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?

--
Andy