RE: Wire Length

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Bill Fuller" <bill@xxxxxxxxxxx>


I really don't think Tesla "intended" to generate spurious frequencies
(spread spectrum in this context). A spark gap generates an impulse that in
turn generates a huge number of frequency components. The only "useful"
frequency is the resonant frequency of the coil. It's also the most dominant
generated by far. Spread spectrum in practice has all the frequency
components at roughly the same level.

If Tesla could of generated pure sine wave frequencies, he would have used
that method.

Bill

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Wednesday, January 10, 2007 9:37 PM
To: tesla@xxxxxxxxxx
Subject: Re: Wire Length

Original poster: Ed Phillips <evp@xxxxxxxxxxx>


Wikipedia defines spread spectrum as, "methods in which energy
generated at a single frequency is deliberately spread over a wide
band of frequencies."

This matches up fairly well with what Tesla was doing in 1898.  The
"single frequency" is that at which the primary circuit vibrates when
energized."

    The Wikipedia definition is incomplete in that it implies that
the only way to generate a spread spectrum signal is to modulate a
single frequency one.  That's not necessarily true as there are other
ways to generate a "wide band of frequencies" - filtering and
modulating of a random noise signal is example with which I'm familiar

    Tesla was using a narrow band transmitter and receiver for each
of his frequencies and correlating the outputs to decide whether or
not a [two tone] signal was present.  Two (or several for that
matter) relatively narrow band signals don't equal a "wide band of
frequencies".

Ed