Message-ID: <25798.200103261700@gemini>
From: "James Moritz" <j.r.moritz@herts.ac.uk>
Organization: University of Hertfordshire
To: rsgb_lf_group@blacksheep.org
Date: Mon, 26 Mar 2001 18:05:15 +0000
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Subject: Re: LF: RE: WOLF (BPSK) modulation continuous phase modulation.
In-reply-to: <3.0.1.16.20010326144713.21b765b2@mail.cc.kuleuven.ac.be>
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Dear Rik, LF Group,

Another way of looking at this modulation method is that the high Q 
tuned circuit acts as a narrow filter which removes the unwanted 
sidebands of your "rude" BPSK - the signal will certainly be 
amplitude modulated at the output of the tuned circuit; in fact it will 
look very similar to the "ideal" envelope-modulated BPSK signal. 
This is effectively another way of generating the BPSK signal, 
analagous to generating SSB by the filter method. But 
unfortunately, any clipping or AGC will distort the amplitude 
envelope, which in turn will re-introduce unwanted sidebands. 

Of course, if the filter was placed at the transmitter output, this 
criticism would not apply. But although it is probably possible, 
producing an antenna tuning network with a loaded Q of 700 would 
be quite difficult.

Cheers, Jim Moritz
73 de M0BMU