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Re: LF: Bandwidths/Modes

To: [email protected]
Subject: Re: LF: Bandwidths/Modes
From: "Vernall" <[email protected]>
Date: Sat, 14 Apr 2001 08:41:26 +1200
References: <[email protected]>
Reply-to: [email protected]
Sender: <[email protected]>

Very interesting on the three types of spectra:

So far I 'played' with 3 types of modulation : real BPSK, PSK (amplitudes
enveloped) and what I call 'soft' PSK (gradual phase transitions instead
brute phase jumps).
The spectra (and and block diagram of the modulator) can be found at :

It confirms that :
- BPSK is far too wide to be used with high power on 136kHz (unless you
live in the middle of nowhere or you just don't care about others)
- that PSK has the best (most narrow) bandwidth
- that 'soft' PSK may have some potential as a class-D suitable mode with
an acceptable bandwidth.
I think it would be useful to include a 4th spectra for CW "on-off keying"
as there is nearly a century of experience with sharing frequencies where
there are finite key clicks.  One criteria is for BPSK bandwidth to be no
more than a same PEP and same data rate CW emission.

73, Bob

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