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Re: Geosynchronous Satellites



On Tue, Dec 26, 2000 at 09:46:02PM -0600, Jon Ogden wrote:
> on 12/26/00 5:54 PM, Hamish Moffatt at hamish@cloud.net.au wrote:
> 
> > Are there other forms of amplitude modulation for digital signals
> > besides QRM? I'd think those modes would be at a disadvantage compared
> > to the frequency/phase shifting modes with constant envelope.
> 
> I hope you meant QAM not QRM!  :-)

Oops. Slip of the fingers.

> Let's see I know there is a few: OOK (on-off keying basically a form of CW
> but it could possibly count as a constant envelope form of modulation), I

CW is OOK (aka ASK).

> think BPSK can do be done in AM, PSK can (as we see on HF).  I'll defer to

PSK/BPSK is phase shift keying, which should be independent of amplitude.
I don't understand your comment about HF -- PSK31 is phase shift keying,
and it is usually transmitted on HF using the SSB mode on the radio,
but that doesn't make it amplitude modulation any more than RTTY
transmitted that way is (it's still FSK, frequency modulation).


Hamish
-- 
Hamish Moffatt VK3SB <hamish@debian.org> <hamish@cloud.net.au>
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