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OK Andy,
I was thinking more in terms of generating
the pulse using 'audio' and not by hard keying .. but the 'area under
the curve' looks a little 'thin' ..pity .. the rest of
the system could be 'constructed' using a audio editor .and sent via a ssb
tx with alc 'off' .. how accurate is the start time requirements ?
tnx- G ..
Sent: Friday, March 06, 2009 8:13 PM
Subject: Re: LF: Multi-function beacon
Not strictly -
Look at it in th efreqeuncy domain. A 500us pulse has its first zero
at 2000/pi = 637Hz, so most of the energy is within 1300Hz bandwidth, and a
substantial part will pass though the Rx filter. It will be extended in
time and flattenned, but the detection algorithm finds the peak, in effect
applying an inverse transform of the SSB filter.
Nb the pulse width , 500uS .. that's
a bit sharp for a ssb filter , only 1.5 cycles at 3 Khz ....
?
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