Tobias
Yes that's the other way I suppose , harmonic generator and some filter
.the ssb tx will do the rest ( we hope)...may be a email to Patric
, multi psk , he did make a test version some time ago , with a wider
tone spacing
Those station with logic divider chain driving a class e/d amp
..only need to square up 1.9 MHz with a x4 tone spacing ,feed it to
the chain and the output is the data mode on 477 , with the x1
spacing .. simple !
Be nice if there was a app that looked like a soundcard , could
select as the tx card .......but its a simple way to run data on 477
, the mfsk mode's , proved a lot better than psk in the past and do
not need a linear tx/rx path
250 Hz b/w mfsk or the ros-mf mode 100hz all could be used ,
(olivia needs a linear tx/rx)
73-G.
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From: "Tobias DG3LV" <[email protected]>
Sent: Monday, February 25, 2013 1:21 PM
To: "Graham" <[email protected]>; <[email protected]>
Subject: Re: LF: DSP app to multiply tone by 4 ?
Hi Graham !
An alternative would be to use hardware like two cascaded active
rectifiers using OP-amps to get the frequency x 4. As those digital modes
do not need linear sine waves on transmit, it is no problem using even
square-wave-tones for modulation. Maybe some filtering is necessary to not
overload the AF-input of the transmitter.
This circuit could be realised as an inline-PCB between soundcard output
and TRX input.
Certainly such a "solution" is not really "elegant", but should do the
trick.
73 de dg3lv Tobias
Am 25.02.2013 13:24, schrieb Graham:
DSP app to multiply tone by 4 ?
One thing that one of the PA (Dutch PA) stations spotted , is the 477
band is a handy divide by 4 from 1.9MHz .. and if you use two
flip-flops , you can divide from 1.9 to 477
Setting the rtty shift x 4 in fl digi 340 HZ , then gives 85 Hz at 477
A problem with the multi tone modes , unless its possible to write a
'dsp'
app , that multiplies the tones by 4 , single tone fixed amplitude in
real-time or slightly after ,
That would open up all the (non linear) modes
to 477 , X2 for 'logic' drive amps, X2 drive, and X4 for conventional on
frequency amps ?
Q Is this a possibility ?
Could something be coded , that either looked like a sound card
, or took audio in , and outputted a multiplied frequency by 2 or
4
Could have delay as long as the delay was fixed ?
G..
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