DomainKey-Signature: a=rsa-sha1; c=nofws;
        d=gmail.com; s=gamma;
        h=mime-version:in-reply-to:references:date:message-id:subject:from:to
         :content-type;
        b=qHDgw4pscGhkuFByZlcwaE+9HQMbBb0ix+ZZhCiJ+CFSYKhGpVoYoDs//jsOe+5lO+
         sWd3FPt6HhQe5ofS7WRK5m8QwCEsEzfs2+Lvymsuo9lbfOhugUCAmk4Q02Ho0HewkNA1
         cUkLMj4BfzalSarAjed96+LftwyiQ3q6wpDKg=
MIME-Version: 1.0
In-Reply-To: <BANLkTik1nVPsUHhN=OM=2Vco5X=_7=SQoA@mail.gmail.com>
References: <4DAF42C1.8010401@telus.net>
	<BANLkTik1nVPsUHhN=OM=2Vco5X=_7=SQoA@mail.gmail.com>
Date: Wed, 20 Apr 2011 22:09:34 +0100
Message-ID: <BANLkTimGqczfpMfW4RYhz4WKeoZ0iye+bw@mail.gmail.com>
From: Andy Talbot <andy.g4jnt@gmail.com>
To: rsgb_lf_group@blacksheep.org
DomainKey-Status: good (testing) 
Subject: Re: LF: MSK with a Class D transmitter...?
Content-Type: multipart/alternative; boundary=005045015a6ba5a03004a1600afb
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org


--005045015a6ba5a03004a1600afb
Content-Type: text/plain; charset=ISO-8859-1

Bin too quick to type..
NOt thinking straight...

You need to the upconvert either the resulting doubled audio tone by twice
the RF carrier, or upconvert first and double the final RF.  Same ideas for
frequency doubling can be used.

See http://www.g4jnt.com/LFUpconv.pdf  for a direct from audio upconverter.

Must fully check before hitting SEND !

Andy
G4JNT

On 20 April 2011 21:50, Andy Talbot <andy.g4jnt@gmail.com> wrote:

> I assume you are genrating the MSK from soundcard output, in which case two
> options come to mind:
>
> 1)  Double the frequency.  Full wave rectify the audio sinusoid, pass the
> AC part of the result into a comparator and into the divider.
> Alternatively, as the signal bandwidth is probably quite low, square up the
> audio to start with, feed into one inpiut of an XOR gate.  Delay the
> waveform by 90 deg and feed this into the othe side of the XOR.    Output of
> XOR to divider as before
>
> 2)   Remove the  divide by two, and replace with an inverter / buffer pair
> to generate the out of phase drive signals.   The  input now needs to be
> close to a 1:1 squarwave at output frequency.   Pass the soundcard audio
> into a comparator and make sure it gives a 50% duty cycles.
>
>
> Andy
> www.g4jnt.com
>
> ps.
> or 3)    Convince the software author the S/W needs modifying to give a 2.F
> output
>
>
> On 20 April 2011 21:32, Scott Tilley <sthed475@telus.net> wrote:
>
>> Hi All
>>
>> I wonder if someone can explain to me how to feed an MSK signal into a
>> typical Class D transmitter?
>>
>> I mean by typical that the TX has a 4013 type /2 system feeding two FET
>> drivers to drive FETs in a push-pull configuration.
>>
>> If I understand correctly due to the fact MSK does not have amplitude
>> component to its signal that a non-linear transmitter can be used.
>>
>> So, how do you do this with a Class-D TX as often used in LF/VLF?
>>
>> Thanks,
>> Scott
>> VE7TIL
>>
>>
>>
>>
>

--005045015a6ba5a03004a1600afb
Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable

<div>Bin too quick to type..</div>
<div>NOt thinking straight...</div>
<div>=A0</div>
<div>You need to the upconvert either the resulting doubled audio tone by=
 twice the RF carrier, or upconvert first and double the final RF.=A0 Same=
 ideas for frequency doubling can be used.</div>
<div>=A0</div>
<div>See <a href=3D"http://www.g4jnt.com/LFUpconv.pdf">http://www.g4jnt.co=
m/LFUpconv.pdf</a>=A0 for a direct from audio upconverter.</div>
<div>=A0</div>
<div>Must fully check before hitting SEND !</div>
<div>=A0</div>
<div>Andy</div>
<div>G4JNT<br><br></div>
<div class=3D"gmail_quote">On 20 April 2011 21:50, Andy Talbot <span dir=
=3D"ltr">&lt;<a href=3D"mailto:andy.g4jnt@gmail.com">andy.g4jnt@gmail.com<=
/a>&gt;</span> wrote:<br>
<blockquote style=3D"BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8e=
x; PADDING-LEFT: 1ex" class=3D"gmail_quote">
<div>I assume you are genrating the MSK=A0from soundcard output, in which=
 case two options come to mind:</div>
<div>=A0</div>
<div>1)=A0 Double the frequency.=A0 Full wave rectify the audio sinusoid,=
 pass the AC part of the result into a comparator and into=A0the divider.=
=A0 Alternatively,=A0as the signal bandwidth is probably quite low, square=
 up the audio to start with, feed into one inpiut of an XOR gate.=A0 Delay=
 the waveform by 90 deg and feed this into the othe side of the XOR.=A0=A0=
=A0 Output of XOR to divider as before</div>

<div>=A0</div>
<div>2)=A0=A0 Remove the=A0 divide by two, and replace with an inverter /=
 buffer pair to generate the out of phase drive signals.=A0=A0 The=A0=A0in=
put now needs to be close to a 1:1 squarwave at output frequency.=A0=A0 Pa=
ss the soundcard audio into a comparator and make sure it gives a 50% duty=
 cycles.</div>

<div>=A0</div>
<div>=A0</div>
<div>Andy</div>
<div><a href=3D"http://www.g4jnt.com/" target=3D"_blank">www.g4jnt.com</a>=
</div>
<div>=A0</div>
<div>ps.=20
<div>or 3)=A0=A0=A0 Convince the software author the S/W needs modifying=
 to give a 2.F output</div></div>
<div>
<div></div>
<div class=3D"h5">
<div>=A0</div>
<div>=A0</div>
<div class=3D"gmail_quote">On 20 April 2011 21:32, Scott Tilley <span dir=
=3D"ltr">&lt;<a href=3D"mailto:sthed475@telus.net" target=3D"_blank">sthed=
475@telus.net</a>&gt;</span> wrote:<br>
<blockquote style=3D"BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8e=
x; PADDING-LEFT: 1ex" class=3D"gmail_quote">Hi All<br><br>I wonder if some=
one can explain to me how to feed an MSK signal into a typical Class D tra=
nsmitter?<br>
<br>I mean by typical that the TX has a 4013 type /2 system feeding two FE=
T drivers to drive FETs in a push-pull configuration.<br><br>If I understa=
nd correctly due to the fact MSK does not have amplitude component to its=
 signal that a non-linear transmitter can be used.<br>
<br>So, how do you do this with a Class-D TX as often used in LF/VLF?<br><=
br>Thanks,<br>Scott<br>VE7TIL<br><br><br><br></blockquote></div><br></div>=
</div></blockquote></div><br>

--005045015a6ba5a03004a1600afb--