Return-Path: Received: from mtain-md01.r1000.mx.aol.com (mtain-md01.r1000.mx.aol.com [172.29.96.85]) by air-me08.mail.aol.com (v129.10) with ESMTP id MAILINME083-8bbe4daf4de23b; Wed, 20 Apr 2011 17:19:30 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-md01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 4CC21380000BA; Wed, 20 Apr 2011 17:19:28 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1QCenO-0006sC-57 for rs_out_1@blacksheep.org; Wed, 20 Apr 2011 22:18:46 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1QCenN-0006s2-KZ for rsgb_lf_group@blacksheep.org; Wed, 20 Apr 2011 22:18:45 +0100 Received: from smtp6.freeserve.com ([193.252.22.192]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1QCenK-0002BA-0U for rsgb_lf_group@blacksheep.org; Wed, 20 Apr 2011 22:18:45 +0100 Received: from me-wanadoo.net (localhost [127.0.0.1]) by mwinf3621.me.freeserve.com (SMTP Server) with ESMTP id A73C3700009B for ; Wed, 20 Apr 2011 23:18:36 +0200 (CEST) Received: from me-wanadoo.net (localhost [127.0.0.1]) by mwinf3621.me.freeserve.com (SMTP Server) with ESMTP id 9AF5370000A0 for ; Wed, 20 Apr 2011 23:18:36 +0200 (CEST) Received: from AGB (customer14511.pool1.Liverpool-MER6166-BAS0001.orangehomedsl.co.uk [91.109.56.182]) by mwinf3621.me.freeserve.com (SMTP Server) with SMTP id 5BF33700009B for ; Wed, 20 Apr 2011 23:18:36 +0200 (CEST) X-ME-UUID: 20110420211836376.5BF33700009B@mwinf3621.me.freeserve.com Message-ID: <3F558BACA835487AA4B9600B9AF13DD9@AGB> From: "Graham" To: References: <4DAF42C1.8010401@telus.net> In-Reply-To: Date: Wed, 20 Apr 2011 22:18:36 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 14.0.8117.416 X-MimeOLE: Produced By Microsoft MimeOLE V14.0.8117.416 X-Antivirus: avast! (VPS 110420-1, 20/04/2011), Outbound message X-Antivirus-Status: Clean X-Spam-Score: 0.3 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,MAILTO_TO_SPAM_ADDR=0.276 Subject: Re: LF: MSK with a Class D transmitter...? Content-Type: multipart/alternative; boundary="----=_NextPart_000_01DE_01CBFFA8.E464C8F0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=2.0 required=5.0 tests=HTML_30_40,HTML_MESSAGE, MAILTO_TO_SPAM_ADDR,MISSING_OUTLOOK_NAME autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false x-aol-global-disposition: G x-aol-sid: 3039ac1d60554daf4de06bd3 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none ------=_NextPart_000_01DE_01CBFFA8.E464C8F0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Its the shift that's the problem , going for a x2 audio may = drop you out side the ssb filter pass band .....=20 From: Andy Talbot=20 Sent: Wednesday, April 20, 2011 10:09 PM To: rsgb_lf_group@blacksheep.org=20 Subject: Re: LF: MSK with a Class D transmitter...? 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. Sa= me ideas for frequency doubling can be used. See http://www.g4jnt.com/LFUpconv.pdf for a direct from audio upconve= rter. Must fully check before hitting SEND ! Andy G4JNT On 20 April 2011 21:50, Andy Talbot 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, pas= s 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. Del= ay 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 / buffe= r pair to generate the out of phase drive signals. The input now ne= eds to be close to a 1:1 squarwave at output frequency. Pass the sou= ndcard audio into a comparator and make sure it gives a 50% duty cycle= s. Andy www.g4jnt.com ps.=20 or 3) Convince the software author the S/W needs modifying to giv= e a 2.F output On 20 April 2011 21:32, Scott Tilley wrote: Hi All I wonder if someone can explain to me how to feed an MSK signal in= to a typical Class D transmitter? I mean by typical that the TX has a 4013 type /2 system feeding tw= o FET drivers to drive FETs in a push-pull configuration. If I understand correctly due to the fact MSK does not have amplit= ude 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 ------=_NextPart_000_01DE_01CBFFA8.E464C8F0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Its the  shift that's  the&= nbsp;=20 problem  , going  for a  x2  audio  may = =20 drop  you  out  side the  ssb  filter = pass =20 band .....

Sent: Wednesday, April 20, 2011 10:09 PM
Subject: Re: LF: MSK with a Class D=20 transmitter...?

Bin too quick to type..
NOt thinking straight...
 
You need to the upconvert either the resulting doubled audio tone= by twice=20 the RF carrier, or upconvert first and double the final RF.  Same= ideas for=20 frequency doubling can be used.
 
See http://www.g4= jnt.com/LFUpconv.pdf =20 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>=20 wrote:
I assume you are genrating the MSK from soundcard output,= in which=20 case two options come to mind:
 
1)  Double the frequency.  Full wave rectify the audi= o=20 sinusoid, pass the AC part of the result into a comparator and into&= nbsp;the=20 divider.  Alternatively, as the signal bandwidth is probab= ly quite=20 low, square up the audio to start with, feed into one inpiut of an= XOR=20 gate.  Delay the waveform by 90 deg and feed this into the othe= side of=20 the XOR.    Output of XOR to divider as before
 
2)   Remove the  divide by two, and replace with= an=20 inverter / buffer pair to generate the out of phase drive signals.&n= bsp; =20 The  input now needs to be close to a 1:1 squarwave at out= put=20 frequency.   Pass the soundcard audio into a comparator an= d make=20 sure it gives a 50% duty cycles.
 
 
Andy
 
ps.=20
or 3)    Convince the software author the S/W ne= eds=20 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=20 feed an MSK signal into a typical Class D transmitter?

I me= an by=20 typical that the TX has a 4013 type /2 system feeding two FET driv= ers to=20 drive FETs in a push-pull configuration.

If I understand co= rrectly=20 due to the fact MSK does not have amplitude component to its signa= l that a=20 non-linear transmitter can be used.

So, how do you do this= with a=20 Class-D TX as often used in=20 LF/VLF?

Thanks,
Scott
VE7TIL







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