Return-Path: Received: from mtain-mp06.r1000.mx.aol.com (mtain-mp06.r1000.mx.aol.com [172.29.193.74]) by air-ma04.mail.aol.com (v129.10) with ESMTP id MAILINMA043-b5194db068551ae; Thu, 21 Apr 2011 13:24:37 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mp06.r1000.mx.aol.com (Internet Inbound) with ESMTP id 975A8380000BB; Thu, 21 Apr 2011 13:24:35 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1QCxat-0000cS-RW for rs_out_1@blacksheep.org; Thu, 21 Apr 2011 18:23:07 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1QCxat-0000cJ-2N for rsgb_lf_group@blacksheep.org; Thu, 21 Apr 2011 18:23:07 +0100 Received: from mail-iw0-f171.google.com ([209.85.214.171]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1QCxaq-0005sq-K1 for rsgb_lf_group@blacksheep.org; Thu, 21 Apr 2011 18:23:07 +0100 Received: by iwn8 with SMTP id 8so2420308iwn.16 for ; Thu, 21 Apr 2011 10:22:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:in-reply-to:references:date :message-id:subject:from:to:content-type; bh=o0cV64z5YELMt0n8JYiPccCEu3PZbMQPBvP3Cw3tWEk=; b=Jgtvbut8XyDb/WvM83pUaPZOa+AU8/jZzN02h9v9+8fGKA78yuVEbr0Uuijg4C1jKq KWqzb2dEeJ1G63au6suyOCRaj8KS3tBkBinegS4jI4MW9TohSsSUqQykKTxXGOulphRt ADf7g3GEIRE8onG9kzpgqyYyZkksSTz+sUrqM= 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=GYesnlLbG7d3jdRQq5ij7h4rqfV84/dAKHiq9w7tXDVP1NnKosG7MDMD68P2+kLNPx b+dlxEY+MXCy/Vo9QIn9KQSVSrAknXNlXp38+a/CaO+sQXOY4v27uNdi+063fDRxJQUK fIqlhwJHMJSXbhSSYWwa1MJxpJyeVPSP8MDiY= MIME-Version: 1.0 Received: by 10.231.117.7 with SMTP id o7mr175021ibq.46.1303406577707; Thu, 21 Apr 2011 10:22:57 -0700 (PDT) Received: by 10.231.207.75 with HTTP; Thu, 21 Apr 2011 10:22:57 -0700 (PDT) In-Reply-To: <4DAF7A16.4040208@telus.net> References: <4DAF42C1.8010401@telus.net> <4DAF7A16.4040208@telus.net> Date: Thu, 21 Apr 2011 18:22:57 +0100 Message-ID: From: Andy Talbot To: rsgb_lf_group@blacksheep.org DomainKey-Status: good (testing) 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=005045015a6b12361a04a170fead X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.2 required=5.0 tests=HTML_FONTCOLOR_UNSAFE, HTML_MESSAGE,MAILTO_TO_SPAM_ADDR 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-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-m219.1 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1dc14a4db068523afb X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --005045015a6b12361a04a170fead Content-Type: text/plain; charset=ISO-8859-1 I was half asleep last night when I first replied - hence the confusion over upconversion. As you're on 9kHz, converting doesn't apply and the PC generates direct Tx drive. The quadrature bit is not needed for direct output, so you only use one audio channel. As mentioned by several writers now, you need to double the frequency first to pass into your divide by 2, or bypass that and drive the transmitter directly - after making sure the waveform is very close to a 50% duty cycle square wave. The drive will almost certainly have to be push-pull, so you'll need to make a squarer / comparator and generate Q/Q-bar drive signals Andy (doesn't do late-at-night :-) G4JNT On 21 April 2011 01:28, Scott Tilley wrote: > Hi Andy > > Holy mind bogglingness batman... > > Here's the parameters to make this real simple: > - I want to generate a MSK signal out of the transmitter at 8970Hz. > - I'm using Spectrum Lab, which allows me to create a MSK drive and at a > baud rate I want at any frequency my sound card can generate. > - SL allows me to output quadrature outputs. > > So, If I understand correctly pump said FET driver with the quadrature > outputs from the sound card audio (squaring up the sine waves of course) and > it should work? > > Thanks, > Scott > > > > > > > On 4/20/2011 2:09 PM, Andy Talbot wrote: > > 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 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 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 >>> >>> >>> >>> >> > > --005045015a6b12361a04a170fead Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
I=A0was half asleep last night when I first replied - hence the confu= sion over upconversion.=A0=A0As you're on=A09kHz, converting doesn'= ;t apply and the PC generates direct Tx drive.=A0 The quadrature bit is no= t needed=A0for direct output, so you only use one audio channel.
=A0
As mentioned by several writers =A0now, you need to double the freque= ncy first to pass into your divide by 2, or bypass that and drive the tran= smitter directly - after making sure the waveform is very close to a 50%= duty cycle square wave.=A0=A0 The drive will almost certainly have to be= push-pull, so you'll need to make a squarer / comparator and generate= Q/Q-bar drive signals
=A0
Andy=A0=A0(doesn't do late-at-night :-)=A0 G4JNT=A0=A0=A0


=A0
On 21 April 2011 01:28, Scott Tilley <sthed475@telus.net&= gt; wrote:
Hi Andy

Holy mind bogglin= gness batman...

Here's the parameters to make this real simple:=
- I want to generate a MSK signal out of the transmitter at 8970Hz.- I'm using Spectrum Lab, which allows me to create a MSK drive and= at a baud rate I want at any frequency my sound card can generate.
- SL allows me to output quadrature outputs.

So, If I understand co= rrectly pump said FET driver with the quadrature outputs from the sound ca= rd audio (squaring up the sine waves of course) and it should work?
Thanks,
Scott=20






On 4/20/2011 2:09 PM, Andy Talbo= t wrote:=20
Bin too quick to type..
NOt thinking straight...
=A0
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.
=A0
See h= ttp://www.g4jnt.com/LFUpconv.pdf=A0 for a direct from audio upconverte= r.
=A0
Must fully check before hitting SEND !
=A0
Andy
G4JNT

On 20 April 2011 21:50, Andy Talbot <and= y.g4jnt@gmail.com> wrote:
I assume you are genrating the MSK=A0from soundcard output, in which= case two options come to mind:
=A0
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
=A0
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.
=A0
=A0
Andy
=A0
ps.=20
or 3)=A0=A0=A0 Convince the software author the S/W needs modifying= to give a 2.F output
=A0
=A0
On 20 April 2011 21:32, Scott Tilley <sthed= 475@telus.net> wrote:
Hi All

I= wonder if someone can explain to me how to feed an MSK signal into a typi= cal Class D transmitter?

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.

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.

So, how do you do this with a Class-D TX as often used in LF/VLF?
<= br>Thanks,
Scott
VE7TIL




=



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