Return-Path: Received: from mtain-dh04.r1000.mx.aol.com (mtain-dh04.r1000.mx.aol.com [172.29.65.24]) by air-da02.mail.aol.com (v129.10) with ESMTP id MAILINDA024-86624db0a2298a; Thu, 21 Apr 2011 17:31:21 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dh04.r1000.mx.aol.com (Internet Inbound) with ESMTP id 6F4FD380001B4; Thu, 21 Apr 2011 17:31:20 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1QD1Rk-0001j3-CB for rs_out_1@blacksheep.org; Thu, 21 Apr 2011 22:29:56 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1QD1Ri-0001iu-GY for rsgb_lf_group@blacksheep.org; Thu, 21 Apr 2011 22:29:54 +0100 Received: from mail-iw0-f171.google.com ([209.85.214.171]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1QD1Rf-0001eC-KP for rsgb_lf_group@blacksheep.org; Thu, 21 Apr 2011 22:29:54 +0100 Received: by iwn8 with SMTP id 8so165188iwn.16 for ; Thu, 21 Apr 2011 14:29:44 -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=rpmoiYoNI7j7RTWXeg3A9AMSyedVEg9JeeapXfuOFXI=; b=X+f4vAUH6SYCtWNLvK1rf5WSqcST0dXn68XNwV2Oi+8xYmEuyUFJIyn/TSz3jfa6ef /Zr8vF4oet5vOKXdM+5/vHVDApAglsLIuikV1dNYCfH/HOQ5hP5o05jsDzRn1qqvcs2d rQil/mGOR/6PrjPbjc6kXnnDeoytR+1h+/4Co= 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=VJ9qDya7PVhCaS7Hckxb3adXbJeq+Rr7s56kh5KQjgeUw77omr+mE3WDkGqXlOIsRD 4UL39IChwfqAk8lFtRYVeKuXtno8u0OE63xJ0xRGwQTpNbw0D/FYY3Qh1POihGLcbKQ8 vd2w/uRH6WVYYApaSCtABEfgn5Pwr/u/SziPE= MIME-Version: 1.0 Received: by 10.231.117.7 with SMTP id o7mr342275ibq.46.1303421384629; Thu, 21 Apr 2011 14:29:44 -0700 (PDT) Received: by 10.231.207.75 with HTTP; Thu, 21 Apr 2011 14:29:44 -0700 (PDT) In-Reply-To: References: <4DAF42C1.8010401@telus.net> <4DAF7A16.4040208@telus.net> <4DB07212.9020909@freenet.de> Date: Thu, 21 Apr 2011 22:29:44 +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=005045015a6b9f9cd104a1747044 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.6 required=5.0 tests=HTML_20_30, 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-m005.2 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d41184db0a2270d4d X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --005045015a6b9f9cd104a1747044 Content-Type: text/plain; charset=ISO-8859-1 If you can generate the message by replaying from a .WAV file, this ought to be straightforward. Change the sampling rate value in the .WAV file header and it will replay at that rate. But... of course ... you need to be able to generate the file in the first place. The real solution is to do away with the rather pointless divide by two on the input circuitry of these PAs. It is not at all necessary and just makes things complicated. If you can ensure the drive waveform is close to a 50% duty cycle, it can be used directly to drive push-pull FETs after squaring up and generating 180 degress out of phase versions - ie a single inverter.. One way to get a good square waveform out is first to pass your input waveform through a low pass filter, cutting off sharply just above the highest baseband frequency. The reason for the LPF is to eliminate even order (second mainly) harmonics that would skew the subsequent squaring. Even order harmonics aren't important as they will be symmetrical Then pass the waveform into a mid-point biassed comparator with symmetrical hysteresis. Line receivers such as the 26xx32 or 33 will do the job admirably, and work at frequencies up to several MHz. Finally generate antiphase drive signals via logic inverters./ buffers So - LPF + line receiver. + Q / NotQ drive . Simples ! Andy www.g4jnt.com On 21 April 2011 21:58, Rik Strobbe wrote: > Hello Andy, Scott, Wolf, > > indeed WSPR is MFSK, I should be reading mails more carefull. > Some time ago I was thinking about running WSPR with a "divide by 2" class > D PA and wrote a small piece of software that created WSPR audio at double > or quadruple frequency shift. Modulating a SSB TX at 2MHz with quadruple > shift WSPR audio signal produced a nice WSPR signal at 500kHz after divide > by 4. > Due to lack of time I haven't done any on air tests, but if anyone wants to > try I can provide the software. > > Another thought : > If one could "fool" the software about the soundcard sample rate it would > be possible to get frequency doubled audio from any existing sofware. > Ie: Let the software believe that the soundcard is running at 11025Hz > while it is running at 22100Hz. > > 73, Rik ON7YD - OR7T > > ------------------------------ > *Van:* owner-rsgb_lf_group@blacksheep.org [ > owner-rsgb_lf_group@blacksheep.org] namens wolf_dl4yhf [dl4yhf@freenet.de] > *Verzonden:* donderdag 21 april 2011 20:06 > *Aan:* rsgb_lf_group@blacksheep.org > *Onderwerp:* Re: LF: MSK with a Class D transmitter...? > > Hi Rik, > > AFAIK WSPR is not MSK. It's 4-FSK. One of the very exotic modes in WSJT > (not WSPR) was indeed MSK but I don't remember which one. > > About the FET push-pull drive: I wouldn't rely on a windoze PC to produce a > non-overlapping drive signal for the two FETs. Just imagine what happens to > the FETs if windoze decides to play "ding-dong" (through both output > channels) during transmit ;-) > > Cheers, > Wolf . > > Am 21.04.2011 19:46, schrieb Rik Strobbe: > > Hello Scott, > > > > what kind of MSK do you want to transmit ? > > WSPR by any chance ? > > > > 73, Rik ON7YD - OR7T > > > 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 >>>> >>>> >>>> >>>> >>> >> >> > > --005045015a6b9f9cd104a1747044 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
If you can generate the message by replaying from a .WAV file, this= ought to be straightforward.=A0=A0 Change the sampling rate value in the= .WAV file header and it will replay at that rate.=A0=A0 But... of course= ... =A0you need to be able to generate the file in the first place.
=A0
The real solution is to do away with the rather pointless divide by= two on the input circuitry of these PAs.=A0=A0
It is not at all necessary and just makes things complicated.
=A0
If you can ensure the drive waveform is close to a 50% duty cycle, it= can be used directly to drive=A0push-pull FETs after squaring up and gene= rating 180 degress out of phase versions -=A0ie =A0a single inverter..=A0= =A0
=A0
One way to get a good square waveform out is first to pass your input= waveform through a low pass filter, cutting =A0off sharply just above the= highest baseband frequency.=A0=A0=A0 The reason for the LPF is to elimina= te even order (second mainly) harmonics that would skew the subsequent squ= aring.=A0=A0 Even order harmonics aren't important as they will be sym= metrical
=A0
Then pass the waveform into a mid-point biassed comparator with symme= trical hysteresis.=A0=A0 Line receivers such as the 26xx32 or 33 will do= the job admirably, and work at frequencies up to several MHz.=A0 Finally= generate antiphase drive signals via logic inverters./ buffers
=A0
So - LPF=A0+=A0=A0 line receiver.=A0+=A0=A0Q / NotQ drive .=A0=A0=A0= Simples !
=A0
Andy
=A0
=A0


=A0
On 21 April 2011 21:58, Rik Strobbe <Rik.Strobbe@fy= s.kuleuven.be> wrote:
Hello Andy, Scott, Wolf,
=A0
indeed WSPR is MFSK, I should be rea= ding mails more carefull.
Some time ago I was thinking about= running WSPR with a "divide by 2" class D PA and wrote a small= piece of software that created=A0WSPR audio at double or quadruple freque= ncy shift. Modulating a SSB TX at 2MHz with quadruple shift WSPR audio sig= nal produced a nice WSPR signal at 500kHz after divide by 4.
Due to lack of time I haven't do= ne any on air tests, but if anyone wants to try I can provide the software= .
=A0
Another thought :
If one could "fool" the so= ftware about the soundcard sample rate it would be possible to get<= font size=3D"2" face=3D"tahoma">=A0frequency doubled audio from any existi= ng sofware.
Ie: Let= the software believe that the soundcard is running at 11025Hz while it is= running at 22100Hz.
=A0
73, Rik=A0 ON7YD - OR7T<= /font>
=A0
Van: owner-rsgb_lf= _group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens wo= lf_dl4yhf [dl4yhf@f= reenet.de]
Verzonden: donderdag 21 april 2011 20:06
Aan: rsgb_lf_group@black= sheep.org
Onderwerp: Re: LF: MSK with a Class D transmitter.= ..?

Hi Rik,

AFAIK WSPR is not MSK. It's 4-FSK. One of the very= exotic modes in WSJT (not WSPR) was indeed MSK but I don't remember= which one.

About the FET push-pull drive: I wouldn't rely on= a windoze PC to produce a non-overlapping drive signal for the two FETs.= Just imagine what happens to the FETs if windoze decides to play "di= ng-dong" (through both output channels) during transmit ;-)

Cheers,
=A0=A0 Wolf .

Am 21.04.2011 19:46, schrieb Rik Strob= be:=20
Hello Scott,

=A0

what kind of MSK do you want to transm= it ?

WSPR by any chance ?

=A0

73, Rik=A0 ON7YD - OR7T


=A0
On 21 April 2011 01:28, Scott Tilley <sthed= 475@telus.net> 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 usin= g 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 Talbot 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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