Return-Path: Received: from mtain-mk03.r1000.mx.aol.com (mtain-mk03.r1000.mx.aol.com [172.29.97.135]) by air-me06.mail.aol.com (v129.10) with ESMTP id MAILINME064-8bb74db07174bf; Thu, 21 Apr 2011 14:03:32 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mk03.r1000.mx.aol.com (Internet Inbound) with ESMTP id C66B93800019D; Thu, 21 Apr 2011 14:03:29 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1QCyCy-0000xI-Fy for rs_out_1@blacksheep.org; Thu, 21 Apr 2011 19:02:28 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1QCyCx-0000x9-Hg for rsgb_lf_group@blacksheep.org; Thu, 21 Apr 2011 19:02:27 +0100 Received: from defout.telus.net ([204.209.205.30]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1QCyCw-0006eF-6I for rsgb_lf_group@blacksheep.org; Thu, 21 Apr 2011 19:02:27 +0100 Received: from edmwcm03 ([204.209.205.13]) by priv-edmwes50.telusplanet.net (InterMail vM.8.01.03.00 201-2260-125-20100507) with ESMTP id <20110421180223.DHXI8015.priv-edmwes50.telusplanet.net@edmwcm03> for ; Thu, 21 Apr 2011 12:02:23 -0600 Received: from [192.168.1.74] ([75.157.142.115]) by edmwcm03 with bizsmtp id aJ2N1g01Y2Vbb3f01J2Niz; Thu, 21 Apr 2011 12:02:23 -0600 X-Telus-Outbound-IP: 75.157.142.115 X-Authority-Analysis: v=1.1 cv=WnW4EIPqW+UOuPrckVMDJ6NmVUA+0GaxzzKoDf/5uIg= c=1 sm=2 a=jVez_htjv6wA:10 a=VcZ9ZI0UkD4A:10 a=LGgl8L9ij00A:10 a=aatUQebYAAAA:8 a=wV9FcBFsAAAA:8 a=pGLkceISAAAA:8 a=3MpPSjpHV7q37q04_poA:9 a=-HDsYqN6ocxmyTrop_QA:7 a=wPNLvfGTeEIA:10 a=rBKJJ2Jc0C4A:10 a=MSl-tDqOz04A:10 a=SeTUjpOZTIy9UyZX1mkA:9 a=4ldw00RpMQihcu4aoYMA:7 Message-ID: <4DB0712E.1050304@telus.net> Date: Thu, 21 Apr 2011 11:02:22 -0700 From: Scott Tilley User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.15) Gecko/20110303 Lightning/1.0b2 Thunderbird/3.1.9 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <4DAF42C1.8010401@telus.net> <4DAF7A16.4040208@telus.net> In-Reply-To: X-Spam-Score: 1.7 (+) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,MAILTO_TO_SPAM_ADDR=0.276,RATWARE_GECKO_BUILD=1.426 Subject: Re: LF: MSK with a Class D transmitter...? Content-Type: multipart/alternative; boundary="------------000809060701000903090401" 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=FROM_ENDS_IN_NUMS, 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-sid: 3039ac1d61874db0717130a8 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --------------000809060701000903090401 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Thanks Andy! Sanity check now complete. I did as you described before I asked the general question and strange things happened... I'm going to need to double check what I was doing to ensure I didn't succumb to the late at night syndrome. As the basic premise you and other share made complete sense to me until I tried it and it didn't seem to work... Will report when I get some results... On another note, I was able to detect the 8.970KHz test carrier from my Earth conduction tests at the 9km mark yesterday. Interestingly there seemed to be QSB on the signal at that range. More testing today. Caps on order for the 'Air loop'. 73 Scott VE7TIL On 4/21/2011 10:22 AM, Andy Talbot wrote: > 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 >> >> >> >> >> > > --------------000809060701000903090401 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Thanks Andy!

Sanity check now complete.  I did as you described before I asked the general question and strange things happened... 

I'm going to need to double check what I was doing to ensure I didn't succumb to the late at night syndrome. As the basic premise you and other share made complete sense to me until I tried it and it didn't seem to work...

Will report when I get some results...

On another note, I was able to detect the 8.970KHz test carrier from my Earth conduction tests at the 9km mark yesterday.  Interestingly there seemed to be QSB on the signal at that range.  More testing today.

Caps on order for the 'Air loop'. 

73 Scott
VE7TIL

  

On 4/21/2011 10:22 AM, Andy Talbot wrote:
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 <sthed475@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 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 <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
 
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








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