Return-Path: Received: from mtain-di02.r1000.mx.aol.com (mtain-di02.r1000.mx.aol.com [172.29.64.6]) by air-mc03.mail.aol.com (v129.4) with ESMTP id MAILINMC031-a8db4d77a321c5; Wed, 09 Mar 2011 10:56:17 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-di02.r1000.mx.aol.com (Internet Inbound) with ESMTP id 68DF4380000BB; Wed, 9 Mar 2011 10:56:09 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1PxLjR-0008NB-W0 for rs_out_1@blacksheep.org; Wed, 09 Mar 2011 15:55:25 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1PxLjR-0008Mz-Fa for rsgb_lf_group@blacksheep.org; Wed, 09 Mar 2011 15:55:25 +0000 Received: from out1.ip08ir2.opaltelecom.net ([62.24.128.244]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1PxLjP-0004nL-7Y for rsgb_lf_group@blacksheep.org; Wed, 09 Mar 2011 15:55:25 +0000 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AgkBAN4xd01cHYpN/2dsb2JhbACDO5ERA4Nzjix0w1mDAYJkBIFwjiyDAg X-IronPort-AV: E=Sophos;i="4.62,291,1297036800"; d="scan'208,217";a="482712593" Received: from unknown (HELO xphd97xgq27nyf) ([92.29.138.77]) by out1.ip08ir2.opaltelecom.net with SMTP; 09 Mar 2011 15:55:15 +0000 Message-ID: <003201cbde72$606d6090$0401a8c0@xphd97xgq27nyf> From: "mal hamilton" To: References: Date: Wed, 9 Mar 2011 15:55:12 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: LF: Re: VLF Stability and soundcard locking Content-Type: multipart/alternative; boundary="----=_NextPart_000_002F_01CBDE72.60107380" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_20_30,HTML_MESSAGE 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: 3039ac1d40064d77a319393d X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none ------=_NextPart_000_002F_01CBDE72.60107380 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable I agree with these comments, and have said it before. If all radio amateurs on all the other bands used this system of uh ba= ndwidths and day long qso's Amateur Radio would cease as a hobby. The aim should be to generate enough ERP so that a qso could take plac= e in a reasonably short time and be observed by others in say QRS 3 -= 60. SWL listeners/viewers could also particpate. The Dreamers band will fizzle out if transmitted signals are not impro= ved so that a larger audience can engage in the activities.=20 also who is going to buy a PCM2900 or similar gadgets for a ONE OFF QS= O if you are lucky. Again QSL reports on frequency alone are not VALID - it could be any= carrier. G3KEV =20 ----- Original Message -----=20 From: Andy Talbot=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Tuesday, March 08, 2011 8:42 PM Subject: LF: VLF Stability and soundcard locking It would appear that a typical soundcard isn't stable enough for VLF= use when stations are running 1mHz bandwidth signalling, and using an= y locking option to other off-air signals is a bit restrictive in what= software you can run. It may be worth looking at a custom codec driven from a locked frequ= ency source. The PCM2900 (which costs only a few pounds from Farnell= , and they supply the data sheet) is a self contained USB codec which= needs only a handful of additional components for a USB soundcard wit= h stereo line input and output. For normal operation it needs a 12= MHz crystal, but an external 12MHz source can be used which could be= locked to, or derived from, a high stability reference. Even a TCXO= on its own with typically 1ppm accuracy / stability would be better= than any normal 20ppm crystal I've built one of these codecs, but have yet to confirm the resultin= g sampling rate(s) are exactly what they should be. By the time it ha= s gone through USB packetising and Windows' drivers I hope full synch= ronicity is maintained right through to the user software. This may= only be the case for sampling rates like 12000Hz - it all depends wha= t windows does. Exact conversion is needed for this solution to be= worthwhile, not just a close approximation. Andy www.g4jnt.com ------=_NextPart_000_002F_01CBDE72.60107380 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
I agree with these comments, and have said it= =20 before.
If all radio amateurs on all the other bands= used this=20 system of uh bandwidths and day long qso's Amateur Radio would cease= as a=20 hobby.
The aim should be to generate enough ERP so th= at a=20 qso could take place in a reasonably short time and be observed by oth= ers in say=20 QRS 3 - 60. SWL listeners/viewers could also particpate.
The Dreamers band will fizzle out if tran= smitted=20 signals are not improved so that a larger audience can engage in the= =20 activities. 
also who is going to buy a PCM2900 or similar&= nbsp;gadgets=20 for a ONE OFF QSO if you are lucky.
Again QSL reports on frequency alone are not= VALID - it=20 could be any carrier.
G3KEV
 
 
----- Original Message -----
From:=20 Andy=20 Talbot
Sent: Tuesday, March 08, 2011= 8:42=20 PM
Subject: LF: VLF Stability an= d soundcard=20 locking

It would appear that a typical soundcard isn't stable enou= gh for VLF=20 use when stations are running 1mHz bandwidth signalling, and using= any locking=20 option to other off-air signals is a bit restrictive in what softwar= e you can=20 run.
 
It may be worth looking at a custom codec driven from a locked= frequency=20 source.   The PCM2900 (which costs only a few pounds = from=20 Farnell, and they supply the data sheet) is a self contained USB cod= ec which=20 needs only a handful of additional components for a USB soundcard wi= th stereo=20 line input and output.     For normal operation= it needs a=20 12MHz crystal, but an external 12MHz source can be used which= could be=20 locked to, or derived from, a high stability reference.  Even= a TCXO on=20 its own with typically 1ppm accuracy / stability would be bette= r than any=20 normal 20ppm crystal
 
I've built one of these codecs, but have yet to confirm th= e=20 resulting sampling rate(s) are exactly what=20 they should be.  By the time it has gone through USB packe= tising and=20 Windows'  drivers I hope full synchronicity is maintained right= through=20 to the user software.   This may only be the case for samp= ling rates=20 like 12000Hz - it all depends what windows does.   Exact= conversion=20 is needed for this solution to be worthwhile, not just a close=20 approximation.
 
Andy
 
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