Return-Path: X-Spam-DCC: paranoid 1102; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-2.4 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, HTML_MESSAGE autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id tAPNV2IC023949 for ; Thu, 26 Nov 2015 00:31:02 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1a1jTt-0003xe-6T for rs_out_1@blacksheep.org; Wed, 25 Nov 2015 23:28:09 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1a1jTs-0003xO-Hp for rsgb_lf_group@blacksheep.org; Wed, 25 Nov 2015 23:28:08 +0000 Received: from mail-wm0-f50.google.com ([74.125.82.50]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128) (Exim 4.86) (envelope-from ) id 1a1jSv-00064f-9E for rsgb_lf_group@blacksheep.org; Wed, 25 Nov 2015 23:28:07 +0000 Received: by wmec201 with SMTP id c201so7872497wme.0 for ; Wed, 25 Nov 2015 15:26:52 -0800 (PST) X-DKIM-Result: Domain=gmail.com Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=Tk1s7rCObjJYURKLLWagttIqbPmUGlQcsOh1OUi7Zbo=; b=DVQsZw53o5P2qh+UqNNjf7lbK57SVsdIGSvl2umrsjino3Ty2hFvaQR0BooF0Tom2H m6webi8ikfnM5uNjg4mrHI2oYOLv7iGhFf5dEp0v8BSedcSXFjce73u8wzJaJLdkk3g4 XSyR3jtzXR4dgWbJgtcD0VgDVO492QOjm27kUQt+ZAKWu850O3zjmDkBTUb9UIem0E3B o6wF6IKO+v6r/iwnHixsmXbgOaG5eLD3B1Po+TNgD/+qNjuU3Us5Heu2tUhLY9DRkPZ5 yssh3/WTj1g2V9ThnrQx2PffI2cIXdU8xY1mz8B2VEYT0j3lypQyjnwqp971j14irNJP PTKw== MIME-Version: 1.0 X-Received: by 10.28.9.138 with SMTP id 132mr230803wmj.19.1448494012808; Wed, 25 Nov 2015 15:26:52 -0800 (PST) Received: by 10.28.130.139 with HTTP; Wed, 25 Nov 2015 15:26:52 -0800 (PST) In-Reply-To: <56563AA4.7080606@posteo.de> References: <56563AA4.7080606@posteo.de> Date: Wed, 25 Nov 2015 23:26:52 +0000 Message-ID: From: Andy Talbot To: rsgb_lf_group@blacksheep.org X-Scan-Signature: 052e5a7ab87161a07560b72babff3441 Subject: Re: LF: Alternative high resolution frequency source for LF Content-Type: multipart/alternative; boundary=001a11443d9e17c6df052565cbda 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-Scanned-By: MIMEDefang 2.56 on 10.1.3.10 Status: O X-Status: X-Keywords: X-UID: 5331 --001a11443d9e17c6df052565cbda Content-Type: text/plain; charset=UTF-8 Fref 10 MHz R div 20 VCO / Output Divider 50 External Divider 512 Final output freqeuncy 137000.5120 Hz Step Size 10 uHz DDS Chip Output Freq 70.14426 MHz VCO Fundamental 3507.213108 MHz Fcomp 0.5000 MHz Step size at VCO 0.256 Hz Denominator D 1953125 Fract F 832452 N divider 7014 Actual Output Freq 137000.51202 Hz Actual Output step 10.0000 uHz Output Error 0.00 uHz On 25 November 2015 at 22:48, DK7FC wrote: > Hmm, > > Use *Spectrum Lab* with a GPS reference signal, compensating the > soundcard drift, and a GPS-locked mixer and you're down in the 10 uHz range > and also ready for nearly any mode used on the band! :-) > > 73, Stefan > > Am 25.11.2015 23:00, schrieb Andy Talbot: > > Although DDS sources seem to more-or-less dominate where high resolution / > accuracy is needed, there is another route that could be worth > investigating: Fractional-N synthesis with addtional dividers. > > For example, the LMX2541 with a 10MHz reference phase comparator input > will generate steps as low as 2.38Hz at its minimum internal VCO frequency > of 2.2GHz. A programmable output divider goes to divide-by 63, allowing > steps of 0.038Hz at 35MHz . Add a single chip binary divider of 256 (for > the 137kHz band) and you're down to 150uHz steps - which are completely > deterministic. > > Since phase noise and Fract-N sidebands are hardly an issue with this > degree of output division, the phase comparator could be operated at a much > lower frequency, say 500kHz, allowing steps of lower than 10uHz. Which > is a significantly higher resolution than the 2.3mHz steps the traditional > AD9850 32 bit DDS offers. > > I've used these Fract-N devices extensively at microwaves, see > http://www.g4jnt.com/LMX2541_Synth_Module.pdf , but haven't yet turned > one into an LF exciter > > Andy G4JNT > > --001a11443d9e17c6df052565cbda Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Fref 10 MHz
R div 20
VCO / Output Divider 50
External Divider 512
Final output freqeuncy= 137000.5120 Hz
Step Size 10 uHz
DDS Chip Output Freq 70.14426 MHz
VCO Fundamental 3507.213108 MHz
Fcomp 0.5000 MHz
Step size at VCO 0.256 Hz
Denominator D 1953125
Fract=C2=A0 F 832452
N divider 7014
Actual Output Freq 137000.51202 Hz
Actual Output=C2=A0 st= ep 10.0000 uHz
Output Error 0.00 uHz

On 25 November 2015 at 22:48, DK7FC <selberdenken@posteo.de&= gt; wrote:
=20
Hmm,

Use Spectrum Lab with a GPS reference signal, compensating the soundcard drift, and a GPS-locked mixer and you're down in the 10 uHz range and also ready for nearly any mode used on the band! :-)

73, Stefan

Am 25.11.2015 23:00, schrieb Andy Talbot:
Although DDS sources seem to more-or-less dominate where high resolution / accuracy is needed, there is another route that could be worth investigating: =C2=A0 Fractional-N synthesis with addtional dividers.

For example, the LMX2541 =C2=A0with a =C2=A010MHz reference =C2=A0ph= ase comparator input will generate steps as low as 2.38Hz at its minimum internal VCO frequency of 2.2GHz.=C2=A0 A programmable output divider goes to divide-by 63, allowing steps of 0.038Hz at 35MHz .=C2=A0 Add a single chip binary divider of 256 (for the 137kHz band) =C2=A0and you're down = to 150uHz steps - which are completely deterministic.

Since phase noise and Fract-N sidebands are hardly an issue with this degree of output division, the phase comparator could be operated at a much lower frequency, say 500kHz, allowing steps of =C2=A0lower than 10uHz. =C2=A0 Which is a significantly higher resolution than the 2.3mHz steps the traditional AD9850 32 bit DDS offers.=C2=A0

I've used these Fract-N devices extensively at microwaves, =C2= =A0see http://www.g4jnt.com/LMX2541_Synth_Module.pdf , =C2=A0 =C2=A0but haven't yet turned one into an LF exciter

Andy =C2=A0G4JNT

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