Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-ma02.r1000.mx.aol.com (Internet Inbound) with ESMTP id B4B0338000095; Mon, 20 Feb 2012 15:09:39 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1RzZXA-0007fp-Fc for rs_out_1@blacksheep.org; Mon, 20 Feb 2012 20:08:28 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1RzZX8-0007fg-L4 for rsgb_lf_group@blacksheep.org; Mon, 20 Feb 2012 20:08:26 +0000 Received: from smtpout3.wanadoo.co.uk ([80.12.242.59] helo=smtpout.wanadoo.co.uk) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1RzZX5-0005UP-WB for rsgb_lf_group@blacksheep.org; Mon, 20 Feb 2012 20:08:26 +0000 Received: from AGB ([2.26.22.98]) by mwinf5d41 with ME id cL8H1i00D26ybSy03L8Hpn; Mon, 20 Feb 2012 21:08:18 +0100 Message-ID: From: "Graham" To: References: In-Reply-To: Date: Mon, 20 Feb 2012 20:08:17 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 14.0.8117.416 X-MimeOLE: Produced By Microsoft MimeOLE V14.0.8117.416 X-Antivirus: avast! (VPS 120220-1, 20/02/2012), Outbound message X-Antivirus-Status: Clean X-Spam-Score: 0.2 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,RCVD_ILLEGAL_IP=0.234 Subject: Re: LF: Measurements on 10MHz references Content-Type: multipart/alternative; boundary="----=_NextPart_000_0121_01CCF00B.624B99D0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.6 required=5.0 tests=HTML_20_30,HTML_MESSAGE, MISSING_OUTLOOK_NAME 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-SCORE: 0:2:367837504:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d600a4f42a8834e76 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. ------=_NextPart_000_0121_01CCF00B.624B99D0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable >>generate 5MHz which was doubled for these measurements using a = full-wave rectifier doubler.<< Can you do that ? From: Andy Talbot=20 Sent: Monday, February 20, 2012 7:00 PM To: ukmicrowaves@yahoogroups.com ; rsgb_lf_group@blacksheep.org ; = uk_beacons@yahoogroups.com=20 Subject: LF: Measurements on 10MHz references In the file http://www.g4jnt.com/DownLoad/10MHz_ReferenceSpurii.pdf = are plots of the 10MHz outputs from several 10MHz references and = oscillators. =20 They include four GPSDOs of varying types, an HP5061 Caesium standard, = an oldish high quality TCXO recovered from a 1980's vintage STL comms = receiver, and my long in the tooth MSF frequency reference using a = Toyocom OCXO. =20 This latter, and the Cs standard, both generate 5MHz which was doubled = for these measurements using a full-wave rectifier doubler. All plots were made using an SDR-IQ on the same settings: 0.37Hz FFT bin = at spans of 10kHz and 100kHz with 4 times averaging. The final two = measurements on the two Simple GPSDOs were made by G0API using his = SDR-IQ with the same setup as mine. For all plots, signal level / = attenuation were adjusted to be as close to full scale as possible = without overload. Some artefacts at the -100dBc to -110dBc region seem to be in common = across several plots, and I suspect these are locally generated or due = to the SDR-IQ. However, there are enough and sufficient differences to = see that some sources are definltely better than others, and that the = cheaper cost conditioners do allow spurious signals onto the output. My own ZAZ GPSDO, the second set of plots, originally showed unstable = sidebands at 650Hz which I realised were coming from an LCD backlight = inverter. With this removed, it is now shown to be one of the better = sources - but with the high spec TCXO that was recovered from the old = Decca Navigator chain, berhaps not too surprising. =20 Teh second ZAZ plot, using the modern Morion OCXO is the cleanest in = terms of spuriou, although the phase noise of that oscillator is higher = than many of the others. This is, I believe, characteristic of that = OCXO which was used originally mainly as a a timing unit, specifically = for its fast warm up and low retrace errors rather than for its noise = performance. Andy www.g4jnt.com ------=_NextPart_000_0121_01CCF00B.624B99D0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
>>generate 5MHz which was doubled for these measurements = using a=20 full-wave rectifier doubler.<<
 
Can you  do  that  ?

From: Andy Talbot
Sent: Monday, February 20, 2012 7:00 PM
To: ukmicrowaves@yahoogroups.com= ; rsgb_lf_group@blacksheep.org= ; uk_beacons@yahoogroups.com=
Subject: LF: Measurements on 10MHz = references

In the file    http://w= ww.g4jnt.com/DownLoad/10MHz_ReferenceSpurii.pdf   =20 are plots of the 10MHz outputs from several 10MHz references and=20 oscillators.  
They include four GPSDOs of varying types, an HP5061 Caesium = standard,=20 an oldish high quality TCXO recovered from a 1980's vintage STL comms = receiver,=20 and my long in the tooth MSF frequency reference using a Toyocom = OCXO. =20
This latter, and the Cs standard, both generate 5MHz which was = doubled=20 for these measurements using a full-wave rectifier doubler.
 
All plots were made using an SDR-IQ on the same settings: 0.37Hz = FFT bin at=20 spans of 10kHz and 100kHz with 4 times averaging.  The final two=20 measurements on the two Simple GPSDOs were made by G0API using his = SDR-IQ with=20 the same setup as mine.   For all plots, signal level / = attenuation=20 were adjusted to be as close to full scale as possible without = overload.
 
Some artefacts at the -100dBc to -110dBc region seem to be in = common across=20 several plots, and I suspect these are locally generated or due to the=20 SDR-IQ.   However, there are enough and sufficient differences = to see=20 that some sources are definltely better than others, and that the = cheaper cost=20 conditioners do allow spurious signals onto the output.
 
My own ZAZ GPSDO, the second set of plots, originally showed = unstable=20 sidebands at 650Hz which I realised were coming from an LCD = backlight=20 inverter.  With this removed, it is now shown to be one of the = better=20 sources - but with the high spec TCXO that was recovered from the old = Decca=20 Navigator chain, berhaps not too surprising.  
 
Teh second ZAZ plot, using the modern Morion OCXO is the cleanest = in terms=20 of spuriou, although the phase noise of that oscillator is higher than = many of=20 the others.   This is, I believe, characteristic of that OCXO = which=20 was used originally mainly as a a timing unit, specifically  for = its fast=20 warm up and low retrace errors rather than for its noise = performance.
 
 
Andy
 
------=_NextPart_000_0121_01CCF00B.624B99D0--