Return-Path: X-Spam-DCC: paranoid 1170; Body=3 Fuz1=3 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: ** X-Spam-Status: No, score=2.2 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, FORGED_MUA_OUTLOOK,HTML_40_50,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 tA1M3H6w015054 for ; Sun, 1 Nov 2015 23:03:17 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Zt0ey-0005TW-02 for rs_out_1@blacksheep.org; Sun, 01 Nov 2015 21:59:32 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Zt0ex-0005TN-HT for rsgb_lf_group@blacksheep.org; Sun, 01 Nov 2015 21:59:31 +0000 Received: from rgout0203.bt.lon5.cpcloud.co.uk ([65.20.0.202]) by relay1.thorcom.net with esmtp (Exim 4.86) (envelope-from ) id 1Zt0dt-0007K1-CL for rsgb_lf_group@blacksheep.org; Sun, 01 Nov 2015 21:59:30 +0000 X-OWM-Source-IP: 86.178.169.152 (GB) X-OWM-Env-Sender: alan.melia@btinternet.com X-CTCH-RefID: str=0001.0A090205.56368AF1.000D,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0 X-Junkmail-Premium-Raw: score=39/50,refid=2.7.2:2015.10.24.122715:17:39.532,ip=86.178.169.152,rules=__HAS_MSGID, __SANE_MSGID, MSGID_32HEX_LC, INVALID_MSGID_NO_FQDN, __MSGID_32HEX, __HAS_FROM, __PHISH_FROM2, __FRAUD_WEBMAIL_FROM, __TO_MALFORMED_2, __TO_NO_NAME, __REFERENCES, __BOUNCE_CHALLENGE_SUBJ, __BOUNCE_NDR_SUBJ_EXEMPT, __MIME_VERSION, __CT, __CTYPE_MULTIPART_ALT, __CTYPE_HAS_BOUNDARY, __CTYPE_MULTIPART, __HAS_X_PRIORITY, __HAS_MSMAIL_PRI, __HAS_X_MAILER, USER_AGENT_OE, __OUTLOOK_MUA_1, __USER_AGENT_MS_GENERIC, __ANY_URI, __FRAUD_BODY_WEBMAIL, __URI_NO_WWW, __URI_NO_PATH, __CP_MEDIA_BODY, __C230066_P2, __INT_PROD_GPS, __SUBJ_ALPHA_NEGATE, SUPERLONG_LINE, __HTML_AHREF_TAG, __HAS_HTML, HTML_NO_HTTP, BODY_SIZE_10000_PLUS, __MIME_HTML, __TAG_EXISTS_HTML, RDNS_GENERIC_POOLED, __URI_NS, SXL_IP_DYNAMIC[152.169.178.86.fur], RDNS_SUSP_GENERIC, __PHISH_FROM, __OUTLOOK_MUA, RDNS_SUSP, __FRAUD_WEBMAIL, FORGED_MUA_OUTLOOK, REFERENCES, NO_URI_HTTPS X-CTCH-Spam: Unknown Received: from gnat (86.178.169.152) by rgout02.bt.lon5.cpcloud.co.uk (8.6.122.06) (authenticated as alan.melia@btinternet.com) id 561CC1010231D345 for rsgb_lf_group@blacksheep.org; Sun, 1 Nov 2015 21:58:04 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=btinternet.com; s=btcpcloud; t=1446415100; bh=CXxoeR/bQRRR5NmPe/2z3M4RbIWscIo1tp+xz0/z0R8=; h=Message-ID:From:To:References:Subject:Date:MIME-Version:X-Mailer; b=wFO+BkgG2hrhs+SJebok+uoJHqbxiCV/BuAmjmJGf8yu5U0i5zBGPSjqi90yX8KYkLKfr7GnHIhXvRaLfHEV4CUC7WaWEzv5W69E9FnpLEReTv4X6cZtRP98pt7Tc/jcgmUVNH4KEk7MFXlLeUE6XYlxMf1tKaQZ0E8fpPPH3L4= Message-ID: From: "Alan Melia" To: References: <56365650.1080701@gmail.com><85196BC78CF6472CAFCDEB70A7BFD6A7@gnat> Date: Sun, 1 Nov 2015 21:58:06 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5931 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6157 X-Scan-Signature: 3d57f46aaa11dced1062afcdaf02fb40 Subject: Re: LF: RTE 252kHz Content-Type: multipart/alternative; boundary="----=_NextPart_000_00DE_01D114F0.639AC910" 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: 4780 This is a multi-part message in MIME format. ------=_NextPart_000_00DE_01D114F0.639AC910 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Hi Andy, maybe or maybe not. I did detect a "breathing effect" of a few = parts in 10^11 soon after the synth was replaced at Droitwich. At this = level I was not sure of my own stadard's stability which was a pair of = Austron 1250a DOCXOs which have a short term stability of 1in 10^12 0ver = a couple of minutes. Well the 'ZAZ is a FLL not a PLL :-)) Alan G3NYK ----- Original Message -----=20 From: Andy Talbot=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Sunday, November 01, 2015 9:07 PM Subject: Re: LF: RTE 252kHz Confirmed. After 70 minutes of using the other GPSDO, the phase display of = Droitwich has remained in the same place - so subject to phase reading = accuracy, that is a frequency accuracy of a part or two in 10^-11 - = much more like it! =20 In fact, watching over a period of several minutes, its poorer short = term stability can be seen as small phase shifts that reverse back over = a few minutes - although that could also be caused by propagation, = perhaps ??? So the VE2ZAZ does need some doctoring and checking out - or = scrapping. 'jnt On 1 November 2015 at 19:55, Andy Talbot wrote: Yes, I think its the VE2ZAZ GPSDO here. MSF was showing 0.6PPB = frequency error too, so defintely the reference source I'm recalling that when tested before it was out by that sort of = order - its an odd beast, a frequency counter that prods the OCXO = periodically. Very long settling times. =20 I've just fired up an old Connor Winfield GPSDO . That's the short = time constant type of GPSDO, so ideal for LF use with long symbol = periods. Andy On 1 November 2015 at 19:39, Alan Melia = wrote: Hi Andy I havent checked recently but as far as I know NPL measure = Droitwich twice a day and post the tabulated results on their web = site.If they see a problem they contact the contractor (was Merlin = Communications) and a man gets on his bike from Coventry :-)). After my = reports and the subsequent synth failure a number of years back I think = Merlin, slightly embarassed bought themselves an off-air standard. = 0.6ppb is well inside the level that would get NPL ringing Merlin but = the "apparent reflection height" may still be rising at 1900z?? Alan G3NYK ----- Original Message -----=20 From: Andy Talbot=20 To: rsgb_lf_group@blacksheep.org ; = rsgb_lf_group@yahoogroups.co.uk=20 Sent: Sunday, November 01, 2015 7:00 PM Subject: Re: LF: RTE 252kHz Hi All - =20 Its no good at this stage looking for small signals. All I'm = trying to do is prove the HARDWARE. At the moment I have a QSD type = receiver delivering a signal centred on 1kHz. This is bandpass = filtered to about 100Hz bandwidth, then I/Q sampled at 1kHz sampling = rate to deliver 12 bit baseband values at 1kHz At the moment all I'm doing with these is displaying them on a = vectorscope plot - like that shown in the attachment - in order to prove = phase coherency of the system. So only strong signals are acceptable at = this stage - decimation and narrowband filtering can come later - that = is high level software and easier to implement And I've discovered something that needs explaining. Having = just been monitoring Droitwich on 198kHz for the last couple of hours, = its phase plot indicates drift of 300 degrees in that time. Expressed = in terms of a frequency offset that is 0.00012Hz, or 0.6 PPB at 198kHz. Now : My reference is a VE2ZAZ GPSDO which is long term spot on, but = subject to short term variations. I have to check if it remains better = than 0.6PPB over that period. The VE2ZAZ isn't my favourite solution = for LF working. But a local high standard frequency reference isn't an = issue - the Caesium tube can be turned on to solve that one! The LO in the LF receiver is a DDS tuned by a rotary encoder. = The PIC maths was written from first principles using 64 x 64 bit = integer arithmetic, BUT the pre-stored -constants to start with were = evaluated via a spreadsheet - which I'm not convinced provides = sufficient numerical accuracy to simulate the maths resolution needed to = get teh constantsin teh first place. So that needs checking. And, of course, although Droitwich is supposed to be a = frequency standard, it is only Rubidium controlled; set manually from = "time to time" against an on site Caesium source. 0.6 PPB is of the = order of a Rb source that hasn't been corrected for a while. Is = Droitwich properly maintained these days when very few people want it as = a reference? can we really assume its good enough? I've now changed to monitoring MSF 60kHz so lets see what = indicted drift that shows - its reasonable to assume that really is = good! Checking the constants used in the arithmetic is the most = difficult task. My high level programming language only offer up to 64 = bit integers, so the multiplication used in the PIC cannot be simulated = exactly in a prog, meaning I need to work with double precision floats = and cast to integers as and when. Andy G4JNT On 1 November 2015 at 18:13, IZ7SLZ = wrote: On 11/1/2015 4:17 PM, Andy Talbot wrote: Oh well... Still searching for a clean MF carrier Andy G4JNt Hello Andy, and all i'm now putting a small signal on 478502.24 Hz in opera8 mode. = Tx is GPS-locked. It is the same TX exciter that i used in EbNaut = experiment weeks ago. Maybe this signal is useful for your receiver test. All the best. 73, Domenico / iz7slz ------=_NextPart_000_00DE_01D114F0.639AC910 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable =EF=BB=BF
Hi Andy, maybe or maybe not. I did = detect a=20 "breathing effect" of a few parts in 10^11 soon after the synth was = replaced at=20 Droitwich. At this level I was not sure of my own stadard's = stability which=20 was a pair of Austron 1250a DOCXOs which have a short term = stability of 1in=20 10^12 0ver a couple of minutes.
 
Well the 'ZAZ is a FLL not a PLL = :-))
 
Alan
G3NYK
 
----- Original Message -----
From:=20 Andy=20 Talbot
Sent: Sunday, November 01, 2015 = 9:07=20 PM
Subject: Re: LF: RTE = 252kHz

Confirmed.
After 70 minutes of using the other GPSDO, the phase display of = Droitwich=20 has remained in the same place - so subject to phase reading accuracy, = that is=20 a frequency accuracy of a  part or two in 10^-11 - much more like = it!=20  

In fact, watching over a period of several minutes, its poorer = short term=20 stability can be seen as small phase shifts that reverse back over a = few=20 minutes - although that could also be caused by propagation, perhaps = ???

So the VE2ZAZ does need some doctoring and checking out - or=20 scrapping.

'jnt





On 1 November 2015 at 19:55, Andy Talbot = <andy.g4jnt@gmail.com> wrote:
Yes, I think its the VE2ZAZ GPSDO here.   MSF = was showing=20 0.6PPB frequency error too, so defintely the reference source
 I'm recalling that when tested before it was out by that = sort of=20 order - its an odd beast, a frequency counter that prods the OCXO=20 periodically.   Very long settling times.   

I've just fired up an old Connor Winfield GPSDO .  That's = the=20 short time constant type of GPSDO, so ideal for LF use with long = symbol=20 periods.

Andy


On 1 November 2015 at 19:39, Alan Melia = <alan.melia@btinternet.com> wrote:
Hi Andy I havent checked recently = but as far=20 as I know NPL measure Droitwich twice a day and post the tabulated = results=20 on their web site.If they see a problem they contact the = contractor (was=20 Merlin Communications) and a man gets on his bike from Coventry = :-)).=20 After my reports and the subsequent synth failure a number of = years back I=20 think Merlin, slightly embarassed bought themselves an off-air = standard.=20 0.6ppb is well inside the level that would get NPL ringing Merlin = but the=20 "apparent reflection height" may still be rising at = 1900z??
 
Alan
G3NYK
----- Original Message ----- =
From: Andy Talbot
To: rsgb_lf_group@blacksheep.org ; rsgb_lf_group@yahoogroups.co.uk
Sent: Sunday, November = 01, 2015=20 7:00 PM
Subject: Re: LF: RTE = 252kHz

Hi All - =20

Its no good at this stage looking for small signals.  = All I'm=20 trying to do is prove the HARDWARE.  At the moment I have a = QSD=20 type receiver delivering a signal centred on 1kHz.   =  This is=20 bandpass filtered to about 100Hz bandwidth, then I/Q sampled at = 1kHz=20 sampling rate to deliver 12 bit baseband values at 1kHz

At the moment all I'm doing with these is  displaying = them on=20 a vectorscope plot - like that shown in the attachment - in = order to=20 prove phase coherency of the system.  So only strong = signals are=20 acceptable at this stage - decimation and narrowband filtering = can come=20 later - that is high level software and easier to = implement

And I've discovered something that needs explaining.  = Having=20 just been monitoring Droitwich on 198kHz for the last couple of = hours,=20 its phase plot indicates drift of 300 degrees in that time. =  =20 Expressed in terms of a frequency offset that is 0.00012Hz, or = 0.6 PPB=20 at 198kHz.

Now :
My reference is a VE2ZAZ GPSDO which is long term spot on, = but=20 subject to short term variations.   I have to check if it = remains=20 better than 0.6PPB over that period.    The VE2ZAZ = isn't my=20 favourite solution for LF working.  But a local high = standard=20 frequency reference isn't an issue - the Caesium tube can be = turned on=20 to solve that one!

The LO in the LF receiver is a DDS tuned by a rotary = encoder.=20    The PIC maths was written from first principles = using 64 x=20 64 bit integer arithmetic, BUT the pre-stored -constants to = start with=20 were evaluated via a spreadsheet - which I'm not convinced = provides=20 sufficient numerical accuracy to simulate the maths resolution = needed to=20 get teh constantsin teh first place.   So that needs=20 checking.

And, of course,   although Droitwich is supposed to be = a=20 frequency standard, it is only Rubidium controlled; set manually = from=20 "time to time" against an on site Caesium source.  0.6 PPB = is of=20 the order of a Rb source that hasn't been corrected for a while. =  =20 Is Droitwich properly maintained these days when very few people = want it=20 as a reference?  can we really assume its good = enough?

I've now changed to monitoring MSF 60kHz so lets see what = indicted=20 drift that shows - its reasonable to assume that really is = good!

Checking the constants used in the arithmetic is the most = difficult=20 task.  My high level programming language only offer up to = 64 bit=20 integers, so the multiplication used in the PIC cannot be = simulated=20 exactly in a prog, meaning I need to work with double precision = floats=20 and cast to integers as and when.

Andy  G4JNT

On 1 November 2015 at 18:13, IZ7SLZ = <iz7slz.domenico@gmail.com> = wrote:
On 11/1/2015 4:17 PM, Andy Talbot wrote:
Oh well...

Still searching for a = clean MF=20 carrier

Andy  =  G4JNt


Hello=20 Andy, and all

i'm now putting a small signal on = 478502.24 Hz in=20 opera8 mode. Tx is GPS-locked. It is the same TX exciter that = i used=20 in EbNaut experiment  weeks ago.
Maybe this signal is = useful=20 for your receiver test.

All the best.

73, = Domenico /=20 = iz7slz




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