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=2.1 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, FORGED_MUA_OUTLOOK,HTML_30_40,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 tA1Jhhsf014848 for ; Sun, 1 Nov 2015 20:43:43 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1ZsyUf-0004Sz-3A for rs_out_1@blacksheep.org; Sun, 01 Nov 2015 19:40:45 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1ZsyUe-0004Sq-Mm for rsgb_lf_group@blacksheep.org; Sun, 01 Nov 2015 19:40:44 +0000 Received: from rgout04.bt.lon5.cpcloud.co.uk ([65.20.0.181]) by relay1.thorcom.net with esmtp (Exim 4.86) (envelope-from ) id 1ZsyTe-0006px-Oz for rsgb_lf_group@blacksheep.org; Sun, 01 Nov 2015 19:40:43 +0000 X-OWM-Source-IP: 86.178.169.152 (GB) X-OWM-Env-Sender: alan.melia@btinternet.com X-CTCH-RefID: str=0001.0A090203.56366A70.0007,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=2.7.2:2015.10.14.125417:17:39.532,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, BODYTEXTH_SIZE_10000_LESS, __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 rgout04.bt.lon5.cpcloud.co.uk (8.6.122.06) (authenticated as alan.melia@btinternet.com) id 561CE904022C62B4 for rsgb_lf_group@blacksheep.org; Sun, 1 Nov 2015 19:38:48 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=btinternet.com; s=btcpcloud; t=1446406743; bh=YrlZdSH2XkcbrdUkrTdi+GIXqgaS2miXWg8zZLWCQW4=; h=Message-ID:From:To:References:Subject:Date:MIME-Version:X-Mailer; b=rYXqEMSryYJSrm0FtJaW3pf1qVV3zDLcF2P5Gm6EdF86tgqVHQ8j85YFNMubu9x49chHvUuG92UTMIw6/VNJLNR9xEir4n/kBm1k8tqK5lReOI6MI0gzhL9xL3WfIj6OQL9nuBAqTnEqzsv0HUBnm9RKOBPhkT5slWHCu8XuZ48= Message-ID: <85196BC78CF6472CAFCDEB70A7BFD6A7@gnat> From: "Alan Melia" To: References: <56365650.1080701@gmail.com> Date: Sun, 1 Nov 2015 19:39:24 -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: 7574eaf38ab90cf371fa9661dd9329b0 Subject: Re: LF: RTE 252kHz Content-Type: multipart/alternative; boundary="----=_NextPart_000_00BE_01D114DD.0357D1F0" 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: 4772 This is a multi-part message in MIME format. ------=_NextPart_000_00BE_01D114DD.0357D1F0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable 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_00BE_01D114DD.0357D1F0 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable =EF=BB=BF
Hi Andy I havent checked recently but = as far as I=20 know NPL measure Droitwich twice a day and post the tabulated results on = their=20 web site.If they see a problem they contact the contractor (was Merlin=20 Communications) and a man gets on his bike from Coventry :-)). After my = reports=20 and the subsequent synth failure a number of years back I think Merlin, = slightly=20 embarassed bought themselves an off-air standard. 0.6ppb is well inside = the=20 level that would get NPL ringing Merlin but the "apparent reflection = height" may=20 still be rising at 1900z??
 
Alan
G3NYK
----- Original Message -----
From:=20 Andy=20 Talbot
Sent: Sunday, November 01, 2015 = 7:00=20 PM
Subject: Re: LF: RTE = 252kHz

Hi All - 

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

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

And I've discovered something that needs explaining.  Having = just=20 been monitoring Droitwich on 198kHz for the last couple of hours, its = phase=20 plot indicates drift of 300 degrees in that time.   Expressed in = terms of=20 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=20 short term variations.   I have to check if it remains better = than 0.6PPB=20 over that period.    The VE2ZAZ isn't my favourite solution = for LF=20 working.  But a local high standard frequency reference isn't an = issue -=20 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. =  =20  The PIC maths was written from first principles using 64 x 64 = bit=20 integer arithmetic, BUT the pre-stored -constants to start with were = evaluated=20 via a spreadsheet - which I'm not convinced provides sufficient = numerical=20 accuracy to simulate the maths resolution needed to get teh = constantsin teh=20 first place.   So that needs checking.

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

I've now changed to monitoring MSF 60kHz so lets see what = indicted drift=20 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 = integers, so the multiplication used in the PIC cannot be simulated = exactly in=20 a prog, meaning I need to work with double precision floats and cast = to=20 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 = carrier

Andy  =  G4JNt


Hello Andy,=20 and all

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

All the best.

73, Domenico /=20 iz7slz


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