Return-Path: X-Spam-DCC: paranoid 1290; 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=-0.5 required=5.0 tests=BAYES_00,FORGED_AOL_TAGS, HTML_40_50,HTML_MESSAGE,UNPARSEABLE_RELAY 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 sB1EAoxC002325 for ; Mon, 1 Dec 2014 15:10:51 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1XvRaP-0005s0-DQ for rs_out_1@blacksheep.org; Mon, 01 Dec 2014 14:04:21 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1XvRaO-0005rr-Qv for rsgb_lf_group@blacksheep.org; Mon, 01 Dec 2014 14:04:20 +0000 Received: from omr-m05.mx.aol.com ([64.12.143.79]) by relay1.thorcom.net with esmtps (TLSv1:DHE-RSA-AES256-SHA:256) (Exim 4.84) (envelope-from ) id 1XvRaL-00072Z-1c for rsgb_lf_group@blacksheep.org; Mon, 01 Dec 2014 14:04:19 +0000 Received: from mtaomg-mcd02.mx.aol.com (mtaomg-mcd02.mx.aol.com [172.26.223.208]) by omr-m05.mx.aol.com (Outbound Mail Relay) with ESMTP id 8781C703A02A3 for ; Mon, 1 Dec 2014 09:04:14 -0500 (EST) Received: from core-afa10h.mail.aol.com (core-afa10.mail.aol.com [172.27.24.10]) by mtaomg-mcd02.mx.aol.com (OMAG/Core Interface) with ESMTP id EF4C83800008B for ; Mon, 1 Dec 2014 09:04:12 -0500 (EST) To: rsgb_lf_group@blacksheep.org X-MB-Message-Source: WebUI X-MB-Message-Type: User MIME-Version: 1.0 From: Markus Vester X-Mailer: AOL Webmail BASIC Received: from 194.138.39.54 by webmail-vm015.sysops.aol.com (64.12.251.120) with HTTP (WebMailUI); Mon, 01 Dec 2014 09:04:10 -0500 Message-Id: <8D1DB86D02874AB-12B4-3D493@webmail-vm015.sysops.aol.com> X-Originating-IP: [194.138.39.54] Date: Mon, 1 Dec 2014 09:04:10 -0500 x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20140625; t=1417442654; bh=hKEBFQI/YHuaT4Xo+qcZqFbN58ho1inDnnvNarl2nUk=; h=From:To:Subject:Message-Id:Date:MIME-Version:Content-Type; b=JI7judgcm3XJ7QMKE4cqh64t6D3YeQ45OBJtmdHKOQoLY7qh0uebG4fAVqi7x12n/ qAEeGsPfcyU0Z6jGRxQu/wZ5NF6lFUSUJaT3dczW47S9FPLjlZBZyTrcQEfs+zU0z1 lLxQOJB61wb0cTzAPcvil79HgVBKXzmMb/ZqShVg= x-aol-sid: 3039ac1adfd0547c755c1428 X-Scan-Signature: fe104f0109b1b9777bcb4182b547ef25 Subject: Re: VLF: Experiments - anyone? Content-Type: multipart/alternative; boundary="--------MB_8D1DB86D068B4BB_12B4_A0AD2_webmail-vm015.sysops.aol.com" 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: 1373 This is a multi-part message in MIME format. ----------MB_8D1DB86D068B4BB_12B4_A0AD2_webmail-vm015.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" =C2=A0Hi=20Warren,=20Paul,=0D=0A=C2=A0=0D=0AI'm=20pasting=20two=20earlier=20mail= s=20to=20the=20group=20and=20to=20Dex,=20which=20should=20give=20an=20idea=20of=20= the=20transmit=20setup=20using=20Paul's=20FEC-encoded=20BPSK.=0D=0A=C2=A0=0D=0AB= est=2073,=0D=0AMarkus=20(DF6NM)=0D=0A=0D=0AVon:=20Paul=20Nicholson=20<vlf0403= @abelian.org>=0D=0AAn:=20rsgb_lf_group=20<rsgb_lf_group@blacksheep.org>= =0D=0AVerschickt:=20Mo,=201=20Dez=202014=209:25=20am=0D=0ABetreff:=20Re:=20VLF:=20= Experiments=20-=20anyone?=0D=0A=0D=0A...=0D=0AI=20think=20so,=20Markus=20devised= =20a=20way=20to=20send=20an=20encoded=20message=20=0D=0Ausing=20Spectrum=20Lab.=C2= =A0=20It=20is=20necessary=20to=20arrange=20something=20like=20a=20=0D=0ADPDT=20r= elay=20to=20reverse=20the=20phase=20of=20the=20tx=20signal=20under=20control=20=0D= =0Aof=20Spectrum=20Lab.=C2=A0=20The=20PC=20needs=20reasonably=20good=20clock=20d= iscipline=20=0D=0A(0.1=20seconds=20or=20so)=20so=20that=20the=20bits=20are=20syn= chronous=20with=20UT=20=0D=0Aand=20the=20carrier=20has=20to=20be=20GPS=20or=20Ru= bidium=20locked,=20or=20maybe=20=0D=0Afrom=20a=20very=20good=20OCXO.=20=0D=0A=20= =0D=0AI'll=20dig=20out=20the=20details=20in=20a=20follow-up.=20=0D=0A--=20=0D=0A= Paul=20Nicholson=20=0D=0A--=C2=A0=0D=0A=20=0D=0A-----Urspr=C3=BCngliche=20Mittei= lung-----=20=0D=0AVon:=20Markus=20Vester=20<markusvester@aol.com>=0D=0AAn:= =20dexter.mc=20<dexter.mc@gmail.com>=0D=0ACc:=20Paul=20Nicholson=20<vlf= 0403@abelian.org>=0D=0AVerschickt:=20Mo,=202=20Jun=202014=2011:30=20pm=0D=0AB= etreff:=20Re:=208971=20khz=20-=20SpecLab=20setup=20for=20PSK=20drive=0D=0A=0D=0A= Hi=20Dex,=0D=0A=C2=A0=0D=0AI'll=20try=20to=20give=20some=20hints=20regarding=20s= peclab=20setup=20=20for=20binary=20audio=20output.=0D=0A=C2=A0=0D=0AFirst=20you'= ll=20need=20to=20encode=C2=A0your=20text=20=20message=C2=A0using=20Paul's=20web=20= script=20http://abelian.org/fec/encode.cgi=C2=A0.=C2=A0Let=20=20Paul=20suggest=C2= =A0an=20encoding=20(probably=20either=20r=201/8=20K=3D25=20or=C2=A0r=201/16=20K=3D= 25),=20=20a=20symbol=20duration=20(eg.=2030=20seconds),=20and=20a=20UTC=20start=20= time.=20Copy=20and=20paste=20the=20=20resulting=C2=A0binary=20sequence=C2=A0to=20= a=20text=20file.=0D=0A=C2=A0=0D=0ATo=20setup=20SpecLab,=20you=20can=20start=20fr= om=C2=A0a=20config=20=20file=20which=C2=A0was=20derived=20from=20my=C2=A0current= =20VLF=20grabber.=20=0D=0Ahttp://dl.dropboxusercontent.com/u/26404526/_vlf_wide_= twoloops_tx-psk-30s_140602.USR=0D=0Ahttp://dl.dropboxusercontent.com/u/26404526/= SpecLab_setup_to_send_binary_sequence.png=0D=0AYou=20can=20ignore=20or=20disable= =20all=C2=A0that=20stereo=20=20receive=20stuff.=20All=20that's=20needed=20is=C2=A0= a=20digimode=20terminal=20instance,=20=20which=C2=A0should=20be=C2=A0configured=C2= =A0as=20shown=20on=20the=20right=C2=A0of=20the=20=20screenshot.=20Important=20en= tries=20are=20Encoding:=20None=20(one-to-one)=20and=20the=20speed=20=20setting,=20= eg.=200.0333=20sym/sec.=20Then=20you=20can=20load=20the=20prepared=20text=20file= =20to=20the=20TX=20=20window,=20but=20don't=20press=20the=20big=20TX=20(red)=20-= =20RX=20(green)=20-=20OFf=20(grey)=20button=20=20yet.=0D=0A=C2=A0=0D=0AThe=20tra= nsmission=C2=A0should=20be=20initiated=20=20automatically=C2=A0from=20the=C2=A0s= cheduled=20actions=20tab=20(top=20left),=20issuing=20the=20=20di.tx("")=20comman= d=20precisely=20at=20the=20assigned=20sequence=20start=20time=20(eg.=205:00=20UT= ).=20=20This=20will=20then=20activate=20the=20dormant=20digimode=20terminal=20on= =20time,=20based=20on=20the=20PC=20=20clock=20which=20should=20be=20kept=C2=A0to= =20UTC=C2=A0by=20some=20NTP=20tool.=0D=0A=C2=A0=0D=0AThe=20audio=20output=20from= =20the=20soundcard=20will=20be=20on-off=20=20keyed=20dashes=20at=20eg.=201300=20= Hz,=20which=20can=20simply=20be=20rectified=20to=20drive=20a=20small=20=20relay,= =20commuting=20between=200=C2=B0=20and=20180=C2=B0=20outputs=20of=20a=20small=20= transformer:=20=20http://df6nm.bplaced.net/VLF/pictures/VLF_PSK_140510/psk_relay= .jpg=0D=0A=C2=A0=0D=0AGood=20luck!=0D=0AMarkus=0D=0A=C2=A0=0D=0A=0D=0A=0D=0A=0D=0A= -----Urspr=C3=BCngliche=20Mitteilung-----=20=0D=0AVon:=20Markus=20Vester=20<m= arkusvester@aol.com>=0D=0AAn:=20rsgb_lf_group=20<rsgb_lf_group@blacksheep.= org>=0D=0AVerschickt:=20So,=2011=20Mai=202014=2012:11=20pm=0D=0ABetreff:=20Re= :=20VLF:=20Coherent=20BPSK=20at=208270=20from=20DF6NM=0D=0A=C2=A0=20=20=20=20=20= =20=20Thanks=20Paul,=20for=20devising=20this=20experiment=20in=20the=20first=20p= lace,=C2=A0and=20encouraging=20me=20to=20take=20=20part=20in=20it.=20It=20looks=C2= =A0like=20we=20are=20now=20getting=C2=A0real=20close=20to=20the=20ultimate=20Sha= nnon=20limit,=20making=20best=20use=20of=20your=20=20superb=20receive=20capabili= ties.=0D=0A=0D=0A=20=20=C2=A0=0D=0A=20=20The=20transmit=20hardware=20setup=C2=A0= is=20similar=20to=20the=20=20previously=20used=20one,=20with=20a=20couple=20of=20= minor=20extensions.=20Here=20are=20some=20=20pictures:=20df6nm.bplaced.net/VLF/p= ictures/VLF_PSK_140510/=C2=A0=0D=0A=0D=0A=20=C2=A0=0D=0A=20The=208270=20Hz=20car= rier=C2=A0comes=20from=20a=20=20Rubidium-referenced=20decadic=20synthesizer,=20w= ith=20frequency=20calibrated=20to=20=20Loran-C=C2=A0to=20within=20about=201e-10.= =20For=20the=20test,=20an=20encoded=20bit=20sequence=20for=20the=20five-characte= r=20message=20=20was=C2=A0obtained=20beforehand=20from=20Paul's=20script=C2=A0on= =20his=20=20website.=C2=A0SpecLab's=20digimode=20terminal=20(configured=20simila= r=20as=C2=A0previously=20=20for=20Opera,=20and=20initiated=20by=20"scheduled=20a= ctions")=C2=A0is=20used=20to=20generate=20a=20=20keyed=20sidetone,=20with=20bit=20= timing=20controlled=20by=20NTP=20to=20within=20a=20second.=20=20The=20tone=20is=20= being=20rectified=20at=20the=20soundcard=20=20output=20and=20drives=20an=20ancie= nt=20and=20sensitive=C2=A0telephone=C2=A0relay,=20commuting=20=20the=C2=A0carrie= r=20between=20two=20complimentary=20outputs=20of=20a=20small=20pot=20core=20=20t= ransformer.=0D=0A=20=C2=A0=0D=0A=20The=20phase-keyed=20signal=20is=20then=20ampl= ified=20=20by=C2=A0the=20usual=C2=A0"Nitro"=20audio=20PA=20to=20about=2060=20Wat= ts=20(28=20V=20=20rms).=C2=A0A=C2=A0large=C2=A0ferrite=20transformer=20(in=20the= =20brown=20chocolate=20=20box)=C2=A0bought=20the=C2=A0voltage=20up=20to=C2=A0200= =20V=20rms,=C2=A0feeding=200.3=20A=20=20antenna=20current=20to=20the=20venerable= =20seven-bucket=20coil=20which=20is=C2=A0sitting=C2=A0in=20=20the=20blue=20rubbe= r=20bins=20outside=20the=20window.=0D=0A=20=C2=A0=0D=0A=20To=20keep=20the=20ante= nna=20on=20resonance,=20the=20phase=20=20detector=C2=A0from=20my=20LF=20automati= c=20tuner=20(basically=20an=20XOR=20comparing=20the=20phase=20=20of=20voltage=20= and=20current,=C2=A0with=20sensors=20modified=20for=C2=A0the=20lower=20frequency= )=20=20was=20inserted=20between=20the=20amp=20and=20the=20transformer.=C2=A0It=20= drives=20a=20little=20DC=20motor,=C2=A0pulling=20on=20a=20nylon=20string,=20whic= h=20then=20=20rotates=20a=2010x10x0.5=20cm^3=20ferrite=20plate=20inside=20the=C2= =A0coil.=20=20This=C2=A0effectively=20mitigates=20current=20reductions=20and=C2=A0= phase=20variations=20=20caused=20by=20wind,=20temperature=20and=20humidity.=20Du= ring=20=20operation,=C2=A0one=20can=20hear=20the=20whistle=20of=20the=20coil=20a= nd=20transformers,=20=20occasionally=20interrupted=20by=20a=20short=20"krk"=20so= und=20when=20the=20relay=20is=20bouncing=20=20during=20phase=20changes=20at=20fu= ll=20or=20half=20minute.=0D=0A=20=C2=A0=0D=0A=20=20All=20the=20best,=0D=0A=2073,= =20Markus=20(DF6NM)=0D=0A=0D=0A=20=0D=0A=C2=A0=0D=0A=0D=0A=20=20=20From:=20Paul=20= Nicholson=20=0D=0A=20Sent:=20Sunday,=20May=2011,=202014=208:36=20AM=0D=0A=20To:=20= rsgb_lf_group@blacksheep.org=20=20=0D=0A=20Subject:=20VLF:=20Coherent=20BPSK=20a= t=208270=20from=20DF6NM=0D=0A=0D=0A=0D=0A=20=0D=0A=0D=0AI=20=20am=20pleased=20to= =20report=20reception=20of=20two=20test=20transmissions=20from=0D=0ADF6NM=20on=20= =208270.000=20Hz=20which=20took=20place=20on=20Saturday=202014-05-10=0D=0Amornin= g.=0D=0A=0D=0AMarkus=20=20was=20sending=20coherent=20BPSK=20with=20UT=20synchron= ous=20symbols=0D=0Ausing=20a=20symbol=20period=20=20of=2030=20seconds.=C2=A0=20T= he=20FEC=20is=20a=20terminated=20rate=0D=0A1/4=20convolutional=20code=20with=20=20= constraint=20length=2021,=20cascaded=0D=0Awith=20an=20outer=20error=20detecting=20= code=20using=20a=2016=20=20bit=20CRC.=0D=0A=0D=0ATwo=20transmissions=20of=2046=20= bits=20were=20made,=20each=20lasting=20=20132=0D=0Aminutes=20with=20a=2020=20min= ute=20carrier=20test=20in=20between.=C2=A0=20ERP=20=20was=0D=0Aprobably=20around= =205=20or=2010=20uW=20and=20the=20range=20is=201028=20km.=0D=0A=0D=0AEb/N0=20was= =20=20about=20-0.5dB=20in=20the=20first=20test=20and=20about=20-1.5=20dB=0D=0Ain= =20the=20second,=20which=20is=20=20below=20-7dB=20in=20the=20symbol=20bandwidth=0D= =0Aof=2033.3=20mHz.=0D=0A=0D=0ABoth=20messages=20were=20=20decoded=20with=20some= =20margin=20to=20spare.=0D=0A=0D=0AThe=20decoder=20is=20a=20list=20Viterbi=20dec= oder=20=20using=20the=20tree=20trellis=0D=0Aalgorithm=20with=20a=20list=20length= =20of=202000=20and=20stack=20size=20=2020000.=0D=0ABoth=20messages=20decoded=20a= t=20the=20top=20of=20the=20list=20so=20the=20list=0D=0Adecoding=20=20wasn't=20ac= tually=20necessary=20for=20this=20strength=20of=20signal.=0D=0A=0D=0AThe=20trans= mitter=20=20uses=20a=20rubidium=20source=20and=20the=20receiver=20is=0D=0AGPS=20= timed.=C2=A0=C2=A0=20A=20reference=20=20phase=20at=20the=20receiver=20is=20obtai= ned=20by=0D=0Aaveraging=20the=20phase=20of=20the=20squared=20=20signal=20but=20a= t=20such=20low=20signal=0D=0Astrengths=20the=20resulting=20reference=20is=20unre= liable=20=20and=20the=20decoder=0D=0Amakes=20a=20search=20for=20the=20correct=20= phase=20and=20phase=20drift=20=20rate.=0D=0A=0D=0AThe=20signal=20is=20completely= =20invisible=20in=20any=20spectrogram=20at=20=20the=0D=0Areceiver.=C2=A0=C2=A0=20= In=20a=20spectrogram=20running=20at=20the=20symbol=20=20bandwidth=0D=0Athe=20sig= nal=20is=20too=20far=20below=20noise=20and=20the=20bandwidth=20of=20=20the=0D=0A= transmission=20is=20such=20that,=20in=20a=20resolution=20capable=20of=20seeing=0D= =0Athe=20=20signal=20above=20noise,=20the=20signal=20is=20too=20wide.=0D=0A=0D=0A= For=20example,=20this=20spectrogram=20=20uses=20the=20symbol=20bandwidth,=0D=0A=0D= =0A=C2=A0=20http://abelian.org/vlf/tmp/df6nm_140510a.png=0D=0A=0D=0AMaybe=20=20s= omeone=20can=20see=20some=20very=20faint=20line=20at=208270.000=20?=0D=0A=0D=0AT= he=20first=20test=20ran=20=2007:02=20to=2009:12=20and=20the=20second=0D=0Afrom=20= 09:32=20to=2011:44.=C2=A0=C2=A0=20The=2020=20minute=20=20carrier=20in=20between=20= is=0D=0Aalso=20below=20noise=20at=20this=20resolution.=0D=0A=0D=0AFollowing=20=20= the=20second=20test,=20an=20hour=20of=20carrier=20is=20visible=20in=0D=0Athe=202= 78=20uHz=20spectrogram=20=20at=0D=0A=0D=0A=C2=A0=20http://abelian.org/vlf/fbins.= shtml#p=3D1399780800&b=3D110&s=3Dsp=0D=0A=0D=0AMore=20=20information=20on=20the=20= FEC=20codes,=20trials,=20and=20search=20for=0D=0Agood=20polynomials=20can=20be=20= =20found=20at=0D=0A=0D=0A=C2=A0=20http://abelian.org/fec=0D=0A=0D=0AStronger=20c= odes=20=20with=20constraint=20length=20up=20to=2025=20are=20available=0D=0Aand=20= hopefully=20further=20tests=20=20will=20be=20made=20soon.=0D=0A--=0D=0APaul=20Ni= cholson=0D=0A--=0D=0A=0D=0A=20=20=0D=0A=20=0A=0A ----------MB_8D1DB86D068B4BB_12B4_A0AD2_webmail-vm015.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset="utf-8" =0D=0A=0D=0A=0D=0A
 H= i=20Warren,=20Paul,
=0D=0A=0D=0A
 
=0D=0A=0D=0A
I'm=20pas= ting=20two=20earlier=20mails=20to=20the=20group=20and=20to=20Dex,=20which=20shou= ld=20give=20an=20idea=20of=20the=20transmit=20setup=20using=20Paul's=20FEC-encod= ed=20BPSK.
=0D=0A=0D=0A
 
=0D=0A=0D=0A
Best=2073,
=0D= =0A=0D=0A
Markus=20(DF6NM)
=0D=0A
=0D=0AVon:=20Paul=20Nicholson=20<= vlf0403@abelian.org>
=0D=0AAn:=20rsgb_lf_group=20<rsgb_lf_group@blacksh= eep.org>
=0D=0AVerschickt:=20Mo,=201=20Dez=202014=209:25=20am
=0D=0ABet= reff:=20Re:=20VLF:=20Experiments=20-=20anyone?
=0D=0A
=0D=0A=0D=0A
.= ..
=0D=0A=0D=0A
I=20think=20so,=20Markus=20devised=20a=20way=20to=20sen= d=20an=20encoded=20message=20
=0D=0Ausing=20Spectrum=20Lab. =20It=20is=20= necessary=20to=20arrange=20something=20like=20a=20
=0D=0ADPDT=20relay=20to=20= reverse=20the=20phase=20of=20the=20tx=20signal=20under=20control=20
=0D=0Aof=20= Spectrum=20Lab. =20The=20PC=20needs=20reasonably=20good=20clock=20disciplin= e=20
=0D=0A(0.1=20seconds=20or=20so)=20so=20that=20the=20bits=20are=20synchro= nous=20with=20UT=20
=0D=0Aand=20the=20carrier=20has=20to=20be=20GPS=20or=20Ru= bidium=20locked,=20or=20maybe=20
=0D=0Afrom=20a=20very=20good=20OCXO.=20
=0D= =0A=20
=0D=0AI'll=20dig=20out=20the=20details=20in=20a=20follow-up.=20
=0D= =0A--=20
=0D=0APaul=20Nicholson=20
=0D=0A-- 
=0D=0A=20
=0D=0A= =0D=0A
-----Urspr=C3=BCngliche=20Mitteilung-----=20
=0D=0AVon:=20Markus=20= Vester=20<markusvester@aol.com>
=0D=0AAn:=20dexter.mc=20<dexter.mc@g= mail.com>
=0D=0ACc:=20Paul=20Nicholson=20<vlf0403@abelian.org>
=0D= =0AVerschickt:=20Mo,=202=20Jun=202014=2011:30=20pm
=0D=0ABetreff:=20Re:=20897= 1=20khz=20-=20SpecLab=20setup=20for=20PSK=20drive
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=0D=0A=0D=0A=0D=0A=0D=0A
= Hi=20Dex,
=0D=0A=0D=0A
 
=0D=0A=0D=0A
I'll=20try=20to=20give=20some=20hints=20regarding=20speclab= =20setup=20=20for=20binary=20audio=20output.
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=0D=0A=0D=0A
First=20you'll=20need=20to=20encode your=20text=20=20me= ssage using=20Paul's=20web=20script=20http://abelian.org/fec/e= ncode.cgi . Let=20=20Paul=20suggest an=20encoding=20(probably= =20either=20r=201/8=20K=3D25=20or r=201/16=20K=3D25),=20=20a=20symbol=20dur= ation=20(eg.=2030=20seconds),=20and=20a=20UTC=20start=20time.=20Copy=20and=20pas= te=20the=20=20resulting binary=20sequence to=20a=20text=20file.=
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=0D= =0A=0D=0A
To=20setup=20SpecLab,=20you=20= can=20start=20from a=20config=20=20file=20which was=20derived=20from=20= my current=20VLF=20grabber.=20
=0D=0A=0D=0A
http://dl.dropboxuserco= ntent.com/u/26404526/_vlf_wide_twoloops_tx-psk-30s_140602.USR
=0D= =0A=0D=0A
http://dl.dropboxusercontent.com/u/26404526/SpecLab_setup_to_send_binary= _sequence.png
=0D=0A=0D=0A
You=20can=20ignore=20or=20disable=20all that=20stereo=20=20receive=20stu= ff.=20All=20that's=20needed=20is a=20digimode=20terminal=20instance,=20=20w= hich should=20be configured as=20shown=20on=20the=20right of= =20the=20=20screenshot.=20Important=20entries=20are=20Encoding:=20None=20(one-to= -one)=20and=20the=20speed=20=20setting,=20eg.=200.0333=20sym/sec.=20Then=20you=20= can=20load=20the=20prepared=20text=20file=20to=20the=20TX=20=20window,=20but=20d= on't=20press=20the=20big=20TX=20(red)=20-=20RX=20(green)=20-=20OFf=20(grey)=20bu= tton=20=20yet.
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=  
=0D=0A=0D=0A
The=20tr= ansmission should=20be=20initiated=20=20automatically from=20the = scheduled=20actions=20tab=20(top=20left),=20issuing=20the=20=20di.tx("")=20comma= nd=20precisely=20at=20the=20assigned=20sequence=20start=20time=20(eg.=205:00=20U= T).=20=20This=20will=20then=20activate=20the=20dormant=20digimode=20terminal=20o= n=20time,=20based=20on=20the=20PC=20=20clock=20which=20should=20be=20kept t= o=20UTC by=20some=20NTP=20tool.
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=0D=0A=0D=0A
The=20audio=20output=20from=20the=20soundcard=20will=20be=20on-off=20= =20keyed=20dashes=20at=20eg.=201300=20Hz,=20which=20can=20simply=20be=20rectifie= d=20to=20drive=20a=20small=20=20relay,=20commuting=20between=200=C2=B0=20and=201= 80=C2=B0=20outputs=20of=20a=20small=20transformer:=20=20http://df6nm.bplaced.net/VLF/pictures/VLF_PSK_140510/psk_relay= .jpg
=0D=0A=0D=0A
 
=0D=0A=0D=0A
Good=20luck!
=0D=0A=0D=0A
Markus=0D=0A=0D=0A
 
=0D=0A=
=0D=0A
=0D=0A=0D=0A-----Urspr=C3=BCngliche=20Mitteilung-----=20=0D=0AVon:=20Markus=20Vester=20<markusvester@aol.com>
=0D=0AAn:=20rsg= b_lf_group=20<rsgb_lf_group@blacksheep.org>
=0D=0AVerschickt:=20So,=201= 1=20Mai=202014=2012:11=20pm
=0D=0ABetreff:=20Re:=20VLF:=20Coherent=20BPSK=20a= t=208270=20from=20DF6NM
=0D=0A =0D=0A=20=20=20=20=20=0D=0A=20=0D=0A
=20=0D=0A
Thanks=20= Paul,=20for=20devising=20this=20exper= iment=20in=20the=20first=20place, and=20encouraging=20me=20to=20take=20=20p= art=20in=20it.=20It=20looks like=20we=20are=20now=20getting real=20cl<= /font>ose=20to=20the=20ultimate=20Shannon=20= limit,=20making=20best=20use=20of=20your=20=20superb=20receive=20capabilities.
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=0D=0A=20=0D=0A
=20=0D=0A
 
=0D=0A=20=0D=0A
=20=0D=0A
The=20transmit=20hardware=20setup is=20similar=20to= =20the=20=20previously=20used=20one,=20with=20a=20couple=20of=20minor=20extensio= ns.=20Here=20are=20some=20=20pictures:=20df6nm.bplaced.ne= t/VLF/pictures/VLF_PSK_140510/ 
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=0D=0A=20=0D=0A
= The=208270=20Hz=20carrier comes=20from=20= a=20=20Rubidium-referenced=20decadic=20synthesizer,=20with=20frequency=20calibra= ted=20to=20=20Loran-C to=20within=20about=201e-10.=20For=20the=20test,=20a<= /font>n=20encoded=20bit=20sequence=20for=20t= he=20five-character=20message=20=20was obtained=20beforehand=20from=20Paul'= s=20script on=20his=20=20website. SpecLab's=20digimode=20terminal=20(c= onfigured=20similar=20as previously=20=20for=20Opera,=20and=20initiated=20b= y=20"scheduled=20actions") is=20used=20to=20generate=20a=20=20keyed=20sidet= one,=20with=20bit=20timing=20controlled=20by=20NTP=20to=20within=20a=20second.=20= =20The=20tone=20is=20being=20rectifie= d=20at=20the=20soundcard=20=20output=20and=20drives=20an=20ancient=20and=20sensi= tive telephone relay,=20commuting=20=20the carrier=20between=20tw= o=20complimentary=20outputs=20of=20a=20small=20pot=20core=20=20transformer.
=0D=0A=20=0D=0A
 
=0D=0A=20=0D=0A
The=20phase-keyed=20signal=20is=20then=20amplified=20=20by&= nbsp;the=20usual "Nitro"=20audio=20PA=20to=20about=2060=20Watts=20(28=20V=20= =20rms). A large ferrite=20transformer=20(in=20the=20brown=20choc= olate=20=20box) bought=20the voltage=20up=20to 200=20V=20rms,&nbs= p;feeding=200.3=20A=20=20antenna=20current=20to=20the=20venerable=20seven-bucket= =20coil=20which=20is sitting in=20=20the=20blue=20rubber=20bins=20outs= ide=20the=20window.
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=0D=0A=20=0D=0A
To=20keep=20the=20antenna=20on=20resonance,=20the=20phase=20=20detector = from=20my=20LF=20automatic=20tuner=20(basically=20an=20XOR=20comparing=20the=20p= hase=20=20of=20voltage=20and=20current, with=20sensors=20modified=20for&nbs= p;the=20lower=20frequency)=20=20was=20inserted=20between=20the=20amp=20and=20the= =20transformer. It=20drives=20a=20= little=20DC=20motor, pulling=20on=20a=20nylon=20string,=20which=20then=20=20= rotates=20a=2010x10x0.5=20cm^3=20ferrite=20plate=20inside=20the coil.=20=20= This effectively=20mitigates=20current=20reductions=20and phase=20vari= ations=20=20caused=20by=20wind,=20temperature=20and=20humidity.=20During=20=20operation, one=20can=20hear=20the=20= whistle=20of=20the=20coil=20and=20transformers,=20=20occasionally=20interrupted=20= by=20a=20short=20"krk"=20sound=20when=20the=20relay=20is=20bouncing=20=20during=20= phase=20changes=20at=20full=20or=20half=20minute.
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=0D=0A=20=0D=0A
=20= =0D=0A
All=20the=20best,
=0D= =0A=20=0D=0A
73,=20Markus=20(DF6NM)
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=0D=0A=20=0D=0A

=0D=0A 
=0D=0A=0D=0A=20=0D=0A=20=0D=0A= =20=0D=0AFrom:=20Paul=20Nicholson=20=0D=0A=20=0D=0A
Sent:=20Sunday,=20May=2011,=202014=208:36=20AM
=0D=0A=20=0D=0A
= To:=20rsgb_lf_group@blacksheep.org=20=20
=0D=0A=20=0D=0A=
Subject:=20VLF:=20Coherent=20BPSK=20at=208270=20from=20DF6NM
=0D= =0A=0D=0A=0D=0A=20=0D=0A

=0D=0A
=0D=0AI=20=20am=20= pleased=20to=20report=20reception=20of=20two=20test=20transmissions=20from
=0D= =0ADF6NM=20on=20=208270.000=20Hz=20which=20took=20place=20on=20Saturday=202014-0= 5-10
=0D=0Amorning.
=0D=0A
=0D=0AMarkus=20=20was=20sending=20coherent=20= BPSK=20with=20UT=20synchronous=20symbols
=0D=0Ausing=20a=20symbol=20period=20= =20of=2030=20seconds. =20The=20FEC=20is=20a=20terminated=20rate
=0D=0A1/= 4=20convolutional=20code=20with=20=20constraint=20length=2021,=20cascaded
=0D= =0Awith=20an=20outer=20error=20detecting=20code=20using=20a=2016=20=20bit=20CRC.=
=0D=0A
=0D=0ATwo=20transmissions=20of=2046=20bits=20were=20made,=20each=20= lasting=20=20132
=0D=0Aminutes=20with=20a=2020=20minute=20carrier=20test=20in= =20between. =20ERP=20=20was
=0D=0Aprobably=20around=205=20or=2010=20uW=20= and=20the=20range=20is=201028=20km.
=0D=0A
=0D=0AEb/N0=20was=20=20about=20= -0.5dB=20in=20the=20first=20test=20and=20about=20-1.5=20dB
=0D=0Ain=20the=20s= econd,=20which=20is=20=20below=20-7dB=20in=20the=20symbol=20bandwidth
=0D=0Ao= f=2033.3=20mHz.
=0D=0A
=0D=0ABoth=20messages=20were=20=20decoded=20with=20= some=20margin=20to=20spare.
=0D=0A
=0D=0AThe=20decoder=20is=20a=20list=20V= iterbi=20decoder=20=20using=20the=20tree=20trellis
=0D=0Aalgorithm=20with=20a= =20list=20length=20of=202000=20and=20stack=20size=20=2020000.
=0D=0ABoth=20me= ssages=20decoded=20at=20the=20top=20of=20the=20list=20so=20the=20list
=0D=0Ad= ecoding=20=20wasn't=20actually=20necessary=20for=20this=20strength=20of=20signal= .
=0D=0A
=0D=0AThe=20transmitter=20=20uses=20a=20rubidium=20source=20and=20= the=20receiver=20is
=0D=0AGPS=20timed.  =20A=20reference=20=20phase= =20at=20the=20receiver=20is=20obtained=20by
=0D=0Aaveraging=20the=20phase=20o= f=20the=20squared=20=20signal=20but=20at=20such=20low=20signal
=0D=0Astrength= s=20the=20resulting=20reference=20is=20unreliable=20=20and=20the=20decoder
=0D= =0Amakes=20a=20search=20for=20the=20correct=20phase=20and=20phase=20drift=20=20r= ate.
=0D=0A
=0D=0AThe=20signal=20is=20completely=20invisible=20in=20any=20= spectrogram=20at=20=20the
=0D=0Areceiver.  =20In=20a=20spectrogram=20= running=20at=20the=20symbol=20=20bandwidth
=0D=0Athe=20signal=20is=20too=20fa= r=20below=20noise=20and=20the=20bandwidth=20of=20=20the
=0D=0Atransmission=20= is=20such=20that,=20in=20a=20resolution=20capable=20of=20seeing
=0D=0Athe=20=20= signal=20above=20noise,=20the=20signal=20is=20too=20wide.
=0D=0A
=0D=0AFor= =20example,=20this=20spectrogram=20=20uses=20the=20symbol=20bandwidth,
=0D=0A=
=0D=0A =20http://abelian.org/vlf/tmp/df6nm_140510a.png
=0D=0A
= =0D=0AMaybe=20=20someone=20can=20see=20some=20very=20faint=20line=20at=208270.00= 0=20?
=0D=0A
=0D=0AThe=20first=20test=20ran=20=2007:02=20to=2009:12=20and=20= the=20second
=0D=0Afrom=2009:32=20to=2011:44.  =20The=2020=20minute= =20=20carrier=20in=20between=20is
=0D=0Aalso=20below=20noise=20at=20this=20re= solution.
=0D=0A
=0D=0AFollowing=20=20the=20second=20test,=20an=20hour=20o= f=20carrier=20is=20visible=20in
=0D=0Athe=20278=20uHz=20spectrogram=20=20at=0D=0A
=0D=0A =20http://abelian.org/vlf/fbi= ns.shtml#p=3D1399780800&b=3D110&s=3Dsp
=0D=0A
=0D=0AMore=20=20= information=20on=20the=20FEC=20codes,=20trials,=20and=20search=20for
=0D=0Ago= od=20polynomials=20can=20be=20=20found=20at
=0D=0A
=0D=0A =20http://abelian.org/fec
=0D= =0A
=0D=0AStronger=20codes=20=20with=20constraint=20length=20up=20to=2025=20a= re=20available
=0D=0Aand=20hopefully=20further=20tests=20=20will=20be=20made=20= soon.
=0D=0A--
=0D=0APaul=20Nicholson
=0D=0A--
=0D=0A
=0D=0A=20=20= =0D=0A=20=0D=0A ----------MB_8D1DB86D068B4BB_12B4_A0AD2_webmail-vm015.sysops.aol.com--