References: <56A2952A.7060208@abelian.org>
To: rsgb_lf_group@blacksheep.org
In-Reply-To: <56A2952A.7060208@abelian.org>
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From: Markus Vester <markusvester@aol.com>
Message-Id: <8D3240D41785ED1-1038-6435BD@webmail-vm010.sysops.aol.com>
Date: Sat, 23 Jan 2016 10:52:54 -0500
Subject: VLF: Software PSK modulation
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For=20yesterday's=20EbNaut=20transmission,=20I=20have=20not=20employed=20the=20u=
sual=20Rubidium=20oscillator=20and=20automatic=20antenna=20variometer=20hardware=
,=20but=20reverted=20to=20the=20software=20modulation=20scheme=20which=20had=20b=
een=20originally=20used=20for=20our=20first=20tests=20in=20April=202014.=20This=20=
is=20an=20extension=20of=20the=20"green=20line"=20anti-glitch=20method,=20with=20=
1pps-sync=20in=20SpecLab=20and=20RF=20feedback=20of=20the=20analog=20output=20to=
=20the=20ADC=20input.=20To=20generate=20PSK=20modulation,=20the=20phase=20prescr=
iption=20for=20the=20software=20PLL=20is=20no=20longer=20fixed=20at=20180=C2=B0=20=
(green=20in=20the=20colour=20spectrogram),=20but=20switched=20between=2090=C2=B0=
=20(red)=20and=20270=C2=B0=20(sky-blue)=20by=20a=20SpecLab=20script=20which=20pe=
riodically=20reads=201=20or=200=20symbols=20from=20a=20text=20file.=0D=0A=C2=A0=0D=
=0AThe=20primary=20advantage=20of=20this=20method=20is=20that=20no=20external=20=
hardware=20modulator=20is=20needed.=20With=20the=20feedback=20picked=20up=20from=
=20the=20antenna,=20it=20also=20intrinsically=20compensates=20for=20wind-induced=
=20resonance=20variations=20and=20can=20do=20without=20an=20automatic=20variomet=
er.=20Thirdly,=20the=20phase=20switching=20occurs=20smoothly=20by=20frequency=20=
variation,=20reducing=20switching=20transients=20and=20far-away=20sidebands.=20T=
he=20main=20disadvantage=20is=20that=20the=20phase=20ramping=20takes=20time=20(a=
bout=201=20to=203=20seconds)=20and=20also=20introduces=20some=20jitter,=20so=20t=
his=20method=20cannot=20be=20used=20effectively=20for=20fast=20signaling=20with=20=
symbols=20shorter=20than=205=20seconds.=C2=A0=C2=A0=20=0D=0A=C2=A0=0D=0AIf=20you=
=20would=20like=20to=20try,=20a=20SpecLab=20configuration=20file=20can=20be=20fo=
und=20at=0D=0Ahttp://df6nm.bplaced.net/VLF/_vlf_tx_pll_psk.USR=0D=0A=C2=A0=0D=0A=
To=20use=20it,=20you=20first=20need=20to=20set=20up=20GPS=201pps=20and=20audio=20=
feedback=20as=20described=20in=20=0D=0Ahttp://df6nm.bplaced.net/VLF/VLF_Transmit=
_phase_correction.txt=0D=0AThis=20can=20be=20done=20either=20with=20a=20stereo=20=
input=20soundcard=20(1pps=20on=20the=20right,=20RF=20feedback=20on=20the=20left=20=
channel),=20or=20mono=20with=20both=20signals=20combined=20through=20resistors=20=
(RF=20feedback=20about=205%=20of=20the=201=20pps=20level).=20Make=20sure=20that=20=
the=201pps=20samplerate=20detector=20is=20locking=20properly=20(i.e.=20mostly=20=
green),=20and=20your=20PC=20time=20is=20close=20to=20the=20nearest=20second.=20=0D=
=0A=C2=A0=0D=0AThen=20you=20need=20to=20encode=20your=20message=20using=20Paul's=
=20ebnaut-tx=20software=0D=0Ahttp://abelian.org/ebnaut/=0D=0Aand=20press=20"Save=
"=20to=20make=20a=20text=20file.=20For=20use=20with=20the=20SpecLab=20script,=20=
you=20then=20need=20to=20insert=20spaces=20as=20separators=20between=20the=200=20=
and=201=20digits,=20e.g.=20converting=20"1001..."=20into=20"=201=200=200=201..."=
=20by=20replacing=200s=20and=201s=20in=20notepad=20(note=20that=20"1=200=200=201=
=20..."=20works=20just=20as=20well=20but=20may=20produce=20a=20surprising=20resu=
lt=20when=20reopening=20the=20file=20-=20search=20for=20"bush=20hid=20the=20fact=
s"=20;-)=20As=20an=20example,=20my=20recent=20transmission=20is=20at=0D=0Ahttp:/=
/df6nm.bplaced.net/VLF/psk_8k19a_73.txt=0D=0AThe=20file=20should=20be=20saved=20=
as=20psk.txt=20and=20placed=20in=20your=20SpecLab=20home=20directory.=20=0D=0A=C2=
=A0=0D=0AThen=20you=20will=20want=20to=20select=0D=0A-=20the=20TX=20frequency=20=
in=20the=20second=20oscillator=20of=20the=20test=20signal=20generator,=0D=0A-=20=
the=20symbol=20duration=20as=20periodic=20actions=20interval=20(eg.=2010=20secon=
ds),=0D=0A-=20the=20start=20time,=20by=20letting=20scheduled=20actions=20open=20=
psk.txt=20a=20couple=20of=20seconds=20before.=20You=20should=20also=20close=20th=
e=20file=20after=20the=20transmission,=20=0D=0A-=20and=20finally=20tick=20"send=20=
unmodulated=20test=20tone=20at=20TX=20frequency"=20in=20the=20digimode=20termina=
l=20to=20let=20the=20signal=20appear=20on=20the=20left=20output.=0D=0A=C2=A0=0D=0A=
A=20couple=20of=20notes=20regarding=20frequency=20selection:=20For=20straight=20=
carrier=20experiments,=20staying=20within=20very=20few=20mHz=20of=208270=20Hz=20=
can=20show=20the=20signal=20on=20various=20grabbers.=20However=20EbNaut=20PSK=20=
reception=20would=20be=20susceptible=20to=20co-channel=20interference=20over=20a=
=20wider=20bandwidth,=20eg.=20+-=200.1=20Hz=20for=2010=20second=20symbols.=20As=20=
the=20PSK=20signal=20will=20anyway=20be=20invisible=20on=20the=20grabbers,=20it=20=
might=20be=20advisable=20to=20choose=20e.g.=208970.1=20or=208969.9=20Hz=20for=20=
future=20PSK=20transmissions,=20thereby=20nulling=20potential=20carriers=20near=20=
8270.000=20but=20still=20staying=20inside=20the=20decimated=20IQ=20bandwidth=20f=
or=20EbNaut=20recordings=20(+-0.25=20Hz=20here).=20=0D=0A=C2=A0=0D=0AAs=20SpecLa=
b=20aligns=20the=20absolute=20phase=20to=20time-of-day,=20the=20TX=20frequency=20=
for=20overnight=20transmissions=20should=20be=20a=20multiple=20of=201/86400=20Hz=
=20to=20avoid=20an=20Alpha-like=20midnight=20phase=20step.=0D=0A=C2=A0=0D=0AHope=
=20this=20may=20help=20to=20get=20a=20few=20more=20EbNaut=20signals=20on=20air..=
.=20Big=20thanks=20to=20Paul=20and=20Wolf=20for=20making=20all=20this=20possible=
.=20=0D=0A=C2=A0=0D=0AAll=20the=20best,=20=0D=0AMarkus=20(DF6NM)=0D=0A=C2=A0=0A=0A=

----------MB_8D3240D41EF63C3_1038_BCEAFD_webmail-vm010.sysops.aol.com
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Content-Type: text/html; charset="utf-8"

=0D=0A<div=20style=3D"color:=20black;=20font-family:=20arial;=20font-size:=2010p=
t;"><font=20color=3D"black"=20face=3D"arial"></font><span=20style=3D"display:=20=
inline-block;"=20contenteditable=3D"false"></span></div>=0D=0A=0D=0A<div>For=20y=
esterday's=20EbNaut=20transmission,=20I=20have=20not=20employed=20the=20usual=20=
Rubidium=20oscillator=20and=20automatic=20antenna=20variometer=20hardware,=20but=
=20reverted=20to=20the=20software=20modulation=20scheme=20which=20had=20been=20o=
riginally=20used=20for=20our=20first=20tests=20in=20April=202014.=20This=20is=20=
an=20extension=20of=20the=20"green=20line"=20anti-glitch=20method,=20with=201pps=
-sync=20in=20SpecLab=20and=20RF=20feedback=20of=20the=20analog=20output=20to=20t=
he=20ADC=20input.=20To=20generate=20PSK=20modulation,=20the=20phase=20prescripti=
on=20for=20the=20software=20PLL=20is=20no=20longer=20fixed=20at=20180=C2=B0=20(g=
reen=20in=20the=20colour=20spectrogram),=20but=20switched=20between=2090=C2=B0=20=
(red)=20and=20270=C2=B0=20(sky-blue)=20by=20a=20SpecLab=20script=20which=20perio=
dically=20reads=201=20or=200=20symbols=20from=20a=20text=20file.</div>=0D=0A=0D=0A=
<div>&nbsp;</div>=0D=0A=0D=0A<div>The=20primary=20advantage=20of=20this=20method=
=20is=20that=20no=20external=20hardware=20modulator=20is=20needed.=20With=20the=20=
feedback=20picked=20up=20from=20the=20antenna,=20it=20also=20intrinsically=20com=
pensates=20for=20wind-induced=20resonance=20variations=20and=20can=20do=20withou=
t=20an=20automatic=20variometer.=20Thirdly,=20the=20phase=20switching=20occurs=20=
smoothly=20by=20frequency=20variation,=20reducing=20switching=20transients=20and=
=20far-away=20sidebands.=20The=20main=20disadvantage=20is=20that=20the=20phase=20=
ramping=20takes=20time=20(about=201=20to=203=20seconds)=20and=20also=20introduce=
s=20some=20jitter,=20so=20this=20method=20cannot=20be=20used=20effectively=20for=
=20fast=20signaling=20with=20symbols=20shorter=20than=205=20seconds.&nbsp;&nbsp;=
=20</div>=0D=0A=0D=0A<div>&nbsp;</div>=0D=0A=0D=0A<div>If=20you=20would=20like=20=
to=20try,=20a=20SpecLab=20configuration=20file=20can=20be=20found=20at<br>=0D=0A=
<a=20href=3D"http://df6nm.bplaced.net/VLF/_vlf_tx_pll_psk.USR">http://df6nm.bpla=
ced.net/VLF/_vlf_tx_pll_psk.USR</a></div>=0D=0A=0D=0A<div>&nbsp;</div>=0D=0A=0D=0A=
<div>To=20use=20it,=20you=20first=20need=20to=20set=20up=20GPS=201pps=20and=20au=
dio=20feedback=20as=20described=20in=20<br>=0D=0A<a=20href=3D"http://df6nm.bplac=
ed.net/VLF/VLF_Transmit_phase_correction.txt">http://df6nm.bplaced.net/VLF/VLF_T=
ransmit_phase_correction.txt</a><br>=0D=0AThis=20can=20be=20done=20either=20with=
=20a=20stereo=20input=20soundcard=20(1pps=20on=20the=20right,=20RF=20feedback=20=
on=20the=20left=20channel),=20or=20mono=20with=20both=20signals=20combined=20thr=
ough=20resistors=20(RF=20feedback=20about=205%=20of=20the=201=20pps=20level).=20=
Make=20sure=20that=20the=201pps=20samplerate=20detector=20is=20locking=20properl=
y=20(i.e.=20mostly=20green),=20and=20your=20PC=20time=20is=20close=20to=20the=20=
nearest=20second.=20</div>=0D=0A=0D=0A<div>&nbsp;</div>=0D=0A=0D=0A<div>Then=20y=
ou=20need=20to=20encode=20your=20message=20using=20Paul's=20ebnaut-tx=20software=
<br>=0D=0A<a=20href=3D"http://abelian.org/ebnaut/">http://abelian.org/ebnaut/</a=
><br>=0D=0Aand=20press=20"Save"=20to=20make=20a=20text=20file.=20For=20use=20wit=
h=20the=20SpecLab=20script,=20you=20then=20need=20to=20insert=20spaces=20as=20se=
parators=20between=20the=200=20and=201=20digits,=20e.g.=20converting=20"1001..."=
=20into=20"=201=200=200=201..."=20by=20replacing=200s=20and=201s=20in=20notepad=20=
(note=20that=20"1=200=200=201=20..."=20works=20just=20as=20well=20but=20may=20pr=
oduce=20a=20surprising=20result=20when=20reopening=20the=20file=20-=20search=20f=
or=20"bush=20hid=20the=20facts"=20;-)=20As=20an=20example,=20my=20recent=20trans=
mission=20is=20at<br>=0D=0A<a=20href=3D"http://df6nm.bplaced.net/VLF/psk_8k19a_7=
3.txt">http://df6nm.bplaced.net/VLF/psk_8k19a_73.txt</a><br>=0D=0AThe=20file=20s=
hould=20be=20saved=20as=20psk.txt=20and=20placed=20in=20your=20SpecLab=20home=20=
directory.=20</div>=0D=0A=0D=0A<div>&nbsp;</div>=0D=0A=0D=0A<div>Then=20you=20wi=
ll=20want=20to=20select<br>=0D=0A-=20the=20TX=20frequency=20in=20the=20second=20=
oscillator=20of=20the=20test=20signal=20generator,<br>=0D=0A-=20the=20symbol=20d=
uration=20as=20periodic=20actions=20interval=20(eg.=2010=20seconds),<br>=0D=0A-=20=
the=20start=20time,=20by=20letting=20scheduled=20actions=20open=20psk.txt=20a=20=
couple=20of=20seconds=20before.=20You=20should=20also=20close=20the=20file=20aft=
er=20the=20transmission,=20<br>=0D=0A-=20and=20finally=20tick=20"send=20unmodula=
ted=20test=20tone=20at=20TX=20frequency"=20in=20the=20digimode=20terminal=20to=20=
let=20the=20signal=20appear=20on=20the=20left=20output.</div>=0D=0A=0D=0A<div>&n=
bsp;</div>=0D=0A=0D=0A<div>A=20couple=20of=20notes=20regarding=20frequency=20sel=
ection:=20For=20straight=20carrier=20experiments,=20staying=20within=20very=20fe=
w=20mHz=20of=208270=20Hz=20can=20show=20the=20signal=20on=20various=20grabbers.=20=
However=20EbNaut=20PSK=20reception=20would=20be=20susceptible=20to=20co-channel=20=
interference=20over=20a=20wider=20bandwidth,=20eg.=20+-=200.1=20Hz=20for=2010=20=
second=20symbols.=20As=20the=20PSK=20signal=20will=20anyway=20be=20invisible=20o=
n=20the=20grabbers,=20it=20might=20be=20advisable=20to=20choose=20e.g.=208970.1=20=
or=208969.9=20Hz=20for=20future=20PSK=20transmissions,=20thereby=20nulling=20pot=
ential=20carriers=20near=208270.000=20but=20still=20staying=20inside=20the=20dec=
imated=20IQ=20bandwidth=20for=20EbNaut=20recordings=20(+-0.25=20Hz=20here).=20</=
div>=0D=0A=0D=0A<div>&nbsp;</div>=0D=0A=0D=0A<div>As=20SpecLab=20aligns=20the=20=
absolute=20phase=20to=20time-of-day,=20the=20TX=20frequency=20for=20overnight=20=
transmissions=20should=20be=20a=20multiple=20of=201/86400=20Hz=20to=20avoid=20an=
=20Alpha-like=20midnight=20phase=20step.</div>=0D=0A=0D=0A<div>&nbsp;</div>=0D=0A=
=0D=0A<div>Hope=20this=20may=20help=20to=20get=20a=20few=20more=20EbNaut=20signa=
ls=20on=20air...=20Big=20thanks=20to=20Paul=20and=20Wolf=20for=20making=20all=20=
this=20possible.=20</div>=0D=0A=0D=0A<div>&nbsp;</div>=0D=0A=0D=0A<div>All=20the=
=20best,=20<br>=0D=0AMarkus=20(DF6NM)</div>=0D=0A=0D=0A<div>&nbsp;</div>=0D=0A
----------MB_8D3240D41EF63C3_1038_BCEAFD_webmail-vm010.sysops.aol.com--