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From: "Marco Cadeddu" <marcocadeddu@tin.it>
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Date: Sun, 6 Jan 2013 13:45:06 -0000
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Content preview: Sorry Markus... I see from your grabber that you started..
but nothing here to hear..just a steady tone on 137.5 will qsy back on 472
wspr (rx only!) 73 de Marco, IK1HSS ----- Original Message ----- From: Marco
Cadeddu To: Sunday, January 06, 2013 1:06 PM Subject: LF: Re: Bandlimited
SSB test on 136 kHz [...]
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Subject: LF: Re: Re: Bandlimited SSB test on 136 kHz
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Sorry Markus...
I see from your grabber that you started.. but nothing here to =
hear..just a steady tone on 137.5
will qsy back on 472 wspr (rx only!)
73 de Marco, IK1HSS
----- Original Message -----=20
From: Marco Cadeddu=20
To: rsgb_lf_group@blacksheep.org=20
Sent: Sunday, January 06, 2013 1:06 PM
Subject: LF: Re: Bandlimited SSB test on 136 kHz
Hi Markus,
stucked of bad cnd on 472 (Stefan arrives irregularly with -30 dB =
S/N....) I'm now in rx usb on 136=20
GL
73 Marco, IK1HSS
----- Original Message -----=20
From: Markus Vester=20
To: rsgb_lf_group@blacksheep.org=20
Sent: Sunday, January 06, 2013 12:50 PM
Subject: LF: Bandlimited SSB test on 136 kHz
Dear LF,
around midday I have been conducting some test transmissions using =
136.0 kHz USB voice. To comply with German regulations, the audio =
spectrum has been cut off sharply below 300 Hz and above 1100 kHz, =
occupying 136.3 to 137.1 kHz RF. Despite this rather mediocre speech =
quality, it is still possible to hear the voice and copy a simple =
message.=20
To my surprise, the speech was quite audible on the Twente WebSDR =
(434 km), squeezed between the bursts of DCF and HGA. There's a =
recording and screenshot at
http://www.df6nm.bplaced.net/LF/ssb/
Of course it does get boring speaking only to myself ;-). If you'd =
like to listen yourself, I intend to do another test transmission =
starting 13:30 this afternoon. As the audio is realtime and standard SSB =
(apart from the filtering), no software postprocessing is needed..
Slow voice transmission (ie the audio deceleration/acceleration =
method originally used by DK8KW and myself) would be nicer as it can fit =
a full SSB channel into 800 Hz. I have been working on a semi-automatic =
control, with a fixed one minute raster similar to JT9-1. This will =
hopefully allow us to comfortably exchange one 20 second voice message =
per time slot (speak during seconds 0 to 20, concurrent transmit and =
receive at 1/3 speed from 0 to 60, replay starting 40 to 60). Anyone =
interested?
Best 73,
Markus (DF6NM)
=20
----- Original Message -----=20
From: Markus Vester=20
To: rsgb_lf_group@blacksheep.org=20
Sent: Thursday, January 03, 2013 12:33 PM
Subject: Re: LF: SSB - why not go digital?=20
Hi Geri, all,
I like the idea of trying voice on MF or even LF, and I was =
fascinated by actually hearing Gus talking on 507 kHz, and Geri on LF =
slow voice. I admit that I even tried (low-power daytime) SSB above =
135.7 kHz once, and Stefan was actually able to hear and record my =
voice, albeit at marginal SNR at 180 km. As my LF TX antenna is fairly =
narrowband (Q ~ 200), I had inserted a phase shifter to transform the =
low output impedance of the PA into a current source at the feedpoint.
The good thing about slow voice is that we also get the SNR gain =
associated with the narrower bandwidth. But the non-realtime operating =
procedure is sort of difficult. We did use "roger beeps" to mark the end =
of message, but there is always an inconvenient delay for recording and =
replaying the messages. So some sort of realtime narrowband voice =
transmission would indeed be desirable.
However I would NOT fancy digital voice modes at all. For one, =
like all digital modes it's all-or-nothing. Either the message decodes =
well, or you get garbage, and you don't know what has been going on in =
the channel. In linear analog SSB, you hear if someone else is calling =
on frequency, or what type of interference came up, or whether there is =
selective fading. The other thing I don't like about digital modes is =
that they tend to occupy the whole channel permanently with high average =
power - just look at the spectra of DRM vs AM modulated BC =
transmissions. It may well turn out that a 2 kHz linear SSB transmission =
is much more friendly than a 1 kHz digital channel.=20
I have been making some attempts on analog quasi-realtime =
narrowband voice transmissions. The principle was is much the same that =
has long been used for changing audio speed without changing pitch, ie =
cut the audio into ~ 20 ms grains. To accellerate or reduce bandwidth, =
you either leave out or average several grains, using a sliding window. =
On replay, each grain is repeated to extend it in time. This is not =
difficult to implement. In my own trials, I could maintain speech =
readability with a factor four bandwidth reduction, but it did sound =
very "robotic" because the fixed timing for the grains impressed itself =
onto the voice pitch. I think that there are better ways of adapting the =
timing by tracking the fundamental frequency to preserve the pitch =
modulation. Using Windows media player for accelerating and decelerating =
seemed to provide quite natural speech quality at a reduction factor of =
four.
Regarding the frequency allocations, like Graham I would think =
that on MF the narrowband beacons should best be placed in narrow slots =
near the band edges. To avoid blocking, we would preferably again use =
split band for west-east vs east-west intercontinental work, as we do on =
LF. Parts of these slots should also be utilized for the slow versions =
of Opera or WSPR. The wider modes would better be placed in the in the =
middle, perhaps with 2 kHz each for CW, middle-range digital modes, and =
one full-width SSB channel.
Best 73,
Markus (DF6NM)
...
------=_NextPart_000_005D_01CDEC14.099EDE40
Content-Type: text/html;
charset="utf-8"
Content-Transfer-Encoding: quoted-printable
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<META http-equiv=3DContent-Type content=3D"text/html; charset=3Dutf-8">
<META content=3D"MSHTML 6.00.2800.1106" name=3DGENERATOR>
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</HEAD>
<BODY bgColor=3D#ffffff>
<DIV><FONT face=3DArial size=3D2>Sorry Markus...</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>I see from your grabber that you =
started.. but=20
nothing here to hear..just a steady tone on 137.5</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>will qsy back on 472 wspr (rx =
only!)</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>73 de Marco, IK1HSS</FONT></DIV>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV=20
style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
<A title=3Dmarcocadeddu@tin.it =
href=3D"mailto:marcocadeddu@tin.it">Marco=20
Cadeddu</A> </DIV>
<DIV style=3D"FONT: 10pt arial"><B>To:</B> <A =
title=3Drsgb_lf_group@blacksheep.org=20
=
href=3D"mailto:rsgb_lf_group@blacksheep.org">rsgb_lf_group@blacksheep.org=
</A>=20
</DIV>
<DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Sunday, January 06, 2013 =
1:06=20
PM</DIV>
<DIV style=3D"FONT: 10pt arial"><B>Subject:</B> LF: Re: Bandlimited =
SSB test on=20
136 kHz</DIV>
<DIV><BR></DIV>
<DIV><FONT face=3DArial size=3D2>Hi Markus,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>stucked of bad cnd on 472 (Stefan =
arrives=20
irregularly with -30 dB S/N....) I'm now in rx usb on 136 =
</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>GL</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>73 Marco, IK1HSS</FONT></DIV>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV=20
style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
<A title=3Dmarkusvester@aol.com =
href=3D"mailto:markusvester@aol.com">Markus=20
Vester</A> </DIV>
<DIV style=3D"FONT: 10pt arial"><B>To:</B> <A=20
title=3Drsgb_lf_group@blacksheep.org=20
=
href=3D"mailto:rsgb_lf_group@blacksheep.org">rsgb_lf_group@blacksheep.org=
</A>=20
</DIV>
<DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Sunday, January 06, =
2013 12:50=20
PM</DIV>
<DIV style=3D"FONT: 10pt arial"><B>Subject:</B> LF: Bandlimited SSB =
test on=20
136 kHz</DIV>
<DIV><BR></DIV>
<DIV><FONT face=3DArial size=3D2>Dear LF,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>around midday I have=20
been conducting some test transmissions using 136.0 =
kHz USB=20
voice. To comply with German regulations, the audio =
spectrum has=20
been cut off sharply below 300 Hz and above 1100 kHz, =
occupying=20
136.3 to 137.1 kHz RF. Despite this rather mediocre speech =
quality, it is still possible to hear the voice and copy a =
simple=20
message. </FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>To my surprise, the speech was =
quite=20
audible on the Twente WebSDR (434 km), squeezed between =
the bursts=20
of DCF and HGA. There's a recording and screenshot at</FONT></DIV>
<DIV><FONT face=3DArial size=3D2><A=20
=
href=3D"http://www.df6nm.bplaced.net/LF/ssb/">http://www.df6nm.bplaced.ne=
t/LF/ssb/</A></FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Of course it does get boring =
speaking only to=20
myself ;-). If you'd like to listen yourself, I intend to do another =
test=20
transmission starting 13:30 this afternoon. As the audio is =
realtime=20
and standard SSB (apart from the filtering), no software =
postprocessing is=20
needed..</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Slow voice transmission (ie =
the audio=20
deceleration/acceleration method originally used by DK8KW and =
myself) would=20
be nicer as it can fit a full SSB channel into 800=20
Hz. I have been working on a semi-automatic control,=20
with a fixed one minute raster similar to JT9-1. This will =
hopefully=20
allow us to comfortably exchange one 20 second voice message per =
time slot=20
(speak during seconds 0 to 20, concurrent=20
transmit and receive at 1/3 speed from 0 to 60,=20
replay starting 40 to 60). Anyone interested?</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Best 73,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Markus (DF6NM)</FONT></DIV>
<DIV><FONT face=3DArial size=3D2> </FONT></DIV>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style=3D"FONT: 10pt arial">----- Original Message ----- =
</DIV>
<DIV=20
style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
<A title=3Dmarkusvester@aol.com =
href=3D"mailto:markusvester@aol.com">Markus=20
Vester</A> </DIV>
<DIV style=3D"FONT: 10pt arial"><B>To:</B> <A=20
title=3Drsgb_lf_group@blacksheep.org=20
=
href=3D"mailto:rsgb_lf_group@blacksheep.org">rsgb_lf_group@blacksheep.org=
</A>=20
</DIV>
<DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Thursday, January 03, =
2013=20
12:33 PM</DIV>
<DIV style=3D"FONT: 10pt arial"><B>Subject:</B> Re: LF: SSB - why =
not go=20
digital? </DIV>
<DIV><FONT face=3DArial size=3D2></FONT><FONT face=3DArial=20
size=3D2></FONT><BR></DIV>
<DIV style=3D"FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: =
arial"><FONT=20
face=3Darial color=3Dblack>Hi Geri, all,</FONT></DIV>
<DIV=20
style=3D"FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: arial"> </DIV>
<DIV style=3D"FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: arial">I =
like the=20
idea of trying voice on MF or even LF, and I was fascinated =
by=20
actually hearing Gus talking on 507 kHz, and Geri on LF slow=20
voice. I admit that I even tried (low-power daytime)=20
SSB above 135.7 kHz once, and Stefan was actually able to =
hear and=20
record my voice, albeit at marginal SNR at 180 km. As my LF TX =
antenna is=20
fairly narrowband (Q ~ 200), I had inserted a phase shifter =
to=20
transform the low output impedance of the PA into a current source =
at the=20
feedpoint.</DIV>
<DIV=20
style=3D"FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: arial"> </DIV>
<DIV style=3D"FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: =
arial">The good=20
thing about slow voice is that we also get the SNR gain associated =
with=20
the narrower bandwidth. But the non-realtime operating procedure=20
is sort of difficult. We did use "roger beeps" to =
mark the=20
end of message, but there is always an=20
inconvenient delay for recording and replaying the=20
messages. So some sort of realtime narrowband voice=20
transmission would indeed be desirable.</DIV>
<DIV=20
style=3D"FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: arial"> </DIV>
<DIV style=3D"FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: =
arial">However I=20
would NOT fancy digital voice modes at all. For one, like all =
digital=20
modes it's all-or-nothing. Either the =
message decodes=20
well, or you get garbage, and you don't know what has been =
going on=20
in the channel. In linear analog SSB, you hear if someone =
else is=20
calling on frequency, or what type of interference came =
up, or=20
whether there is selective fading. The other thing I don't =
like about=20
digital modes is that they tend to occupy the whole channel =
permanently=20
with high average power - just look at the spectra of DRM vs =
AM=20
modulated BC transmissions. It may well turn out that a 2=20
kHz linear SSB transmission is much more friendly than a 1 =
kHz=20
digital channel. </DIV>
<DIV=20
style=3D"FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: arial"> </DIV>
<DIV style=3D"FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: arial">I =
have been=20
making some attempts on analog quasi-realtime narrowband voice=20
transmissions. The principle was is much the same that has long =
been used=20
for changing audio speed without changing pitch, ie cut =
the=20
audio into ~ 20 ms grains. To accellerate or reduce=20
bandwidth, you either leave out or average =
several grains,=20
using a sliding window. On replay, each grain is =
repeated to=20
extend it in time. This is not difficult to implement. In my own =
trials, I=20
could maintain speech readability with a factor four bandwidth =
reduction,=20
but it did sound very "robotic" because the fixed timing =
for the=20
grains impressed itself onto the voice pitch. I think that there =
are=20
better ways of adapting the timing by tracking the =
fundamental=20
frequency to preserve the pitch modulation. Using =
Windows media=20
player<SPAN contentEditable=3Dfalse=20
style=3D"DISPLAY: inline-block"></SPAN> for accelerating and=20
decelerating seemed to provide quite natural =
speech quality=20
at a reduction factor of four.</DIV>
<DIV=20
style=3D"FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: arial"> </DIV>
<DIV style=3D"FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: =
arial">Regarding=20
the frequency allocations, like Graham I would think that on MF =
the=20
narrowband beacons should best be placed in narrow slots near the =
band=20
edges. To avoid blocking, we would preferably again use split =
band=20
for west-east vs east-west intercontinental work, as we do on LF. =
Parts of=20
these slots should also be utilized for the slow versions of Opera =
or=20
WSPR. The wider modes would better be placed in the in the =
middle,=20
perhaps with 2 kHz each for CW, middle-range =
digital=20
modes, and one full-width SSB channel.</DIV>
<DIV=20
style=3D"FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: arial"> </DIV>
<DIV style=3D"FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: =
arial">Best=20
73,</DIV>
<DIV style=3D"FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: =
arial">Markus=20
(DF6NM)<BR> <FONT face=3DArial=20
=
size=3D2>...</FONT></DIV></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BODY></=
HTML>
------=_NextPart_000_005D_01CDEC14.099EDE40--