----- Original Message -----
Sent: Sunday, January 06, 2013 3:12
PM
Subject: LF: Re: Re: Re: Bandlimited SSB
test on 136 kHz
Thanks very much Marco and Terry for trying, and
to Klaus DJ6LB who sent a nice recording from 20 km. I have stopped
transmitting at 13:50 due to onsetting rain, but may resume an hour later
if the weather lets me.
Terry the slow-voice stuff still needs a litte
more work. I will be happy to share it once it runs a bit more reliably. And
despite my scepticism, I would indeed be interested to team up with
Geri and others to try FreeDV on low bands.
Best 73,
Markus (DF6NM)
----- Original Message -----
Sent: Sunday, January 06, 2013 2:54
PM
Subject: RE: Bandlimited SSB test on 136
kHz
Hi
Markus
I
am always interested in new communications
experiments!
I
listened for your test transmission at 13:30 but, unfortunately, heard
nothing. I’ve used my SDR-IQ to record the spectrum so I can analyse off-line
in more detail later.
Although
I am not yet in a position to Tx on 136 kHz, I will try to monitor your
slow SSB tests if you would like to make the software
available.
I
know you do not fancy using DV but just to mention that I have had some
success (on HF) with FreeDV. This uses a recently developed opensource
CODEC and has an 1100 Hz BW.
73
and GL with the tests.
Terry
GW0EZY
----- Original Message -----
Sent: Sunday, January 06, 2013 2:45
PM
Subject: LF: Re: Re: Bandlimited SSB
test on 136 kHz
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 -----
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
GL
73 Marco, IK1HSS
----- Original Message -----
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.
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
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)
...
