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LF: Re: Re: Re: Bandlimited SSB test on 136 kHz

To: <[email protected]>
Subject: LF: Re: Re: Re: Bandlimited SSB test on 136 kHz
From: "Markus Vester" <[email protected]>
Date: Sun, 6 Jan 2013 15:12:32 +0100
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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)
...
   
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