Re: Shortwave Radiogram, 11 Mar 2018


Wa4kfz
 

Just a reminder: you will not be able to directly decode the image when it is centered at 750Hz. For these tests, you need to record the broadcast, double the playback speed, and decode the reconstituted image (which will now appear centered back at 1500Hz).

73,
Mark WA4KFZ

On Mar 11, 2018, at 8:48 PM, Jim Fisher <jedijf@myfisher.org> wrote:

And even with all that noise, antenna collapsed, you got the header to
record the noisey part of the image. It didn't get legible until
midway.....

On 3/11/18, Jim Fisher <jedijf@myfisher.org> wrote:
That SUCKS - would have been an awesome experiment.

On 3/11/18, Bill <wd9eqd@gmail.com> wrote:
I tried an experiment.



I used the S-8800, antenna totally collapsed, set to

LOCAL instead of DX. Signal was very noisy. But I could

copy the text. Following is image at normal speed:







Pretty bad. But I had hopes for the half speed image.

Unfortunately, I had a burst of noise, and did not get the

PIC ID, so no picture at Half Speed. Darn!!



That’s the one down side – if you miss the PIC header,

even if the rest is solid copy, then no copy on the photo.



Now to set the SDRPlay up to record both frequencies

in the morning.







73

Bill

WD9EQD









From: Ron Wenig [mailto:rwenig@verizon.net]
Sent: Sunday, March 11, 2018 8:37 PM
To: nbems@groups.io; main@digitalradio.groups.io
Subject: Shortwave Radiogram, 11 Mar 2018



Hi Kim,

Good experiment with the image sent normal and half speed. The second
show
at 2330 UTC reception, S30 was much better than at 2030 UTC show S5 here
near Philadelphia. Here are the two images. I used audacity to record
the
show and then increased the speed to decode the 2nd image. While
receiving
the second image at 1/2 the speed I noticed the signal was down at 750 Hz
from 1500 Hz on the waterfall. I think this is because the speed of the
transmission was cut in half and that changed the frequency of the audio
1/2.




Image sent normal speed Image sent 1/2 speed

So the image seemed to improve with the reduction in speed. Thanks that
was
fun.

73, Ron NY3J


--
jim fisher
Jedijf
AJ3DI
www.aj3di.com/
www.myfisher.org

"Do, or do not. There is no 'try.'"
-- Jedi Master Yoda

--
jim fisher
Jedijf
AJ3DI
www.aj3di.com/
www.myfisher.org

"Do, or do not. There is no 'try.'"
-- Jedi Master Yoda


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