Tuesday, April 19, 2022

UNDR Group Experiments with KG-STV


There is a great reason for sharing an image like that and no, those black boxes are not censorship but bad pixels when receiving a KG-STV image over amateur radio.

Why send images?

The Ulster and Northern Dutchess Readiness Group is a new organization founded in 2021 to promote ways for the casual radio amateur to learn about preparedness.  

ARES and RACES programs are excellent, but not everyone has the time to dedicate to those or the missions that sometimes prevent a higher level  of local community awareness regarding amateur radio.

Sharing photos for reasons such as training for public works damage assessment or other "grid down" information sharing reasons is an important skill to learn as part of the amateur radio hobby.

Sending photos over a repeater

To help differentiate UNDR Group, the leadership team led by Steve K2GOG has focused on practicing the use of slow scan television (SSTV) images which can be relayed through analog repeaters in the Hudson Valley.

Since October 2021, the UNDR group has found that the PD90 mode is a good trade off between resolution and time needed to send an image with excellent clarity.  A 320 x 240 pixel image sing PD90 takes about 90 seconds from start to finish.

In April 2022, the UNDR Group did an experiment simulating the need to send, receive and re-broadcast an image pretending there was a UFO sighting over the Hudson Valley.

Poughkeepsie UFO,  Highland UFO, Pine Bush UFO
Captured and then rebroadcast SSTV
PD90 image of a pretend UFO over the Hudson Valley
(Courtesy: K2GOG, W2NDG and KD2SQO)

Evolving to digital SSTV

Now that enough members of the UNDR Group have perfected the ability to send and receive images from home or the field using analog SSTV, they have just moved over to learning how to send digital versions of imagery using the KG-STV application.

With normal analog SSTV, one line of the image is sent at a time, scanning from left to right.  As the images is transmitted, those receiving it slowly start to see the image come into view. There are many modes of analog SSTV such as ROBOT36, PD90, SCOTTIE and others. 

KG-STV is different since it is sent digitally in a group of pixels at a time. The sender can choose to send these blocks of pixels in vertical or horizontal rows plus in a randomized sequence.

Sending in a randomized sequence is interesting since it prevents some types of interference or missing large pieces of an image.

Here are two examples of decoding the MARS logo which Steve K2GOG sent as part of an awareness exercise of the Military Auxiliary Radio System.  

This volunteer group managed by U.S Department of Defense via the Army and Air Force has taken a renews interest in collaborating with amateur radio operators for joint readiness exercises.


The image above decoded by Tom N2FZC shows only slight pixilation and the image below from Lou KD2TVS shows a bit more given he is much further away from the repeater compared to Tom which relayed the signal 

For a first time test of KG-STV, this was still a great start as it took on average of 6 times using analog for UNDR Group members to get near perfect copy. 

The reason to experiment with KG-STV is that the application can also send text communications which makes it a valuable tool for when audio communications may not be appropriate. 

When does UNDR Group meet?

Every Monday evening at 8:00 PM Eastern Time is the UNDR Net via the WA2MJM 146.805 analog repeater.  The UNDR Net typically shared a list of announcements including upcoming events at the start and the follows a short thematic discussion. 

At around 8:30 PM, the focus shifts to a form of digital communications which can be shared via the analog repeater.  Different forms of SSTV are the current focus, so please check it out as no other organizations are doing anything else like this in the Hudson Valley and possibly in a larger part of the New York Metro area.

More information about UNDR Group can be found at www.undr-group.com 

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