SSTV from VK2DAG/P on VK2/CT-012

Matt VK2DAG was travelling up to the Central Tablelands of NSW to try some microwave summit-to-summit contacts with Justin VK2CU on Mt Canobolas VK2/CT-001 from Mt Lambie VK2/CT-007 – or at least that was the plan. On the way he stopped at Mt Banks VK2/CT-032, decided it was too windy (and I expect too far to lug the gear). Continuing on he arrived at the Glowworm Tunnel Rd summit VK2/CT-012 just north of Lithgow. This summit has no obvious peak and is surrounded by tall trees – not a good takeoff for microwaves, but great for HF.

After Matt activated the summit on 40m SSB he was keen to send some SSTV. Moving off 7090 kHz to 7105 kHz for the mode change, Matt took a photo and transferred it to his laptop. He then sent this picture in Robot 36 format:

First SSTV image of VK2/CT-012 in Robot 36 format

First image from VK2/CT-012 in Robot 36 format

The whole image was received without QRM, however it contained quite a few white dots and Matt thought this might be due to overdriving the audio on the transceiver. The resolution was also a little low for such a busy picture so I suggested using Martin 2 instead. In the end, Matt sent the SSTV image again using Martin 1 (which takes even longer than Martin 2). Here is the result:

Second image from VK2/CT-012 in Martin 1 format

Second image from VK2/CT-012 in Martin 1 format

Nice picture, Matt! The image has much higher resolution than the first one. There are still white dots, but they are less obtrusive. The white line near the bottom is due to local QRM (I forgot to disable local HF transmitters). It looks like the summit is recovering nicely from last September’s bushfire. I can clearly see green grass now whereas it was all black when I activated.

With Matt having a computer available, he was also able to receive SSTV. I suggested it would be possible for me to send the picture back. Not having sent an SSTV picture before, there was a bit of hunting around for all the right buttons in MMSSTV to get the received picture transferred to the transmit frame. Then the problem I had was eliminating the template that seemed to automatically pop up over the top. A bit more playing and that was gone and then I was able to send it back in Robot 36 format. I haven’t seen the result, but Matt could identify the white dots that I was talking about.

Maybe this is the first time SSTV has been sent and received on a summit!
To qualify as an SSTV QSO it would require sending signal reports both ways in SSTV. We aren’t far away from this.

Thanks, Matt. Another summit via SSTV to add to the collection.

 

UPDATE 5/8/14: Here is the picture that Matt received on the summit from me:

Image received by Matt on the summit from me

Image received by Matt on the summit from me

Not ideal! Clearly one or both of us has work to do. I’ll be trying out sending locally to make sure things are working. This was sent in Robot 36 format which has lower resolution, but still there seems to be a synchronisation issue. The blue, magenta and yellow bands on the left of the picture seem like mysterious echoes of the sync pulse. It’s all up from here…

Thanks for the pingback, Matt.

SSTV from VK3ASC/P on VK3/VE-105

Sunday afternoon and another summit activation by Mark VK3ASC, this time on Mt Big Ben VK3/VE-105. He came up on 20m SSB and surprised me by being an easy 5×9 copy over the short 473 km path. Half an hour later after scooping up some of the regular SSB SOTA chasers on 40m he popped up on 7180 with a spot announcing SSB/SSTV. I found Mark chatting to Matt VK1MA who was setting up MMSSTV to receive a picture. Pretty soon after that the chirping sounds of SSTV were coming through. I was still getting MMSSTV running on the right sound port and so ended up missing the first 10 seconds of the picture. The software still managed to start itself automatically from the horizontal sync pulses so I did get a picture, albeit without the blue sky at the top. Here it is:

Mt Big Ben - first picture

Mt Big Ben – first picture

Yep, a pretty grainy picture which was no surprise considering Mark was about S2 and dropping into the noise. I did have trouble understanding all that he was saying, a far cry from the armchair contact half an hour before on 20m. There was also a lot of static crashes and it turned out there were 2 storm cells within radio range as you can see on the lightning map:

Active lightning storms within range on 40m

Active lightning storms within range on 40m

Mark sent the picture again and this time it did not start properly, then about 20% of the picture was received and then there was a resync and restart with another 20% being received. None of those were saved, but it was indicative of how poor the conditions were.

Mark sent the picture a third time, and signals seemed to improve. I managed to receive the whole frame this time, though there was still quite a bit of noise. The blue sky was obvious now…

Mt Big Ben - second picture

Mt Big Ben – second picture

A frame was also received by Matt VK1MA, and he reported significant slant to the image. So, not ideal conditions,  but an impression of the summit was received. There has been some discussion on the SOTA reflector about using digital transmission methods for SSTV images. With the very poor signals experienced I don’t think anything would have been received without use of very strong forward error correction – which is not currently available. There is certainly a place for analogue SSTV.

Mark later went up to 20m and announced another SSB/SSTV spot. It was less than an hour since I worked him on that band but by then his signal was nowhere to be seen. As it turned out, 30m would have been the optimal band for the path.

Thanks for another picture, Mark.

SSTV from VK3ASC/P on VK3/VE-208

Mark, VK3ASC activated summit VK3/VE-208 Jarvis Creek Plateau on PSK31 and SSTV Saturday afternoon 31 May 2014. On 30m he sent a picture of the summit a number of times on Slow Scan TV. The first attempt was using Scottie 1 mode which takes nearly 2 minutes for a 240 line picture of 320 pixels. I was using MMSSTV but the software did not recognise the start of the picture so I kicked it off manually and so only received the bottom part of the picture.

Image

Mark is using Wolphi’s DroidSSTV software on his Android smartphone. I suggested he switch to Scottie 2 which reduces the transmission time to just over a minute. At the same time, I was fiddling with the audio input level on my soundcard as the level was saturating. This could cause the failure to recognise the start of the picture due to audio distortion even though SSTV is really an FM mode so amplitude variations should play no part. This is what was received in Scottie 2 mode:

Image

The start of the picture was being recognised and the whole frame was received. There was quite a lot of sparkly noise in the frame so Mark suggested sending again. I further reduced the input level in case the audio was still saturating. There were quite a few static crashes but it seemed as though the picture could be improved. The final picture received was this:

Image

There was a lot less noise this time and it was much more recognisable. Mark attempted to raise the contrast in this picture by adjustments in the DroidSSTV app but it seemed to have no obvious effect. Certainly, a great first attempt at sending and receiving an SSTV image from a summit. Also check out Matt VK2DAG’s blog as he received the images too.

Thanks to Mark, VK3ASC!