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Swap pictures with slow scan television

Slow Scan TV (SSTV) is a way amateurs send images over the radio. Unlike Fast Scan TV, which has movement, SSTV is a series of still pictures. The advantage though is its narrow bandwidth. This means that SSTV pictures can be sent with an ordinary SSB or FM voice transmitter. With a bandwidth of a few kilohertz (as opposed to megahertz) SSTV tranmissions are narrow enough to occur on the HF radio bands. This readily gives coverage over hundreds or thousands of kilometres, just like SSB voice. As you'll see it's surprisingly effective with low power, especially if images are kept simple with high contrast and a slower transmission mode (selectable on the software) is used.

SSTV predates modern computer based digital modes. However setup and equipment is very similar. You need (i) a computer with sound capabilities (like they all have now), (ii) suitable software (easily downloadble off the web), (iii) an interface cable conveying to and from the transceiver and (iv) an HF SSB-capable transceiver, preferably equipped with VOX (voice operated transmit). Another option, possibly better for portable SSTVers is to use a mobile phone app like DroidSSTV. Again that needs a cable to connect to your transceiver. Because SSTV is 100% duty cycle on transmit your transmitter's output power should be set at around 30 to 50% of that which you'd use on SSB.

SSTV has various frequencies that are popular. 14.230 MHz is most well known. However there is localised SSTV activity on other bands such as 80 and 40 metres. SSTV has a distinctive sound on the air that you will soon recognise. Both analogue and digital SSTV exists, with digital often providing sharper pictures and the ability to send other types of data. Some areas have regular SSTV nets where you'd be most welcome. Enjoy the videos below for various aspects of SSTV activity.

 

DX SSTV from halfway across the world

 

Milliwatt QRP SSTV tests on 14 MHz

 

Some unexpected portable SSTV (in the middle of the day on 80m)

 

Introduction to digital picture transmission (including Easypal) by VK3AML

 

Summary

These videos show some of the variety that is SSTV activity. SSTV pictures can be viewed on online SSTV cams such as these. A simple cable to connect your laptop computer to your transceiver is described here. That cable in conjunction with software and a suitable HF SSB transceiver will get you transmitting and receiving SSTV.

 

 

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