SSTV
Slow-scan television (SSTV) refers to any method of sending still pictures over amateur radio. Although the vast majority of SSTV activity today uses computers for modulation and demodulation (similar to many digital modes), most SSTV modes are technically analog.
A more general term for technologies including SSTV is narrowband television (NBTV). Analog broadcast television requires at least 6 MHz wide channels, because it transmits 25 or 30 picture frames per second, but SSTV usually only takes up to a maximum of 3 kHz of bandwidth. It is a much slower method of transmission than broadcast television, usually taking from about eight seconds to a couple of minutes, depending on the mode used, to transmit one image frame. Because of this, it is used for still images, not video. (Other NBTV systems, which are less commonly used, transmit video, but at very low resolution.)
Since SSTV systems operate on voice frequencies, they can be used with most amateur transceivers, including on HF, VHF and UHF.
Most SSTV operators today use a personal computer and special software in place of much of the custom equipment formerly necessary. The sound card of a PC, with special processing software, acts as a modem. The computer screen provides the output. A digital camera or saved digital photos provide the input. More recently, it is possible to use an Android smartphone or tablet for SSTV. This can be very convenient, because the camera is integrated into the device and can be easily moved and pointed. This could be especially useful for emergency communications; it is possible to send an image over several miles in only two or three minutes using nothing more than a smartphone and an HT.
Software
Android
On Android, the transmit and receive functions are provided by separate apps. The encoder, simply called "SSTV Encoder," is available on the Google Play Store and on F-Droid. (If you're not sure which link to use, use the Play Store.) The decoder is called "Robot36"; despite the name, it supports many different modes. It is also available from the Play Store and from F-Droid.
Windows
MMSSTV is an SSTV modem for Windows. It has not been updated since 2010, but it still works fine.
Linux
QSSTV is an SSTV program for Linux. If you are familiar with the process for compiling and installing programs from source code, follow the instructions on the GitHub repository. Otherwise, search for "QSSTV' in your distributions software manager.
Samples
Robot
Robot 36
36 seconds per picture
Robot 72
72 seconds (1 minute 12 seconds) per picture
Scottie
Scottie 1
Scottie 2
Scottie DX
Martin
Martin 1
Martin 2
PD
PD 50
50 seconds per picture
PD 90
90 seconds (1 minute 30 seconds) per picture
PD 120
120 seconds (2 minutes) per picture
PD 160
160 seconds (2 minutes 40 seconds) per picture
PD 180
180 seconds (3 minutes) per picture
PD 240
240 seconds (4 minutes) per picture
PD 290
290 seconds (4 minutes 50 seconds) per picture Template:WikipediaCopyright
