View source for 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&nbsp;MHz wide channels, because it transmits 25 or 30 picture frames per second, but SSTV usually only takes up to a maximum of 3&nbsp;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]].

For best image quality, a radio-computer interface such as a [[SignaLink]] can be used. However, the "air link" method of holding the radio's microphone near the computer's speaker and vice versa can also be used, at the expense of image quality.

== Software ==

=== Android ===

On Android, the transmit and receive functions are provided by separate apps. The encoder, simply called "SSTV Encoder," is available on the [https://play.google.com/store/apps/details?id=om.sstvencoder Google Play Store] and on [https://f-droid.org/packages/om.sstvencoder 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 [https://play.google.com/store/apps/details?id=xdsopl.robot36 Play Store] and from [https://f-droid.org/packages/xdsopl.robot36 F-Droid].

Air link works fine with Android devices, and it is much more convenient than with a laptop or (especially) a desktop. However, with a "USB On-The-Go" adapter, many phones and tablets will work with the SignaLink.

==== Sending pictures ====

To send a picture, use the "SSTV Encoder" app.

First, tap the three-dot menu, then tap "Modes" and select a mode. PD90 is a good compromise between image quality and transmission time; it takes 90 seconds.

Tap the photo frame button and select an image. (The camera button should allow pictures to be taken from within the app, but this feature is buggy. It is better to take a picture with the normal camera app first.) Zoom and drag the picture as desired; the part within the frame will be transmitted.

Tap anywhere within the frame to add text at that location; an editor will open in which you can enter text and change the font size, style, and color. Click the check mark when you are done. If you want to edit text that is already on the image; tap the text, and the editor will open with that text pre-loaded. When you click the checkmark, it will save the edit. To remove text, simply edit it and remove all of the text; you can use the X icon to do this.

To send the image, turn your media volume up and tap the "play" icon.

=== iOS and iPadOS ===

An [https://apps.apple.com/us/app/sstv/id387910013 SSTV decoder/encoder app] is available for the iPhone and iPad, but please note that it is a paid app (it currently costs $2.99), and that no PBARC members currently use it, so it may be difficult to find help and it is not known how well it works.

=== Windows ===

[https://hamsoft.ca/pages/mmsstv.php 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 [https://github.com/ON4QZ/QSSTV the GitHub repository]. Otherwise, search for "QSSTV' in your distributions software manager.

So far, all PBARC members who have tried to use QSSTV have had various problems with it that made it unusable.

=== MacOS ===

[https://www.blackcatsystems.com/software/multimode.html MultiMode Cocoa] apparently supports several SSTV modes along with some digital modes such as [[PSK31]], but it costs $89 and is not used by any PBARC members, putting it in a similar situation as the iOS app.

== Samples ==

=== Robot ===
 
==== Robot 36 ====
[[File:SSTV Robot36 Leo.wav]]

36 seconds per picture

==== Robot 72 ====
[[File:SSTV Robot72 Leo.wav]]

72 seconds (1 minute 12 seconds) per picture

=== Scottie ===

==== Scottie 1 ====
[[File:SSTV Scottie1 Leo.wav]]

==== Scottie 2 ====
[[File:SSTV Scottie2 Leo.wav]]

==== Scottie DX ====
[[File:SSTV ScottieDX Leo.wav]]

=== Martin ===
 
==== Martin 1 ====
[[File:SSTV Martin1 Leo.wav|Martin 1]]

==== Martin 2 ====
[[File:SSTV Martin2 Leo.wav|Martin 2]]

=== PD ===

==== PD 50 ====
[[File:SSTV PD50 Leo.wav]]

50 seconds per picture

==== PD 90 ====
[[File:SSTV PD90 Leo.wav]]

90 seconds (1 minute 30 seconds) per picture

==== PD 120 ====
[[File:SSTV PD120 Leo.wav]]

120 seconds (2 minutes) per picture

==== PD 160 ====
[[File:SSTV PD160 Leo.wav]]

160 seconds (2 minutes 40 seconds) per picture

==== PD 180 ====
[[File:SSTV PD180 Leo.wav]]

180 seconds (3 minutes) per picture

==== PD 240 ====
[[File:SSTV PD240 Leo.wav]]

240 seconds (4 minutes) per picture

==== PD 290 ====
[[File:SSTV PD290 Leo.wav]]

290 seconds (4 minutes 50 seconds) per picture

{{CC BY-SA}}{{Wikipedia|Slow-scan television}}