SSTV: Difference between revisions
(→Linux) |
No edit summary |
||
| (6 intermediate revisions by 2 users not shown) | |||
| Line 1: | Line 1: | ||
'''Slow-scan television (SSTV)''' | '''Slow-scan television (SSTV)''' allows you to send photos and other images over amateur radio. A phone or computer converts the picture into sound waves, which are sent over a radio. When another operator's radio receives these signals and their phone or computer decodes them, the image appears on the recipient's screen. | ||
A more general term for technologies including SSTV is narrowband television (NBTV). Analog broadcast television requires at least 6 | 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.) | ||
Because SSTV signals are comparable in [[Glossary#bandwidth|bandwidth]] to voice signals, 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]]. | 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]]. | ||
| Line 31: | Line 31: | ||
=== iOS and iPadOS === | === iOS and iPadOS === | ||
An [https://apps.apple.com/us/app/sstv/id387910013 SSTV decoder/encoder app] is available for the iPhone and iPad, but | An [https://apps.apple.com/us/app/sstv/id387910013 SSTV decoder/encoder app] is available for the iPhone and iPad, but it is a paid app (it currently costs $2.99), and no PBARC members currently use it, so it may be difficult to find help and it is not known how well it works. | ||
=== Windows === | === Windows === | ||
| Line 39: | Line 39: | ||
=== Linux === | === 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 | 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 distribution's software manager. | ||
So far, all PBARC members who have tried to use QSSTV have had various problems with it that made it unusable. | So far, all PBARC members who have tried to use QSSTV have had various problems with it that made it unusable. | ||
=== MacOS === | === MacOS === | ||
[https://qsl.net/v/ve3elb/KD6CJI-MultiScan3B/ MultiScan3B] by KD6CJI is available as a free download. The European Space Agency has a [https://www.esa.int/ESA_Multimedia/Videos/2020/07/Mac_OSX_tutorial_How_to_receive_SSTV_pictures_from_the_International_Space_Station video tutorial] installation and use. | |||
[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. | [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. | ||
| Line 116: | Line 118: | ||
290 seconds (4 minutes 50 seconds) per picture | 290 seconds (4 minutes 50 seconds) per picture | ||
<hr> | |||
[ | |||
[ | {{Wikipedia|Slow-scan television}} | ||
<p>This page contains content copied from or based on the OpenHam.Wiki article "[https://openham.wiki/index.php/Slow-scan_television Slow-scan television]." Copyright © OpenHam.Wiki contributors. Used under [https://creativecommons.org/licenses/by-sa/4.0/ CC BY-SA 4.0 International].<p> | |||
Latest revision as of 12:08, 5 December 2023
Slow-scan television (SSTV) allows you to send photos and other images over amateur radio. A phone or computer converts the picture into sound waves, which are sent over a radio. When another operator's radio receives these signals and their phone or computer decodes them, the image appears on the recipient's screen.
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.)
Because SSTV signals are comparable in bandwidth to voice signals, 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 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.
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 SSTV decoder/encoder app is available for the iPhone and iPad, but it is a paid app (it currently costs $2.99), and no PBARC members currently use it, so it may be difficult to find help and it is not known how well it works.
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 distribution's software manager.
So far, all PBARC members who have tried to use QSSTV have had various problems with it that made it unusable.
MacOS
MultiScan3B by KD6CJI is available as a free download. The European Space Agency has a video tutorial installation and use.
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
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
This page contains content copied from or based on the Wikipedia article "Slow-scan television." Copyright © Wikipedia contributors. Used under CC BY-SA 3.0 Unported.
This page contains content copied from or based on the OpenHam.Wiki article "Slow-scan television." Copyright © OpenHam.Wiki contributors. Used under CC BY-SA 4.0 International.
