Images via Radio!

Image from the International Space Station

Jeffrey Kopcak - K8JTK
Ohio Section Technical Coordinator

Technical Coordinator

The ARRL Technical Coordinator (TC) is a section-level official appointed by the Section Manager to coordinate all technical activities within the section.

  • Supervise and coordinate the work of the section's Technical Specialists (TS).
  • Refer amateurs in the section who need technical advice to local TS.
  • Encourage amateurs in the section to share their technical achievements with others through the pages of QST, at club meetings, hamfests, and conventions.

Technical Coordinator

  • Be available to assist local technical program committees in arranging suitable programs for local club meetings, ARRL hamfests, and conventions.
  • Promote technical advances and experimentation at VHF/UHF and with specialized modes, and work closely with enthusiasts in these fields within the section.

Technical Specialist

For a section team to be effective in one of the most important arenas in Amateur Radio, technology, there must be a cadre of qualified, competent Technical Specialists (TS).

"Advancement of the radio art" is a profound obligation we incur under the rules of the FCC.

TSes help meet this obligation.

Technical Specialist

TS supports the TC in two main areas of responsibility:
Radio Frequency Interference and Technical Information.

Technical Specialist can specialize in certain specific technical areas, or can be generalists.


  • About SSTV & History
  • SSTV Modes
  • Image Comparison
  • Signal Analysis
  • Software & Modern Interfaces
  • Slant
  • QSO & Frequencies
  • Finding out more
  • MMSSTV Tutorial
  • LIVE Demo!!!


...stands for Slow-Scan TV.

Transmission and reception of static images
via radio,
in color or black and white.


  • Line-by-line progression scanning and transmitting of a single image.
  • Downloading images in the dial-up days of the Internet.
  • Utilizes 3 KHz bandwidth.
  • Transmission length varies depending on mode.
  • Considered a digital mode, operated in voice portion of many bands.
  • 100% duty cycle on SSB.

In Contrast to...


  • Fast-scan TV aka HamTV, ATV.
  • 25-30 frames per second.
  • Utilizes 6 MHz wide channels.
  • Broadcast TV.

Digital SSTV

  • DRM - Digital Radio Mondiale.
  • File transfer protocol.
  • Error correction.

Though similar names, completely different.


    Copthorne Macdonald
  • SSTV developed by Copthorne Macdonald (now VY2CM) in 1957.
  • In University of Kentucky Engineering Library, came across Bell System Technical Journal about image transmissions using ordinary phone lines.
  • Could this be adopted to ham radio?
  • Feasibility study to EE Department head, independent study.
  • Ordered surplus CRTs and power transformers from surplus houses like Fair Radio Sales in Lima, Ohio.

img: ARRL


  • Used an electrostatic monitor and vidicon tube.
  • Vidicon Tube
  • Vidicon tube: video camera tube (CRT type).
  • Target material is a photoconductor.
  • Popular 1970 - 1980.
  • Obsolete by CCD and CMOS sensors.
  • Early SSTV images... 120 lines, 120 pixels per line.
  • Black-and-white.
  • 3 kHz of bandwidth.

source & img: Wikipedia

Space Exploration

  • SSTV used alot in early space exploration.
  • No effective way transmit images to ground stations from spacecrafts.
  • Luna 3 was launched in 1959.
  • The first image returned by Luna 3 showed the far side of the Moon was very different from the near side, most noticeably in its lack of lunar maria (the dark areas).
  • Third space probe sent toward moon.
  • First ever photographs from far side of the moon.
  • Poor quality images, never-before-seen views of the far side.

source & img: Wikipedia

Space Exploration

    Strelka on tour, in preserved form, in Australia in 1993.
    Strelka Exibit
  • Vostok 1/Sputnik 5: space dogs Belka and Strelka (10 frames/sec, 100 lines).
  • Vostok 2: 400 line resolution.
  • Krechet: 2nd generation added overlay data.
  • Faith 7 (Mercury-Atlas 9):
    1 frame every 2 seconds.
  • Apollo 7, 8, 9, and 11: 10 frames/sec, 320 lines - TV.
  • More like broadcast TV systems.

source & img: Wikipedia

History: '70s

  • FCC legalized SSTV for amateur use with an Advanced class license in 1969.
  • Required alot of equipment:
    • Scanner or camera image capture.
    • Modem generate/demodulate screeching noise.
    • Transmitter/receiver.
    • Surplus radar gear displayed image.
  • CRT radars had "long persistence" phosphors - image visible for about 10 seconds.

History: 70s - '80s

Modern Systems: '90s - Today

  • PC's replaced customized equipment.
  • (Image) Scanner, digital cameras, or images from the Internet replaced camera.
  • Soundcard with software acts as the modem.
  • Computer screen provides the output.


  • B/W, Robot, AVT, Scottie, Martin, SC (Wrasse), PD, P (Pasokon), MP, MR, ML, MP (narrow), MC (narrow).
  • Different resolutions.
  • Common: 320x256 - 4:3 aspect ratio.
  • Different transmission times.
  • Longer transmission times, greater clarity on reception.
  • Repeater: less than time-out timer (3:00 TOT = 2:30 or less).


Use Mode Resolution TX Time
US Scottie 1 320x256 1:50
Europe Martin 1 320x256 1:54
DX Scottie DX 320x256 4:29
Quickest TX B/W 8 160x120 0:08
Longest TX P7 640x496 6:46
Highest Res PD290 800x616 4:49

As supported by MMSSTV.

Image Comparison

SSTV Color Test



BW 8

Image Comparison

SSTV Color Test


SSTV Robot 36

Robot 36

Image Comparison

SSTV Color Test


SSTV Scottie 1

Scottie 1

Image Comparison

SSTV Color Test


SSTV Scottie 2

Scottie 2

Image Comparison

SSTV Color Test


SSTV Scottie DX

Scottie DX

Signal Analysis: Header

  • 300ms leader tone at 1900 Hz 1.
  • 10 ms break at 1200 Hz 1.
  • Second (continued) 300ms leader tone at 1900 Hz 1.
  • 30ms VIS (Vertical Interval Signal) code identifying SSTV mode 2.
SSTV Signal Spectrogram

source & img: Wikipedia

SA: Scanlines

  • Horizontal lines scanned from left to right.
  • RGB color encoding, YC (Luminance & Chrominance), or black-and-white.
  • Modulating between 1500 Hz and 2300 Hz.
  • Signal frequency shifts up or down to designate brighter or darker pixels.
SSTV Signal Spectrogram

source & img: Wikipedia

SA: Sync

1200 Hz sync tone 5ms duration, after all line color components are sent 4.

SSTV is sensitive
Sensitive emoji
... to noise and sound card timings.

AVT mode has no sync tone!

SSTV Signal Spectrogram

source & img: Wikipedia

SSTV Software


Need a radio, computer, interface between the two, and software.

  • SignaLink USB (preferred).
  • Rigblaster.
  • Built in USB on newer HF radios.
  • Build your own connection.
  • Acoustic interface.

All audio/DSP enhancements must be disabled!

SignaLink USB

  • $120 for the SignaLink USB and connecting cable at ham retailer.
  • Connecting cable depends on radio.
  • Simple wiring instructions for radio and cable. Jumper modules available $10/ea, good using multiple radios.
  • W: 3.2 in., H: 1.6 in., D: 3.6 in. 0.40 lbs.
  • VOX. Computer audio triggers PTT.
SignaLink USB front SignaLink USB back
SignaLink USB connect diagram

img: F8DZY, W3YJ

Acoustic Interface

  • Doesn't require additional hardware.
  • Participate even without an interface.
Acoustic Interface

img: FLEMA

  • Receive data: hold radio to computer microphone.
  • Transmit data: hold radio to computer speakers.
  • PTT: manually.
  • Not an optimal setup.
  • Works poorly or not at all for some digital modes, requires more attention, and disruptive.

One More
Image Comparison

SSTV Color Test


SSTV Acoustic Interface using PD90

Acoustic Interface using PD90

Interface Quick Tips

  • Pet Peeve & PSA (to save you embarrassment): DO NOT leave the sound device as DEFAULT!!!
  • Troll
  • Your radio will transmit system sounds, music, screensaver noises, and anything else I send it.
  • Set both "Speaker" and "Microphone" volume levels to 50% (half) in Windows. Linux is good to 100%.
  • Disable all audio enhancements.
  • Test transmission on simplex channel with HT/scanner.
  • Detailed setup steps - includes recording and playback methods.
  • Advanced calibration.


  • Pro tip for HF & side-band operation.
  • Sound card timings are not as accurate as stated.
  • 11025 Hz might actually be 11027.12 Hz.
  • Causes the image to be received askew.
  • "Auto Slant" corrects, don't use on SSB.
  • Calibration: WWV (preferred) or another station.
Slant - extreme example

(Extreme Example)

img: WB9KMW


Template Station A Station B
(2) Call sign & RST report
(3) Send RST
*Can go back and forth with other images*
-Antennas, station info, etc.
(4) Send 73
(4) Send 73


Band Freq Mode
80 3845 kHz LSB
40 7170 kHz LSB
20 14230 kHz USB
15 21340 kHz USB
10 28680 kHz USB
6 50680 kHz USB
2 144.550 MHz USB
2 145.500 MHz FM

Find Out More

Stick around for

Simplex: 145.500

Reviewed setup and use of MMSSTV as documented here.


Jeffrey Kopcak - K8JTK

- ARRL Ohio Section Technical Coordinator
- This presentation is available on my website:
- Ohio Section