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.

Technical Coordinator

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.

http://www.arrl.org/technical-specialist

SSTV...

...stands for Slow-Scan TV.

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

SSTV...

• 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...

Though similar names, completely different.

History

• 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

History

• Used an electrostatic monitor and 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.

• 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 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

img: Martin Bruchanov

img: Martin Bruchanov

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.

Modes

• 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).

Modes

As supported by MMSSTV.

Image Comparison

Original

BW 8
8s

Image Comparison

Original

Robot 36
36s

Image Comparison

Original

Scottie 1
1:50

Image Comparison

Original

Scottie 2
1:11

Image Comparison

Original

Scottie DX
4:29

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.

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.

source & img: Wikipedia

SA: Sync

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

SSTV is sensitive

... to noise and sound card timings.

AVT mode has no sync tone!

source & img: Wikipedia

Interfaces

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.

img: F8DZY, W3YJ

Acoustic Interface

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

Original

Acoustic Interface using PD90
1:30

Interface Quick Tips

• Pet Peeve & PSA (to save you embarrassment): DO NOT leave the sound device as DEFAULT!!!

• 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.

Slant

• 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)

img: WB9KMW

QSO

Frequencies