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2020 Extra Class study guide: E2B - Television practices: fast scan
television standards and techniques; slow scan television standards and
techniques

Posted: 03 Apr 2020 07:25 AM PDT
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Although we are called “radio� amateurs, we can also transmit and receive
television signals. There are several ways that amateurs communicate by
television. Two of the most popular ways send and receive television
signals are standard fast-scan television and slow-scan television (SSTV).

The video standard used by North American fast-scan ATV stations was
established by the National Television Systems Committee (NTSC) and was
used for television systems in the U.S. and many other parts of the world.
After nearly 70 years of using the analog NTSC system, U.S. broadcasters
switched over to a digital broadcasting system on June 12, 2009.

A fast-scan (NTSC) television frame has 525 horizontal lines, and a new
frame is transmitted 30 times per second in a fast-scan (NTSC) television
system. NTSC systems use an interlaced scanning pattern. An interlaced
scanning pattern is generated in a fast-scan (NTSC) television system by
scanning odd numbered lines in one field and even numbered ones in the next.

Fast-scan television operation normally occurs on the 70 cm band. The
reason for this is that the band is wide enough to accommodate the 6-MHz
wide signal and commercial analog TV receivers can be used to receive the
signals. The transmissions occur on channels shared with cable TV.
QUESTION: How many horizontal lines make up a fast-scan (NTSC) television
frame? (E2B02)

ANSWER: 525
QUESTION: How many times per second is a new frame transmitted in a
fast-scan (NTSC) television system? (E2B01)

ANSWER: 30
QUESTION: How is an interlaced scanning pattern generated in a fast-scan
(NTSC) television system? (E2B03)

ANSWER: By scanning odd numbered lines in one field and even numbered lines
in the next
QUESTION: What technique allows commercial analog TV receivers to be used
for fast-scan TV operations on the 70 cm band? (E2B08)

ANSWER: Transmitting on channels shared with cable TV

NTSC signals are amplitude modulated (AM) signals, but use a technique
called vestigial sideband modulation. Vestigial sideband modulation is
amplitude modulation in which one complete sideband and a portion of the
other are transmitted. The reason that NTSC TV uses vestigial modulation is
to conserve bandwidth. Even using this technique, an NTSC signal is 6 MHz
wide. One advantage of using vestigial sideband for standard fast- scan TV
transmissions is that vestigial sideband reduces bandwidth while allowing
for simple video detector circuitry.
QUESTION: What is vestigial sideband modulation? (E2B06)

ANSWER: Amplitude modulation in which one complete sideband and a portion
of the other are transmitted
QUESTION: Which of the following describes the use of vestigial sideband in
analog fast-scan TV transmissions? (E2B05)

ANSWER: Vestigial sideband reduces bandwidth while allowing for simple
video detector circuitry

Amateurs can transmit color TV as well as black-and-white TV. In a color TV
signal, the color lines are sent sequentially. The name of the signal
component that carries color information in NTSC video is chroma.
QUESTION: How is color information sent in analog SSTV? (E2B04)

ANSWER: Color lines are sent sequentially

QUESTION: What is the name of the signal component that carries color
information in NTSC video? (E2B07)

ANSWER: Chroma
Slow-scan TV (SSTV)

SSTV images are typically transmitted on the HF bands using single
sideband. Because of this, amateurs can only operate SSTV in the phone
portions of the HF bands, and the bandwidth of the SSTV signal can be no
greater than a normal SSB signal. The tone frequency of the single sideband
signal determines the brightness of the picture, and specific tone
frequencies signal SSTV receiving equipment to begin a new picture line.
QUESTION: What aspect of an analog slow-scan television signal encodes the
brightness of the picture? (E2B10)

ANSWER: Tone frequency
QUESTION: What signals SSTV receiving software to begin a new picture line?
(E2B12)

ANSWER: Specific tone frequencies

There are a number of different SSTV modes. The function of the Vertical
Interval Signaling (VIS) code transmitted as part of an SSTV transmission
is to identify the SSTV mode being used.
QUESTION: What is the function of the Vertical Interval Signaling (VIS)
code sent as part of an SSTV transmission? (E2B11)

ANSWER: To identify the SSTV mode being used

Digital Radio Mondiale is one way to send and receive SSTV signals. No
other hardware is needed, other than a receiver with SSB capability and a
suitable computer, to decode SSTV using Digital Radio Mondiale (DRM).
QUESTION: What hardware, other than a receiver with SSB capability and a
suitable computer, is needed to decode SSTV using Digital Radio Mondiale
(DRM)? (E2B09)

ANSWER: No other hardware is needed

The post 2020 Extra Class study guide: E2B Television practices: fast scan
television standards and techniques; slow scan television standards and
techniques appeared first on KB6NUs Ham Radio Blog.