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Subelement E2
OPERATING PROCEDURES
Section E2B
Television practices: fast scan television standards and techniques; slow scan television standards and techniques
How many times per second is a new frame transmitted in a fast-scan (NTSC) television system?
  • 30
  • 60
  • 90
  • 120

A frame consists of 2 fields, and fields are transmitted at almost 60 times per second (NTSC field refresh frequency is 60/1.001 Hz).

An entire frame is therefore transmitted 30 times per second.

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How many horizontal lines make up a fast-scan (NTSC) television frame?
  • 30
  • 60
  • 525
  • 1080

NTSC color encoding is used with the System M television signal, which consists of 29.97 interlaced frames of video per second. Each frame is composed of two fields, each consisting of 262.5 scan lines, for a total of 525 scan lines.

483 scan lines make up the visible raster. The remainder (the vertical blanking interval) allow for vertical synchronization and retrace.

The NTSC selected 525 scan lines as a compromise between RCA's 441-scan line standard (already being used by RCA's NBC TV network) and Philco's and DuMont's desire to increase the number of scan lines to between 605 and 800.

Source: Wikipedia

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How is an interlaced scanning pattern generated in a fast-scan (NTSC) television system?
  • By scanning two fields simultaneously
  • By scanning each field from bottom to top
  • By scanning lines from left to right in one field and right to left in the next
  • By scanning odd numbered lines in one field and even numbered lines in the next

Fast-scan television systems have two modes: progressive and interlaced. In progressive systems, the frame is scanned out completely, line-by-line. In interlaced systems, the odd-numbered lines are scanned out in one field, then the even-numbered lines are scanned out in the next field. When these two fields are interlaced back together, they make a complete picture.

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What is blanking in a video signal?
  • Synchronization of the horizontal and vertical sync pulses
  • Turning off the scanning beam while it is traveling from right to left or from bottom to top
  • Turning off the scanning beam at the conclusion of a transmission
  • Transmitting a black and white test pattern

On a CRT monitor, if the beam was left on while returning from the end of one scan line or field to the beginning of the next, the entire diagonal line of pixels would be partially illuminated. During the blanking interval, the beam is turned off long enough to travel to the start of the next line or field without accidentally illuminating any pixels.

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Which of the following is an advantage of using vestigial sideband for standard fast- scan TV transmissions?
  • The vestigial sideband carries the audio information
  • The vestigial sideband contains chroma information
  • Vestigial sideband reduces bandwidth while allowing for simple video detector circuitry
  • Vestigial sideband provides high frequency emphasis to sharpen the picture

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.

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What is vestigial sideband modulation?
  • Amplitude modulation in which one complete sideband and a portion of the other are transmitted
  • A type of modulation in which one sideband is inverted
  • Narrow-band FM modulation achieved by filtering one sideband from the audio before frequency modulating the carrier
  • Spread spectrum modulation achieved by applying FM modulation following single sideband amplitude modulation

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. (E2B06) 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. (E2B05)


Hint: Vestigial means a small part or portion of something larger.

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What is the name of the signal component that carries color information in NTSC video?
  • Luminance
  • Chroma
  • Hue
  • Spectral Intensity

The Chroma (color) signal is sent as a sub-carrier modulating the main luminance (brightness) signal.

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Which of the following is a common method of transmitting accompanying audio with amateur fast-scan television?
  • Frequency-modulated sub-carrier
  • A separate VHF or UHF audio link
  • Frequency modulation of the video carrier
  • All of these choices are correct

All of these choices are correct. The following are all common methods of transmitting accompanying audio with amateur fast-scan television.

Frequency modulation of the video carrier

A separate VHF or UHF audio link

Frequency-modulated sub-carrier

-KE0IPR

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What hardware, other than a receiver with SSB capability and a suitable computer, is needed to decode SSTV using Digital Radio Mondiale (DRM)?
  • A special IF converter
  • A special front end limiter
  • A special notch filter to remove synchronization pulses
  • No other hardware is needed

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, is needed to decode SSTV using Digital Radio Mondiale (DRM)

-KE0IPR

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Which of the following is an acceptable bandwidth for Digital Radio Mondiale (DRM) based voice or SSTV digital transmissions made on the HF amateur bands?
  • 3 KHz
  • 10 KHz
  • 15 KHz
  • 20 KHz

Remember that SSTV (Slow Scan TV) transmissions have to fit into the same bandwidth as common SSB voice transmission.

-benny2

Just like any SSTV transmission, 3 KHz is an acceptable bandwidth.

Answer: 3KHz

-KE0IPR

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What is the function of the Vertical Interval Signaling (VIS) code sent as part of an SSTV transmission?
  • To lock the color burst oscillator in color SSTV images
  • To identify the SSTV mode being used
  • To provide vertical synchronization
  • To identify the call sign of the station transmitting

From Wikipedia here https://en.wikipedia.org/wiki/Slow-scan_television

A calibration header is sent before the image. It consists of a 300-millisecond leader tone at 1900 Hz, a 10 ms break at 1200 Hz, another 300-millisecond leader tone at 1900 Hz, followed by a digital VIS (vertical interval signaling) code, identifying the transmission mode used. The VIS consists of bits of 30 milliseconds in length. The code starts with a start bit at 1200 Hz, followed by 7 data bits (LSB first; 1100 Hz for 1, 1300 Hz for 0). An even parity bit follows, then a stop bit at 1200 Hz. For example, the bits corresponding the decimal numbers 44 or 32 imply that the mode is Martin M1, whereas the number 60 represents Scottie S1.

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How are analog SSTV images typically transmitted on the HF bands?
  • Video is converted to equivalent Baudot representation
  • Video is converted to equivalent ASCII representation
  • Varying tone frequencies representing the video are transmitted using PSK
  • Varying tone frequencies representing the video are transmitted using single sideband

SSTV is similar to facsimile except that sync pulses are sent. SSTV is undergoing a resurgence due to the use of PCs and other hardware. The bandwidth requirements are modest and so long distance SSTV on the HF bands is possible.

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How many lines are commonly used in each frame of an amateur slow-scan color television picture?
  • 30 or 60
  • 60 or 100
  • 128 or 256
  • 180 or 360

https://en.wikipedia.org/wiki/Slow-scan_television#Scanlines
Slow-scan television (SSTV) is a picture transmission method used mainly by amateur radio operators, to transmit and receive static pictures via radio in monochrome or color.

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What aspect of an amateur slow-scan television signal encodes the brightness of the picture?
  • Tone frequency
  • Tone amplitude
  • Sync amplitude
  • Sync frequency

The tone frequency of an amateur slow-scan television signal encodes the brightness of the picture.

SSTV uses analog frequency modulation, in which every different value of brightness in the image gets a different audio frequency. In other words, the signal frequency shifts up or down to designate brighter or darker pixels, respectively.

Color is achieved by sending the brightness of each color component (usually red, green and blue) separately. This signal can be fed into an SSB transmitter, which in part modulates the carrier signal.

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What signals SSTV receiving equipment to begin a new picture line?
  • Specific tone frequencies
  • Elapsed time
  • Specific tone amplitudes
  • A two-tone signal

Although we are called “radio” amateurs, we can also send and receive television signals. There are several ways that amateurs communicate by television. Perhaps the two most popular ways are standard fast-scan television and slow-scan television (SSTV).

128 or 256 lines are commonly used in each frame on an amateur slow-scan color television picture. (E2B13) Specific tone frequencies signal SSTV receiving equipment to begin a new picture line (E2B15).

Source: Extra Class question of the day: Television practices: fast scan television standards and techniques; slow scan television standards and techniques

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Which is a video standard used by North American Fast Scan ATV stations?
  • PAL
  • DRM
  • Scottie
  • NTSC

The answer is NTSC

PAL(Phase Alternating Line) was developed by Walter Bruch for European use when those countries were planning the introduction of colour TV.

DRM stands for Digital Radio Mondiale, a digital mode for encoding voice and SSTV. It is an open standard. (While DRM commonly means Digital Rights Management to most people, that is not its meaning in the amateur radio arena.)

Scottie is a common mode for encoding SSTV transmissions.

NTSC(National Television System Committee) is the TV system used in North America and various other countries for analog broadcasts.

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What is the approximate bandwidth of a slow-scan TV signal?
  • 600 Hz
  • 3 kHz
  • 2 MHz
  • 6 MHz

http://en.wikipedia.org/wiki/Slow-scan_television

The key word is slow. You might mistakenly choose 6 MHz which is the analog TV bandwidth required to send 25 to 30 frames per second. In contrast, slow-scan at 3 kHz bandwidth takes from eight seconds to a couple of minutes to transmit a single frame.

Also, Slow-Scan is typically sent on HF and HF signals are typically limited to no more than 3 KHz or a normal voice channel.

[Possible gimmick hint: sLOW TV = LOWest VHF TV channel on most tuners is 3]

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On which of the following frequencies is one likely to find FM ATV transmissions?
  • 14.230 MHz
  • 29.6 MHz
  • 52.525 MHz
  • 1255 MHz

In North America, the 70cm, 33cm, and 23cm bands are typically used for ATV. (See Amateur television on Wikipedia.)

So for this question, 1255 MHz (23cm band) is the most likely frequency to find FM ATV transmissions.

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What special operating frequency restrictions are imposed on slow scan TV transmissions?
  • None; they are allowed on all amateur frequencies
  • They are restricted to 7.245 MHz, 14.245 MHz, 21.345 MHz, and 28.945 MHz
  • They are restricted to phone band segments and their bandwidth can be no greater than that of a voice signal of the same modulation type
  • They are not permitted above 54 MHz

Slow scan TV uses a similar amount of bandwidth to SSB phone (voice) transmissions, so it is allowed on the same band segments (except 60 meters).

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