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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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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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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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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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.

Hint: Only the correct answer has 2 "V"s in it "V"estigial and "V"ideo

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

Trick to remember: Component that Carries Color is Chroma

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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

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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)

Hint- Three words to match DRM - "Doesn't Require More"

Hint 2: If the computer in question is "suitable," then it won't need any help besides the receiver with SSB capabilities.

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

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

Answer: 3KHz

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Trick to remember: VIS CODE identifies MODE

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 to the decimal numbers 44 or 32 imply that the mode is Martin M1, whereas the number 60 represents Scottie S1.

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Trick to remember:

Varying Tones Single Sideband (SSTV backwards)

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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.

Its the only answer with very specific numbers

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

SSTV (Slow Scan Television) 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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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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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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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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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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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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