TELEVISION SYSTEM (TV)

Analog Broadcasting Television:-

There are three analog broadcasting television (TV) systems.

(PAL), (NTSC) and (SECAM) Commercial (TV) Broadcasting systems.

Commercial (TV) Broadcasting began as black and white picture transmission in London in (1936) by the British Broadcasting Corporation (BBC) the British standard was set by the (PAL) (Phase Alternating Line)(TV).

The French standard was set by the (SECAM), (Sequentially Encoding Color Alternating Modulation) (TV).

In construct to radio broadcasting, standards for Television signal transmission vary from country to country.

The United State America (USA) standard which we describe below was set by the (National Television systems committee) (NTSC) (TV).

Color Television was demonstrated a few years later, but the move of commercial (TV) signal, transmission was slow in developing to large extended this was due to the High cost of color (TV) receivers with the deployment of the Transistor and Microelectronics component, the cost of color (TV) receivers decreased significantly, so that by the middle (1960s) color (TV) Broadcasting was widely used By the Industry.

The frequencies allocated for (TV) Broadcasting fall in the (VHF) and (UHF) frequency bands:-

1- Band –I: Frequency (41 MHZ – 68 MHZ) four channels (1, 2, 3, and 4).

2- Band –II: Lower (VHF) (88 MHZ – 108 MHZ) for (FM) Radio Broadcasting.

3- Band - III : Upper (VHF) (174 MHZ – 230 MHZ) Eight – channels (5, 6, 7, 8, 9, 10, 11, 12)

4- Band – IV: Lower (UHF) ( 470 MHZ – 582 MHZ) Sixteen – channels (21, 22, 23, ….. 36)

5- Band – V: Upper (UHF) ( 606 MHZ – 870 MHZ) Thirty three channels ( 37, 38,…. 69)

Note:

- Band–II: Lower (VHF) (88 MHZ–108 MHZ) don't use in (TV), because it is used in (FM) transmission and other application.

- Band–I and Band–III of very high frequency range has been used for various television channels, which is very clear from the shown above the difference of frequency range between every channel is (7 MHZ) for (PAL) first channel number (No-1 to 4) is not used for television

transmission as it's bandwidth frequency rang is only (6 MHZ) and for television transmission band of at least (7 MHZ) is required.

For British Standard System (PAL):-

1- For every channel there is a different of (5.5 MHZ) between Picture carrier frequency and Sound carrier frequency.

2- Between each channel there is a difference of (7 MHZ) in the frequency range, it is bandwidth channel of system (PAL) (TV), frequency band or bandwidth channel.

Picture and Sound carrier frequency of any channel can be calculated as shown:

- Picture carrier frequency = minimum frequency of channel width frequency (+1.25MHZ)

- Sound carrier frequency = maximum frequency of channel (- 0.25MHZ)

The clear from the shown above, we can calculated a value of Vision or Picture carrier frequency and value of Sound carrier frequency of various channels contained in (Band – III, Band – IV and Band – V of ultra high frequency range).

Example:

Band – III- (channel NO – 10).

Bandwidth = (209 MHZ – 216 MHZ).

- Picture or Vision carrier is (minimum frequency) = 209 MHZ + 1.25MHZ = 210.25 MHZ.

- Sound carrier is (maximum frequency) = 216 MHZ - 0.25 = 215.75MHZ

Difference between picture carrier frequency and sound carrier frequency = 5.5 MHZ.

Constant value = 215.75MHZ – 210.25 MHZ = 5.5 MHZ.

The frequency range of ultra high frequency (UHF) is (470 MHZ – 870 MHZ) and a total number of (49) channels come under this range.

In (band – IV) of ultra high frequency there are a total of (16) channels, each of channel width (7 MHZ) and the frequency range is (740 MHZ to 582 MHZ), similarly in (band –V) there are (33) channels, each of bandwidth (8 MHZ) and frequency range is (606 MHZ to 870 MHZ).

The system (PAL) has (625) lines for scanning the screen and carrier for color equal

(4.43 MHZ) the carrier of sound at picture carrier frequency (5.5 MHZ), the field scanning (50 MHZ).

For America (USA) Standard System (NTSC):-

The system (NTSC), the (TV) channel allocation in America (USA), we observe that the channel bandwidth allocated for transmission of (TV) signals is (6 MHZ), the difference between Picture carrier frequency and Sound carrier frequency equal (4.5 MHZ), the sound carrier (4.5 MHZ), the chrominance carrier or color carrier (3.57 MHZ) has (525) line, for scanning (TV) screen, the field scanning frequency (60 MHZ).

For French Standard System (SECAM):-

The System (SECAM), the (TV) channel allocation in French we observe that the channel bandwidth allocated for transmission of (TV) signal is (8 MHZ), the difference between Picture carrier frequency and Sound carrier frequency equal (4.40 MHZ), this system has (625) lines for scanning (TV) , the field scanning frequency (50 HZ).

The system High Definition Television (HDTV):

The (TV) allocations in all world we observe that the channel bandwidth allocated for transmission of (TV) , on this new system (TV).

1- (6.0 MHZ)– Systems (M, N, NTSC and PAL).

2- (7.0 MHZ) – System (B-SECAM and PAL).

3- (8.0 MHZ) –System (O, H, I, D, K, KI, L, SECAM and PAL).

In (1986) start working in this new system. In (1992) the united state can use old system Television (NTSC), with (525) lines for scanning transmission digital (HDTV). After that the Sweden) can use old system channel (SECAM) (626) for scanning, for transmission Digital (HDTV).

Transmission symbol signal (0.8 – 1.2 G bit/s) in system high quality equal (2.0 – 3.0 G bit/s), there are in the (HDTV) (1125) Line for scanning and (60 HZ) the field scanning frequency.

The Japanese, can use (1250) Lines for scanning and the field scanning frequency (50 HZ)

In kind of use (Pixels) in Horizontal and Vertical (1920 X 1080) (2:1), with frequency of (74.25 MHZ) we can use it with (50 HZ) and (60 HZ) by (1080 X 1920) (16:9 ≈ (4:3), 1080 active line in picture (1920) activity part lines.

Digital Broadcasting Television:-

There are three systems in the digital Broadcasting Television.

1- ATSC –T: Advanced Television Systems Committee –Television.

2- DVB –T: Digital Video Broadcasting –Television.

3- ISDB –T: Integrate Services Digital Broadcasting –Television.

We can transmission at four to ten signals (TV) program in one channel by using compress information, five of ten is high quality.

High quality than analog, we can transmission high information with very velocity in (small time).

Digital Television standard (ATSC):

The (ATSC) (TV) channel allocation in (USA), we observe that the channel bandwidth allocated for transmission of (TV) digital signal is (6 MHZ) and (8 MHZ) (5.38 MHZ) and (7 MHz).

Radiation carrier (1), active carrier (1)

Type of modulation (8-VSM)

Limit time active element (92.9 ns), limit complete symbol (T) (77.3 MHz)

Time (TX), picture (48.54 µs), velocity data (19.392 M bit/s)

Signal to noise ratio (S/N) channel (19.9 dB)

Active carrier (1)

For (8 MHZ) and (7 MHZ).

Active carrier (1)

Type of modulation (8-VSB)

Time active system symbol (71,4 ns)

Time completes (49.4 µs), time (TX) picture (37.2 µs)

Signal to noise ratio S/N channel (15.19 dB).

Digital Television standard (DVB):

DVB–T, digital television standard the (TV) (DVB–T) channel allocation in European, we

observe that the channel bandwidth allocate for transmission of (TV) digital signal is.

(6 MHZ) and (8 MHZ), (5.74 MHZ) and (7.608 MHZ),

There are two systems one for (system – 2K) and the other for (system – 8K).

Radiation carriers (1705– S-2K), (6817– S-8K),radiation carriers (1512– S-2K) (6048– S-8K)

Type modulation (OFDM, QPSK, 16-QAM, 64 – QAM, MR-16, QAM, MR-64, QAM).

Time active symbol (224 µs– S-2K ) (896 µs– S-8K)

Different between carriers (4464 KHZ – S -2K), (1116 KHZ – S-8K).

Time complete symbol (231, 238, 252, 280 µs – S-2K), (924,952, 1008, 1120 µs – S-8K).

Time (TX) picture (68 OFDM symbol one specter include is (4) pictures.

Velocity use full data (4.98–31.67 M bit /s) signal to noise ratio (S/N) in channel (3.1–20.1 dB).

Digital Television Standard ( ISDB-T):

The (ISDB–T) (TV) channel allocation in Japan we observe that the channel bandwidth allocated for transmission of (TV) digital signal is (6 MHZ) and (8 MHZ); (5.57 MHZ, S –1) (5.57 MHZ, S – 2), (5.57 MHZ, S – 3) and there are three systems (S-1, S-2 and S-3), (6 MHZ).

(7.434 MHZ, S -1), (7.431 MHZ, S – 2), (7.430 MHZ, S – 3)

Radiation carriers (1405, S-1); (2809, S – 2), (5617, S – 3).

Method modulation Type: (OFDM, D-QPSK, QPSK, 16-QAM, 64 –QAM)

Time active symbol (1189 µs, S – 1) ; ( 378 µs, S – 2 ) ; ( 5291 µs, S-1) ; ( 1322 µs, S -3)

Time complete symbol ( 236, 250, 212, 625, 200, 813, 194,906 µs, S-1),

Time (TX) picture (204 OFDM symbols) signal to noise ratio S/N in channel (6.2 – 22.0 dB).