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650<br />

Wire and Wireless Communication Applications Chap. 8<br />

TABLE 8–14<br />

U.S. ATSC SYSTEM<br />

Video specifications<br />

Format type HD HD SD SD SD<br />

Aspect ratio 16:9 16:9 4:3 16:9 4:3<br />

Active scan<br />

linesframe 1080 720 480 480 480<br />

Pixels/line 1920 1280 704 704 640<br />

Frame rates<br />

(Hz) a 24p, 30p, 30i 24p, 30p, 60p 24p, 30p, 30i, 60p 24p, 30p, 30i, 60p 24p, 30p, 30i, 60p<br />

Compression standard b<br />

Compression technique c<br />

MPEG-2<br />

DCT, 8 × 8 block<br />

Audio specifications<br />

Method<br />

Dolbey AC-3<br />

Audio bandwidth<br />

20 kHz<br />

Sampling frequency<br />

48 kHz<br />

Dynamic range<br />

100 dB<br />

Number of surround channels d 5.1<br />

Compressed data rate<br />

384 kb><br />

s<br />

Multiple languages<br />

Via multiple AC-3 data streams<br />

Data transport system<br />

Type<br />

TDM technique<br />

Packet size<br />

Packet header size<br />

Encryption<br />

Special features support<br />

Packet<br />

MPEG-2, system layer<br />

188 bytes<br />

4 bytes<br />

Provision descrambling by authorized decoders<br />

Closed captioning and private data<br />

Transmission specifications for terrestrial mode broadcasting e<br />

Modulation f<br />

8VSB<br />

Bits> symbol<br />

3<br />

Channel bandwidth<br />

6 MHz<br />

Channel filter Raised cosine-rolloff, r = 0.115><br />

2 = 0.0575<br />

Symbol (baud) rate (with sync)<br />

10.76 Msymbols><br />

s<br />

Payload data rate (with sync)<br />

19.39 Mb><br />

s<br />

Coding (FEC)<br />

Rate 2><br />

3 TCM and (207,187) Reed-Solomon<br />

CNR threshold 14.9 dB for a BER of 3 × 10 -6<br />

Pilot (for carrier sync)<br />

310 kHz above lower band edge of RF channel<br />

a p = progressive scan, i = Interlace scan.<br />

b MPEG = Moving Picture Experts Group of the International Standards Organization (ISO).<br />

c DCT = Two-dimensional (horizontal and vertical) Discrete Cosine Transform taken over an 8 × 8 block of pixels.<br />

The insignificant DCT values are ingored to provide data compression.<br />

d Left, center, right, left surround, right surround, and subwoofer. The sixth (subwoofer) channel contains only low audio<br />

frequencies so it is considered to be a 0.1 channel.<br />

e Terrestrial mode is for off-the-air broadcasting. For transmission via CATV, 16 VSB may be used. This allows a higher<br />

payload data rate of 38.6 Mbitssec over a 6-MHz bandwidth channel. However, a minimum (CNR) of 28.3 dB is required.<br />

f 8VSB = 8 level Vestigial Sideband Modulation. That is, an 8 level baseband line code is amplitude modulated onto a<br />

suppressed carrier (DSB-SC) signal, and the lower sideband is filtered off to produce the VSB signal.

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