Tesis previa a la obtención del Título de Ingeniero en Electrónica y ...

- voice encoded at 56 kb¡t/s with a bandwidth 50 to 7000 Hz (subband ADPCM according to
Recommendation G.722); the coding algorithm is also able to work at 48 kbit/s - data can then be
dynaraically inserted at up to 14.4 kbit/s;
— still pictures coded at 56 kbit/s;
- data at 56 kbit/s inside an audiovisual session (e.g. file transfer for communicating between personal
computéis).
125 microseconds
1 2 3 4 S 6 7 6/1-2 6/7-1 6/1
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Frame alignment
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Audio 4- serv¡C9 channel
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FAS
BAS
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H0 n- 1
Ht1 n - 4
H12 n = 5
1 Oclel number
:
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:
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FIGURE 2/H.221
Frame structure of higher-rate single channels
(H0, Hll3 H12 channels)
General
80-octet frame length produces an 80-bÍt word in the service channel. These 80 bits are numbered 1-80. Bits 1-8 of
service channel in every frame constitute the FAS (see Figure 3), whose contení ís as follows:
- multíframe structure (see 2.2);
- Frame alignment word (FAW);
- A-bit;
E- and C-bits (see 2.6).
17
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80
Recommendation H.221 (03/93)