公开(公告)号：JPH10178323A

公开(公告)日：1998-06-30

申请号：JP29428397

申请日：1997-10-27

Applicant: KOREA ELECTRONICS TELECOMM ,  KOREA TELECOMMUN

Inventor： SEI RAKUZEN ,  KAN TOKI

IPC: H03G3/20 ,  H04L27/00

Abstract: PROBLEM TO BE SOLVED: To improve BER performance and to prevent the loss of carrier wave synchronization in environment where a receiving state rapidly and frequently changes by reducing the frequency of first automatic gain control causing the level fluctuation of an input signal to a demodulator. SOLUTION: At the same time of executing second automatic gain control processing to the output signal of a first AGC circuit, a first AGC circuit receives the input of a next received signal an executes first automatic gain control processing to this received signal (S16). Then the intensity of the output signal of the first AGC circuit is measured by a detection circuit (S17). After then, a microprocessor judges whether the measured value is within the second power control window W3 of an already decided band width larger than a first power control window W2 (S18). Then when the measured value is not within the second power control window W3, the microprocessor corrects the gain of the first AGC circuit (S19).

公开(公告)号：JPH10178623A

公开(公告)日：1998-06-30

申请号：JP22799697

申请日：1997-08-25

Applicant: KOREA ELECTRONICS TELECOMM ,  KOREA TELECOMMUN

Inventor： KAN TOKI ,  SAI SOSEKI

IPC: H04N7/08 ,  H04H20/00 ,  H04H20/74 ,  H04H60/07 ,  H04H60/15 ,  H04H60/23 ,  H04L9/18 ,  H04L9/36 ,  H04N7/081 ,  H04N7/20 ,  H04H1/00

Abstract: PROBLEM TO BE SOLVED: To reduce costs to acquire stability and reliability by separately providing a circuit which makes a compressed data stream a system packet and a scrambling control circuit to the circuit in accordance with each channel of audio and video and later multiplexing it. SOLUTION: In a channel scrambling part 200, MPEG 2 system packet stream generating parts 210 and 240 generate a system packet for each channel of video and audio. Scramblers 230 and 260 scramble a payload part with a control word of each channel of video and audio as a key. For instance, on the video channel side, when the part 210, a scramble ON/OFF path controller 220, the scrambler 230 are formed in one module, the timing control of a circuit operation is simple and design is easy in each module.