| 摘要 |
PCT No. PCT/DK86/00131 Sec. 371 Date Aug. 4, 1987 Sec. 102(e) Date Aug. 4, 1987 PCT Filed Dec. 4, 1986 PCT Pub. No. WO87/03771 PCT Pub. Date Jun. 18, 1987.By a method and a circuit for the purpose of decoding four-channel signals coded in a matrix and available in the form of a two-channel signal, whereby in each channel an automatic control of the amplification will take place by means of an output amplifier ( DELTA L, DELTA R, DELTA B, DELTA C) in the output stage in question, it is proposed that the differential signal is conducted both to a delay circuit ( DELTA T) and then to an expander circuit (EXP), and also to a central rectifier element (D1), that the output signal (UCD) form the rectifier circuit (D1, CA, CD) is both conducted to the expander circuit (EXP) and applied for controlling the channels in pairs, whereby the stereo channels are controlled in phase and the center and background channels in reversed phase of the mean value (UCD) of the differential signal, and that all channels moreover adjusted both in phase to the DC component of the summation signal amplitude and also in accordance with a level chosen in advance. |
