| 摘要 |
PROBLEM TO BE SOLVED: To improve an S/N ratio. SOLUTION: A stereo modulator 10 converts an audio signal S1 to a stereo composite signal S2. A frequency modulator 20 receives the stereo composite signal S2 and modulates the frequency of a carrier wave using the stereo composite signal S2 as a modulation signal. An amplitude modulator 15 modulates the amplitude of a sub-carrier by using, as a modulation signal, a difference signal L-R between an L-channel and an R-channel. A first adder 16 adds an output of the amplitude modulator 15 with a sum signal L+R of the L-channel and R-channel. A first multiplier 17 multiplies an output of the first adder 16 with a first variable coefficientα. A second multiplier 18 multiplies a pilot signal S5 with a second variable coefficientβ. A second adder 14 adds outputs of the first and second multipliers 17 and 18 and outputs the resultant. A modulation degree adjuster 32 adjusts the amplitude of the stereo composite signal S2 and outputs the resultant signal to the frequency modulator 20. COPYRIGHT: (C)2008,JPO&INPIT
|
