| 摘要 |
PURPOSE:To express stereophonic sense by passing an IF signal through a broad band pass filter at the stereophonic mode and applying the signal to an IF amplifier to ensure the level of a high frequency sound. CONSTITUTION:When a pilot signal is detected by an AM stereophonic recorder 7, diodes D2, D4 in an IF filter selection circuit 5 are turned on and diodes D1, D2 are turned off and the broad band pass filter F2 is selected. As a result, the IF signal from a mixing circuit 3 is fed to the IF amplifier 6 via the filter F2. In this case, a switch circuit 19 is operated in the decoder 7 to form the stereophonic mode, and a matrix circuit receives a difference signal from a synchronous detector via the switch circuit 19 and a sum signal from an envelope detector, and processes the result and L/R sound signals are outputted respectively from output terminals 22L, 22R. |
