| 摘要 |
<p>1505358 Stereophonic receivers MOTOROLA Inc 18 March 1975 [28 March 1974] 11218/75 Heading H4R A composite stereo signal 74 is demodulated by multiplication 80, 82 with a decoding signal to produce a differential sub-channel (difference) signal which is amplified in a differential amplifier 108, 110 to produce antiphase sub-channel signals which are then combined in a matrix 92, 94 with the composite signal (via lines 91, 93) to produce left and right audio information, the multiplier 80, 82 being shorted during monaural signal reception to prevent sub-channel signals reaching the matrix. The circuit of Fig. 2 may be modified by having a common 38 kHz demodulating carrier feeding opposite conductivity type transistors 80, 83 and the composite signal may be fed as a common mode signal via a resistive-T network for mixing with the sub-channel signals (Fig. 4, not shown).</p> |
