| 摘要 |
<p>A telephone interconnection system, is designed to remove the need for high performance filters normally required in frequency division based multiplexes and overcomes the problems associated with synchronous demodulation in the case of twin band demodulation. Multiplexing is accomplished by frequency division and requires a modulator providing a voice amplitude modulated signal or a variable frequency carrier wave and a synchronised demodulator which receives such signals. The modulator employs two frequency multiplication states fed in phase quadrature from the voice signal and an addition circuit providing the output. The demodulator has a further two multipliers fed in parallel followed by extraction of the voice signal by a quadrature dephasing circuit.</p> |
