| 摘要 |
A voice amplification system for meeting rooms, teleconferencing and entertainment shows. A carrier with a predetermined frequency is generated and transmitted by a central unit, and acts as a base oscillation rather than a local oscillator for all the transmitters of the microphone units in the system. For this purpose, the central unit consists of two portions. The first portion comprises a local transmitter with a predetermined frequency for transmitting the common carrier, while the second portion comprises a receiver for receiving the signal transmitted by secondary units modulated according to the desired modulation. The secondary unit consists of three portions. The first portion comprises a receiver for picking up the common carrier signal for use as a base frequency during transmission, the second portion comprises a transmitter with a base frequency determined by the carrier frequency picked up by the combined receiver (first portion), and the third portion comprises a microphone for picking up a voice or audio signal to be transmitted. Said system enables simultaneous transmission by an unlimited number of microphone/transmitter units (wireless microphones) without any interference from frequency beating caused by two separate local oscillators, since two transmission signals with the same frequency and phase cannot be reproduced. This problem does not arise when mixing takes place on the audio signal instead of on the carrier. |
