| 摘要 |
<p>A signal transmission system features a transmitting station which includes an encoder for sampling an analog audio signal or a difference between an analog audio signal and a comparison signal to convert it into a digital audio signal, which is represented by n bits (n ? 2) for one sampling. The digital audio signal is processed by a multi-level former into a signal having 2n different levels and this signal is transmitted after modulation. At a receiving terminal, the 2n-level signal is demodulated and converted by a level discriminator into the digital audio signal. The digital audio signal is applied to a decoder to reproduce an analog audio signal. The system requires no frame sync signal and, thereby, enables audio information to be transmitted with a 100% efficiency, which offers the reproduced audio signal with desirable quality. Provision of parallel-to-serial and serial-to-parallel converters is unnecessary and, in addition, the receiving terminal does not require a frame sync signal reproducing circuit since it needs a clock signal only. This simplifies construction and facilitates completion of the synchronizing system and, accordingly achieves improvements both in performance and in economy.</p> |
