Complex signal generation and transmission

摘要

Disclosed is an apparatus for and a method of complex signal generation and transmission having particular application in a time assigned speech interpolation or TASI system. Samples of the amplitudes of a plurality of signalling status and test signals are stored in a digital code in a digital memory. These samples are retrieved as needed without the need for a plurality of time base signal generating means. The signal to noise ratio of the signals to be transmitted is increased by statistically predicting the n equally likely amplitude ranges of the entire set of signals. Each character of the digital code employed identifies one of these ranges. The more likely occurring amplitudes are thus defined by more code characters than are the less likely amplitudes. Additionally, the signal to noise ratio of the entire set of signals is increased while minimizing the digital storage requirements of the system by the provision of a second digital memory for storing a single amplitude within each of the above-mentioned ranges. The samples stored in the first memory are used as index vectors which identify and select the single amplitudes stored in the second memory which are then transmitted to the receive side of a TASI system. Since the second memory is 2 x bits wide, while the index vectors are stored in a memory only X bits wide, digital storage requirements are minimized.