Communication system which dynamically switches sizes of sample buffer between first size for quick response time and second size for robustness to interrupt latency

Abstract

An apparatus for and method of implementing a novel buffer ba full duplex communication system is disclosed. The disclosed invention is particularly useful in native sign processing systems wherein heavy contention of processor resources typically exist, such as in systems running multi-tasking operating systems. The communication system of the present invention includes a receiver, transmitter, echo canceler. CODEC and telephone hybrid. The major components of the system operate on a buffer of input samples consisting of a set of input bits. The communications system operates to generate a buffer of output samples consisting of a set of output bits. The invention utilizes a novel buffer switching mechanism to optimize the tradeoff between processing response time, on one hand, and robustness to interrupt latency and processor implementation on the other hand. The internal processing of the modem works on a buffer full of samples once every time slice thus reducing the probability of a buffer underrun/overrun error occurring. The reduction in probability of data underrun/overrun is achieved by increasing the buffer size, thus giving the operating system greater leeway in choosing the exact time the signal processing functions are run. Small buffers, however, provide the communication system with short and accurate response time. These contradicting motives lead to the novel switchable size buffer scheme of the present invention. This is achieved without a loss of signal coherency.