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Multiple Pseudo-Synchronous Processes Time Multiplexing in a Single Signal Processor

IP.com Disclosure Number: IPCOM000042971D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

Belloc, J: AUTHOR [+2]

Abstract

Many realtime applications in signal processing consist of several pseudo-synchronous processes. Pseudo-synchronous processes are processes which must be run periodically, with very slight differences between their periods. A typical example is the transmitter and the receiver of a modem. Under a certain condition (processing time condition, see below) the term pseudo-synchronous can be extended to periodic processes with completely different periods. The period TN of the process PN is determined by the synchronism with which the process Pn must exchange the input information and output results with the external devices. For a modem, this synchronism is the baud time which is locally generated for the transmitter and determined from the received signal for the receiver.

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Multiple Pseudo-Synchronous Processes Time Multiplexing in a Single Signal Processor

Many realtime applications in signal processing consist of several pseudo- synchronous processes. Pseudo-synchronous processes are processes which must be run periodically, with very slight differences between their periods. A typical example is the transmitter and the receiver of a modem. Under a certain condition (processing time condition, see below) the term pseudo-synchronous can be extended to periodic processes with completely different periods. The period TN of the process PN is determined by the synchronism with which the process Pn must exchange the input information and output results with the external devices. For a modem, this synchronism is the baud time which is locally generated for the transmitter and determined from the received signal for the receiver. In addition, the whole application contains asynchronous programs which are service programs (control, supervisor, diagnostics, etc.) for the whole process. Until now, each process was performed in a different processor. However, present and future signal processors are very fast and can multiplex several pseudo-synchronous processes. The normal way to implement these applications is to use interrupts to perform, on the one hand, the different I/Os and, on the other hand, to call the different process programs, when the input data are ready to be processed. This method not only requires a sophisticated system of interrupt (nesting and priority) but, at each interrupt, requires saving and restoring the entire machine context. As many interrupts are involved in the whole process, this method wastes a great deal of processing power which might be used for more pseudo-synchronous or asynchronous processes. A better method is the following: - Interrupts are only used for I/O operations which are only read/ write register operations...