Browse Prior Art Database

Overflow and Saturation Control In Signal Processor

IP.com Disclosure Number: IPCOM000049013D
Original Publication Date: 1982-Apr-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Belloc, J: AUTHOR

Abstract

Most signal processing functions involve filtering functions which are implemented as fixed numbers of product accumulation. These operations may overflow accumulator capacity, and therefore this overflow occurrence should be detected and the accumulator contents should be adjusted through a saturation operation.

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Overflow and Saturation Control In Signal Processor

Most signal processing functions involve filtering functions which are implemented as fixed numbers of product accumulation. These operations may overflow accumulator capacity, and therefore this overflow occurrence should be detected and the accumulator contents should be adjusted through a saturation operation.

Taking into consideration twos complement number properties (twos complement arithmetic may be represented as a cyclic closed set), a method is proposed for performing the overflow saturation operations in signal processors. In effect, when dealing with twos complement numbers, no attention should be paid to overflow, provided the final result is in the proper range of values without overflow; thus, one need only saturate the final result if it is still overflowing.

Overflow detection may be based on sign bit consideration. A 6 dB dynamic range protection may be achieved by letting the leftmost bit position of the accumulator be used as a sign position extension and one bit of the numbers to be accumulated be Q sign extension bit. Overflow is detected at any desired accumulation stage by testing that the sign bit is not the same as its own extension on the accumulation result. This operation can be performed using a simple XORing operation. Saturation operation is then performed on the final result only. The proposed process therefore enables overflow and saturation control with a signal processor perfo...