The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 08, 1992
Filed:
Aug. 29, 1990
David P Rossum, Aptos, CA (US);
E-mu Systems, Inc., Scotts Valley, CA (US);
Abstract
An improved dynamic digital IIR (Infinite Impulse Response) audio filter and method provides a remedy for the major problems in state of the art digital IIR filtering and dynamic digital filtering for audio. In particular, the required multiplier coefficient size is reduced, such that 16 bit coefficients are adequate for good frequency resolution. In addition, the data size of the multiplier is also reduced, to be similar to the input and output data resolution without inferior noise performance. Furthermore, the structure is easily modified to allow the fixing of the DC (Direct Current) gain of the IIR filter to unity regardless of coefficient choice, eliminating any problems with filter dynamic range at low frequency passbands. Additionally, a dynamic filter structure allows logarithmic filter sweeps and compresses the coefficients further down to as few as 8 bits with adequate resolution for audio throughout the band. The structure allows the alteration of sweep of the filter without excessive computation or the requirement to read the current sweep value.