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:
Oct. 01, 1996
Filed:
Dec. 12, 1994
David L Hershberger, Nevada City, CA (US);
Tektronix, Inc., Wilsonville, OR (US);
Abstract
An improved scrambler for serial digital video that is compatible with SMPTE Standard 259M inserts a detector/dithering circuit between the input serial digital signal and a scrambler. The scrambler's statistics are observed by a pair of up/down counters. One counter monitors the scrambled data prior to NRZI encoding to determine transition density, and the other monitors the NRZI encoder output to determine the relative density of 'ones' and 'zeros' in the scrambled output signal. A pseudorandom generator generates a dither signal which is combined with the least significant bit of selected video words of the input serial digital signal when enabled by the terminal count output from either counter. A complementary descrambler has a similar detector/dithering circuit at its output to restore the original least significant bit of the selected video words. The improved scrambler/descrambler may be implemented in either the serial or the parallel domain. Thus pathological signals are avoided that could create problems within the serial digital video bit stream.