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:
Apr. 16, 1991
Filed:
Jun. 26, 1989
Yoshihiro Yamamura, Tokyo, JP;
Takashi Ogihara, Tokyo, JP;
Yoshinobu Nakanishi, Tokyo, JP;
Tomohiro Nishizono, Tokyo, JP;
NEC Corporation, , US;
Abstract
In a scrambled-communication system, a transmitting station generates a scrambling noise having a periodically-recurrent series of noise patterns and scrambles an information signal by simply summing the scrambling noise to the information signal, whereby the information signal is totally unintelligible by an interceptor. At a receiving station, a noise-cancelling signal is generated by an adaptive transversal filter and supplied to a subtractor where it is combined with the scrambled signal to recover the information signal. For generating the noise-cancelling signal, a descrambling noise identical to the scrambling noise is generated. The filter has a tapped-delay line for receiving the descrambling noise and a plurality of variable tap weights connected respectively to taps of the tapped-delay line. The outputs of the tap weights are summed to produce the noise-cancelling signal which corresponds to the scrambling noise if the tap weights are adjusted to optimum tap coefficients that are derived from the descrambling noise and from the output of the subtractor. The repetition frequency and noise pattern are the key for descrambling the scrambled signal.