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:
Jun. 26, 1979
Filed:
Sep. 29, 1977
Shigeru Asakawa, Fujisawa, JP;
Fumio Sugiyama, Yokohama, JP;
Makoto Nakamura, Miura, JP;
Tsukasa Okai, Yokohama, JP;
Tokyo Shibaura Electric Co., Ltd., Kawasaki, JP;
Abstract
In a security communication system, the transmitting unit includes a sample - hold circuit for sampling and holding the original voice signal, an inverting circuit for inverting the polarity of the samples of the voice signal in accordance with a first code, an adder circuit for adding a D.C. signal to the output signal of the inverting circuit, and another inverting circuit for inverting the polarity of the samples of the output signal of the adder circuit in accordance with a second code. The receiving unit includes a sample - hold circuit for sampling and holding the received signal, a synchronizing circuit for extracting a synchronizing signal component from a received signal during, for example a period of non-voice transmission, and for synchronizing the transmitting unit with the receiving unit, an inverting circuit for inverting the polarity of the samples of the received signal in accordance with the second code, a circuit for removing a D.C. signal component from the output of the inverting circuit, and a polarity inverting circuit for restoring the received signal from which the D.C. signal has been removed by said removing circuit to the original voice signal through the polarity inversion of the received signal in accordance with a third code.