Patent ID: 7039360
Filing Date: 2006-05-02
Classification: H03H,H04B,H04N

Abstract:
1. An external noise intrusion prevention device having input and output terminals adapted to be connected to a coaxial cable, the external noise intrusion prevention device comprising: a first filter circuit that passes a signal in a first predetermined frequency band and connects the input terminal and the output terminal to each other; a second filter circuit that passes a signal in a second predetermined frequency band that is different from the first predetermined frequency band; and a noise elimination circuit connected between the input terminal and the output terminal through the second filter circuit, wherein the noise elimination circuit is formed by cascading a front connection transformer and a rear connection transformer, each having a primary winding and a secondary winding, wherein one end of the primary winding of the front connection transformer is connected to a core on the input terminal side and the other end of the primary winding of the front connection transformer is connected to an input-side ground section, and wherein one end of the secondary winding of the rear connection transformer is connected to a core on the output terminal side and the other end of the secondary winding of the rear connection transformer is connected to an output-side ground section.