Abstract: A technique of achieving optimal noise suppression with respect to a video signal whose noise amount differs according to brightness is disclosed, and according to the technique, a low-luminance detecting section 18 detects a video signal of a relatively low luminance, a suppression amount setting section 19 generates a noise suppression amount which becomes larger as the luminance of the video signal becomes lower, and a noise suppressing circuit 17 suppresses noise with the noise suppression amount generated by the suppression amount setting section with respect to the video signal of a relatively low luminance detected by the low-luminance detecting section.

Abstract: A wireless communication network system includes a communication controller, and a plurality of terminal devices which can communicate with the communication controller by wireless. The communication controller includes a first section for detecting absence of a received signal from any of the terminal devices, and a second section responsive to an output signal of the first section for periodically generating a nonbusy signal, which can be discriminated from another signal transmitted from the communication controller, in the absence of the received signal. Each of the terminal devices includes a third section for detecting the nonbusy signal, and a fourth section responsive to an output signal of the third section for permitting transmission from the terminal device after the nonbusy signal is received by the third section.