| 摘要 |
PROBLEM TO BE SOLVED: To provide an N-wave demodulator incorporating a high frequency modem having not only a demodulation function of received data but also a data modulation function capable of modulating control data and transmitting the modulated data to a monitor camera. SOLUTION: When a remote controller 38 selects a channel for a monitor image, an MPU 41 controls a PLL circuit 101 to set a reception channel of a tuner 102. The tuner 102 selects the channel of the monitor image received from high frequency switches 51a to 51d and converts the signal of image into an intermediate frequency signal. A video detection circuit 103 applies video detection to the intermediate frequency signal to extract a video signal, composes and amplifies character data from a character data generator 104 and outputs the composed data to a 4-image composite unit from an output terminal 106. Further, when the remote controller 38 applies control operations to the monitor camera, the MPU 41 receives the permission of a management CPU via a control CPU 31, sets a transmission frequency of a variable high frequency modem 43 according to an instruction from the management CPU and transmits a camera control signal. COPYRIGHT: (C)2003,JPO
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