| 摘要 |
PURPOSE:To offer versatile information by applying spread spectrum modulation to information singly or compositely and sending the result in a frequency band of an idle channel of a television broadcast. CONSTITUTION:A digitized signal Di is fed to an input terminal 1 and frequency spread spectrum modulation to the signal Di by a frequency spread spectrum modulator 2 so as to expand the frequency spectrum to a band within 6MHz. The modulation signal is fed to a transmitter 3 and sent as a radio wave 7 of the television frequency band. When the channel number N is an idle channel of the television of the district, either VHF band or UHF band is used. The tuner 4 is set to the N-th channel at the reception side to receive the radio wave 7, the reception signal is demodulated by the frequency spread spectrum demodulator 5 and the signal Di is obtained at an output terminal 6. Thus, versatile service is offered. |
