| 摘要 |
PURPOSE:To attain a communication network with flexibility by conducting code transmission by a frequency modulation system for carrier wave transmission capable of automatic gain control in modulation/demodulation to transmit a signal to a transmission link of the communication network to make the system insusceptible to the condition change of a line. CONSTITUTION:An equation of the operation of a frequency modulation wave (FM wave) expressed in Equation (1) is converted into a sample value form having a sampling interval T by a processing circuit. Then the VCO type control system of the FM wave expressed in Equation (1) is used for the detecting operation at demodulation side, and the detection operation expressed by Equation (3) is attained, where S(t) is a detection signal. Equation (4) representing the response when a transmission data S'(t) is passed through the 1st order filter is obtained by analyzing Equation (3). Then Equation (5) is obtained by representing Equation (3) in the way of the sample value operating equation. That is, a block 56 of COS represents that a table of cosine function is indexed by using an inputted signal as indexing number and an output signal S(nT) goes to an input signal of the block. |
