| 摘要 |
PURPOSE:To provide a compact and light modulator and demodulator for a spectrum diffusion communication at a low cost by which a low speed transmission can be attained. CONSTITUTION:In a spectrum diffusion modulator, the sampling of an analog signal is operated, an obtained sampled value is quantized, a carrier frequency to be assigned to each chip of a PN signal 8 is specified corresponding to the quantization level, a carrier is distributed according to the specification, and the 2 phase modulation of the cart is operated based on the PN code of each chip. That is, (A) a frequency (f)1 is assigned to the entire chips in order to cope with the maximum value of the analog signal, (C) a frequency (f)2 is assigned to the entire chips in order cope with the minimum value, and (B) the same number of frequency (f)1 and (f)2 is assigned in order to cope with an intermediate value. In a demodulator, each spectrum diffusion modulation signal is allowed to pass through a correlator whose central frequency is (f)1 and (f)2, detected by a detector, and the sum and difference of the outputs are searched, and the amplitude value of a difference signal is detected by using a sum signal as a synchronizing signal, so that the data can be modulated. |
