| 摘要 |
<p>PURPOSE: To make hardware of transmission and reception equipments simple and efficient by using a frequency modulation technique to perform signal modulation and spectrum expansion in a CDMA(code division multiplex access) cellular radio transmission system. CONSTITUTION: A narrow-band information signal to be transmitted is inputted from an input 201 to a modulator and a spectrum expansion transmitter 203. In the transmitter 203, the narrow-band signal is converted to a wide-band signal for radio transmission by an antenna 205. This wide-band signal is received by an antenna 207 and is sent to a demodulator and a spectrum inverse expansion receiver 209. The receiver 209 copies an expansion code added to the information signal before transmission and inversely expands and demodulates the reception signal based on this code and extracts the transmitted original narrow-band signal to output it to a lead line 211. Thus, hardware for transmission and reception equipment is simplified so as to make a system efficient.</p> |
