WIDE-BAND RADIO TRANSMISSION SYSTEM FOR BOTH ANALOG AND DIGITAL APPLICATION

摘要

PURPOSE:To form an economical microcircuit, by using an analog system and a digital system to transmit a TV signal and other signals respectively. CONSTITUTION:An FM modulator 1 modulates the frequency of an IF signal of 70MHz with an input of a TV signal. A PSK modulator 2 modulates the phase of said IF signal with a PCM multiplex telephone signal. The modulated IF signal is mixed with the output of a local oscillator 52 through an up-converter 51 of a transmitter 5, and the frequency of the IF signal is converted into a microwave band. Then the IF signal is amplified by an amplifier 53 and radiated through an antenna system 6. This radiated IF signal is amplified by a receiver 8 through a receiving system 7 of the remote side station and then converted again into original IF. The transmitter 5 contains a limiter amplifier 54 and a linear amplifir 55 and is switched by switches 56 and 57. The transmitting and receiving end offices have switches 9 and 10 respectively. It is possible to transmit the TV signal by switching the switch toward a contact (a) and then the PCM signal by switching the switch toward a contact (b) respectively.