Circuit Design And Implementation Of AM Broadcast Signal Parameter Measurement

As a way of information transmission,the importance of broadcasting in information dissemination is self-evident.It must not only promote the party's line and policy,but also reflect the lives of people.Broadcast monitoring is the guarantee of broadcasting safety,and the measurement of the parameters of the transmitting signal is an important part of the broadcast monitoring task.According to the requirements of broadcasting work,the quality of signals transmitted by the transmitting station needs real-time monitoring,so as to provide counting guarantee for the safe transmission of broadcasting signal.Signal intensity,frequency deviation and amplitude modulation are important parameters reflecting the quality of AM broadcast signals,and they need key treatment in the broadcast monitoring.In this paper,the measurement methods of the above three important parameters in the broadcast signal are studied.According to the measurement methods,the measurement system is designed,debugged,and tested,and finally the measurement of the parameters is finally realized.We systematically study the overall structure and design ideas of parameter measurement to solve the problems in the measurement of broadcast signal parameters.According to the principles of each parameter measurement,we design the measuring method and hardware circuit of each parameter.Based on the relationship between the control voltage of the automatic gain of the intermediate frequency amplifier circuit and the received signal intensity,we have the signal strength measurement circuit.In order to meet the accuracy requirements of the carrier frequency measurement,an improved scheme is proposed in circuit design and implementation.and phase-locked loop is introduced as the key link of carrier frequency deviation measurement.For the problem that the large-scale amplitude measurement is not accurate enough,based on the method of peak value measurement,high-precision amplitude measurement is proposed,and its principle is theoretically analyzed and applied to the actual circuit.In terms of software design and implementation,to make the frequency measurement more accurate,we use the combination of direct frequency measurement and indirect frequency measurement to achieve frequency measurement.Aiming at the problem that serial port multi-machine communication affects the normal counting of the lower computer,a response mechanism is proposed to initialize counters after communication.Finally,this thesis systematically illustrates the welding and debugging process of the measurement system circuit.The signal intensity measurement system,the frequency deviation measurement system and the amplitude modulation measurement system are tested respectively.The data analysis shows that the performance index of the designed broadcast signal parameter measurement system can meet the measurement needs.The parameter measurement system developed successfully runs in the broadcasting transmitter,completes the real-time monitoring of AM broadcasting signal,and obtains monitoring data.