| With the progress of science and technology,the working mode of left behind and unattended has become the mainstream working mode.With the increasing degree of automation,state Administration of radio and television 725 begins to carry out comprehensive automation.The main problem is the connection and switching between transmitter and antenna system,but the manual inverted antenna operation is adopted.Manual operation brings great disadvantages: slow operation,high risk index(high altitude operation and high voltage operation),high intensity of night shift work,high risk of antenna equipment failure,difficulty of maintenance and management,difficulty of antenna signal sampling and monitoring,etc.At the same time,the system is easily disturbed,no operation,slow speed Low degree of automation,high working environment requirements and other negative factors.With the development of radio and television system,the requirement of broadcast quality is higher and higher,and high quality zero second becomes the necessary task of work.However,in practice,due to various factors,the transmitter can not be broadcast all day without problems.Therefore,in-station and inter-station broadcasting plays an important role,and switching antennas becomes the core of temporary broadcasting.Fast and accurate is the main requirement of acting broadcast,obviously,manual operation appears powerless,automatic,fast,information mode is particularly important.Using advanced antenna switching Turn off the control system,improve the processing speed and accuracy of switch switching,and realize the automation of antenna switch switching.An antenna switch control system for shortwave broadcast base station is developed by combining antenna switch with Rockwell PLC(Programmable Logic Controller).In this paper,the design process of antenna switch control system is discussed,and the working principle of antenna,antenna feeder and antenna switch is introduced.This study completed the design and development of antenna switching switch control system,taking the PLC based on Ethernet/IP technology as the control core,adopting the integrated design concept to develop,and combining with the operation mechanism and control management needs of antenna switching switch,The overall design and development of the control system is completed And the basic components of the system are 1 Ethernet module,1 control module,1 digital input module,1 digital output module and the necessary instrument equipment,such as frequency converter,motor and so on.Meanwhile,the control system selects Control Logix1756 PLC product designed and developed by the Rockwell company,and the data information interaction mechanism is realized by means of the Ethernet/IP system,and the direct and steering state monitoring of the switching switch is realized based on the data interaction.Besides,in order to ensure the convenience of the control system,the touch screen is used as the display of the upper c ontrol computer and the lower control computer,and the writing tool of the upper control instruction is VB,its function is to monitor and control the state and change of the switch;The lower computer control system selects the PLC control device based o n the AB,which will realize the dynamic real-time monitoring of the control switch state and switching operation,and provide the bottom logic operation support for the realization of the control function.At the same time,the remote control function sen ds the switch information to the upper computer and receives the upper computer instruction to control the switch state The auxiliary "local control" function is also used to execute the control instructions entered by the touch screen control terminal,and the lower computer control station is connected to the upper computer monitoring by using the optical fiber Ethernet to realize the decentralized control,centralized management and unified scheduling of the antenna switching switch.Prior to the debugging of the project,according to the accuracy of PLC trapezoidal program in the control of the system,Rockwell PLCRSLogix5000 simulation software is used to simulate and verify the running program.After the project is debugged on the computer,in order to verify the hardware feasibility of the whole antenna switching switch system,according to the standing wave ratio in the short and medium wave transmitter and the antenna feeder impedance matching overview 1.2,the standing wave ratio test should be carried out before the system is put into use.The test results show that the control system shows stable operation Fixed,automatic and efficient,switching switch good and other advantages,can effectively meet the the control function. |
