Design Of Multi-point Displacement Time-division Telemetry Transmitter

Due to the influence of natural environment,or because of too long operation time,large buildings will have slight displacement in some locations.The amount of micro displacement that different materials can bear is different.When the displacement exceeds the scope of the material itself,there will be a safety accident,such as the collapse of the bridge pavement,the fracture of the building floor,the landslides and so on.Therefore,monitoring the location of large buildings with possible micro displacement is a necessary measure to prevent accidents.In this paper,a time-division telemetry transmitter can be used to measure the micro displacement of the mountain or high buildings,so as to prevent the occurrence of the accident.In the micro displacement measurement system based on code division multiple access(CDMA)and frequency division multiple access(frequency division multiple access),the reference point is a transmitter and a transmitting antenna at the reference point.At each observation point,a transmitter corresponds to a transmitting antenna.This will make the whole system cost more expensive and not easy to carry.Based on this,this paper presents a way of time-division telemetry,which requires only two transmitter: one transmitter as a reference transmitter,a transmitting antenna and a transmitter as an observation transmitter.Pass the switch to control the logic signal to transmit the transmitter signal to the transmit antenna.The use of time-division telemetry can greatly simplify the volume of system equipment and reduce costs.In the micro displacement measurement system,the phase error caused by the signal is mainly due to the dithering of the antenna and the temperature drift of the channel.In this paper,a method of measuring the phase error is proposed.By using the transmitter with 2×2 channels,the reference point signal and the observation point signal are controlled by microwave.The system switch is mixed with the reference point signal,and is coupled to the receiver channel of the transmitter by the power synthesizer,and the carrier phase difference is calculated by the down conversion to the baseband.Secondly,this paper introduces the development platform of the time-division telemetry transmitter.The development platform mainly adopts the AD9361 RF chip of ADI company.The high programmable performance and broadband capability of the device make it the first choice of transmitter.In addition,the development platform is also equipped with the motherboard of ARM+FPGA,which makes the working mode configuration and baseband signal processing faster and more efficient.Finally,the realization of the beacon of time shared telemetry radar is introduced emphatically.The matching motherboard FPGA module is used to generate PN code signals,and IP is used to check the PN code signal with dual data rate,and the radio frequency carrier signal is modulated.The data interface is transmitted to the AD9361,and then ARM is used to configure the parameters of the transmission channel of the AD9361.The data interface is configured into double duplex duplex mode to enable the signal to be sent out.The power combiner is used for spontaneous self collection in the receiving channel.In FPGA,the phase variation of the carrier signal is obtained by integral accumulation,and the phase difference of the two transmission channels is calculated,thus the phase error of the channel is corrected.