Design Of High-speed Data Acquisition System For Ionosonde

The data acquisition of ionosonde is the basis for ionogram determination and ionospheric parameter extraction.From the ionogram determination information,the ionospheric electron concentration profile,true height and other characteristic information can be reversed,the key is to obtain a higher-quality ionogram,which places higher requirements on the performance of the data acquisition system of the ionosonde.In order to realize the high speed,high accuracy,high stability,high sensitivity,high signal-to-noise ratio and other performance of the ionosonde data acquisition system,this paper designs the ionosonde data acquisition software and hardware module with a PCI Express bus interface with IP hard core solution.Using FPGA as the system control core,16-bit high-performance analog-to-digital converter ADC as the acquisition chip,and the independently designed ICSA bus as the data transmission channel to implement the ionosonde acquisition system platform,while using Win Driver under the WDM driver framework combined with the Visual C ++ platform,the acquisition system driver program and the application software design of the host computer were implemented.The system was applied to the ionosonde and overall debugging,and a long-term trial operation was conducted at the field observation station to obtain a large number of ionogram.Observed data,compared with the ionogram of the original ISA bus,and analyzed the original data,obtained innovative preliminary observational research results.First,according to the requirements of the digital ionosonde(PDI-2)data acquisition system,the PCI Express bus was chosen to be applied to the ionosonde acquisition system through different bus introductions.According to the overall plan of the acquisition system,the design of the hardware module is completed using modularization and scalability.The hardware module is mainly composed of FPGA(EP4CGX150CF23C8N)main controller and peripheral configuration circuit,16-bit high-speed analog-to-digital converter ADC(LTC2192)circuit,PCIE interface circuit,SRAM logic design,custom ICSA bus driver circuit,etc.This hardware module configures the task of the FPGA through EPCS4SI8 N.The ADC module completes the acquisition and quantization of the ionospheric echo signal and transmits it to the host computer through the differential signal line and the FPGA.According to the layout and routing guidelines,the circuit is required to complete the six layers of the PCB for the differential signal line board design.Secondly,the software module of the ionosonde acquisition system is designed.The software module is divided into driver program design and upper computer datadisplay.In terms of driver design,this paper uses the Win Driver software and Visual C ++ platform to generate the driver of the system.In the application part,according to the data display and storage requirements,the visual c + + platform is used to write relevant functions to complete the data visual display.The ionogram collected by the ionosonde is saved in the format of DIF / ODF,so as to facilitate the offline study of the ionosphere.Finally,the system was applied to the overall debugging of the digital ionosonde(PDI-2)platform,and a large amount of observation data was obtained,and preliminary research results were obtained.The overall debugging includes the communication between the system and the driver.The relevant interface modules are written through Verilog HDL and the continuous reading and writing speed of the DMA is tested.The data comparison and analysis are performed at field observation stations in Wuhan,Beijing,and Hainan to obtain observation data.By comparing the results with the original ISA bus system,it can be seen that the system has improved the data transmission rate,the completeness and clarity of the ionogram,the system performance is stable and reliable.In the data analysis part,the obtained raw data without digital signal processing is combined with MATLAB to show the amplitude changes of the O and X waves in the echo signal,and the change of the Doppler frequency shift in Sanya area for one day is given.The ionosonde high-speed acquisition system designed in this paper uses FPGA,16-bit high-performance ADC,PCIE bus and custom ICSA bus to apply to the system.Compared with the original ISA bus system,the acquisition system has improved accuracy and transmission speed.The acquired of ionogram O wave and X wave trajectory are more clear and complete.The obtained Doppler frequency shift can be used to study the ionospheric irregular body happened.The system runs stably and meets the performance requirements of the ionosonde acquisition system.