Development Of The X-ray Pulsar Navigation Detector Timing System Based On MCP

The pulsar navigation shows extreme important signification on stratagem and application of engineering which is the current of spacecraft navigation in future.The X-ray detector which is the core of the X-ray pulsar navigation detects the Xray pulsar photons and gets the exact time of arrival(TOA)of every photon and can supply information of location,velocity,time and position after data processing,realizing navigation independent finally.The precision of TOA which is one of the most important data of the system of navigation will affect the precision of the Xray pulsar navigation.Firstly,this paper introduces several detectors and analyses the advantages and disadvantages of these detectors.Through the analysis,it is concluded that the MCP(Micro-channel Plate)has the advantages of high gain,high sensitivity and fast response time which is suitable for the X-ray pulsar navigation,which can effectively improve the positioning accuracy of pulsar navigation.Then the working principle of the MCP detector is introduced in detail,and the characteristics of the output signal of the MCP detector are analyzed.The signal has small amplitude,very short pulse width,according to the signal,this paper designed a set of high precision timing system,including the amplifier circuit,the filter shaping circuit,the timing circuit,the high stability of clock circuit,the time to digital conversion circuit,and then several implementations for each circuit are analyzed and compared,and choses the optimal way of implementation.Secondly,the hardware design of the timing system is introduced,including circuit principle,technical index,selection of main components and simulation situation.The amplifier circuit amplifies the weak signal for the MCP detector output,then the signal is filtered and shaped which has high signal-to-noise by the one CR different and twice RC integral circuit.The timing circuit adopts the constant timed and the frontier timed circuit,the quasi gaussian pulse signal is converted to a digital logic pulse signal,which solves the time shaking and triggered by mistake.The high stable clock circuit uses GPS to correct the atomic clock,and output the high stability clock which has both of short and long term stability.The time digital conversion circuit uses high stable clock to achieve high precision timing of digital logic pulse.Then,the the software is descripted in detail,and the timing accuracy is improved by the insertion of the FPGA carry.In the end,the test plan is designed and the important components of the timing system and the whole system are tested.The accuracy of the timing system has reached 14.3ns by testing,which can satisfy the need of the X-ray pulsar navigation.