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The muzzle velocity of the projectile is one of the important parameters for flight control of the projectile. In order to further improve. The stability and precision of the measurement of the muzzle velocity of the projectile, the relative theory of velocity measurement was studied and a new experimental method was put forward. Analysis shows that timers starts or stops timing at the zero point of the voltage signal can improve the velocity measurement accuracy. In order to solve the problem, a signal processing module was designed. The signal processing module can convert the induced voltage signal into a square wave signal. Then the DSP(Digital Signal Processor) can capture the falling edge of the square wave signal and generate interrupt timing. Thus, the timer can be accurately timed at the zero point of the induced voltage signal. In addition, the relevant theories and analysis methods of velocity measurement were established in the article. The induced voltage distribution on the axis of the excitation coil was modeled and simulated. The velocity measurement experiments are carried out by using the proposed method and the traditional pulse induction method. The comparison of experimental results shows that the test method used in this paper has a higher measurement accuracy and the relative error can be controlled within 1%. In this paper, there are some innovations in the theory of speed measurement and the experimental method of timer timing at zero induced voltage. The measurement method is of great significance in the field of velocity measurement. [ABSTRACT FROM AUTHOR]

The two kinds of polymer-derived SiAlCN ceramics resonant cavity wireless passive temperature sensors with and without patch antenna were designed. Their maximum wireless detection distances were obtained through simulation and calculation. Through the simulation of reflection and re-radiation characteristics of the two kinds of sensors, the mechanism of the integrated patch antenna on increasing the detection distance of the sensors were revealed. The sensors were fabricated and measured to verify the method. The results show that, compared with the sensor without the patch antenna, the maximum detection distance of the sensor with patch antenna was increased from 18 mm to 32 mm. And integrated patch antenna has almost no effect on the characteristics of the sensor’s resonant frequency change with temperature. It demonstrates that the method of integrating patch antenna is an effective way to increase the wireless detection distance of the resonant cavity wireless passive sensor. [ABSTRACT FROM AUTHOR]

Ensuring the synchronization of backscattered Raman light and improving the sampling rate are of great importance to improve the spatial resolution of a distributed Raman temperature measurement system. To keep the synchronization of the Anti-Stokes and Stokes light and improve the sampling rate, four effective methods are proposed in this paper. First, the asynchrony caused by the difference in the hardware is eliminated by attaching a fiber to the pigtail of APD, which detects the earlier arriving signal. Next, the data acquisition card chooses different sampling rates for the Anti-Stokes and Stokes light according to the velocity of propagation. Then, a new algorithm is adopted to decrease the difference in the fiber position between the Anti-Stokes and Stokes signals. Finally, the optical switch with different length of pigtails is applied to improve the sampling rate without upgrading the hardware of data acquisition card. By theoretical analysis and experimental simulation, the proposed measures in this paper can improve the spatial resolution effectively. [ABSTRACT FROM PUBLISHER]