echo characteristic
2.Then the true PGPR echo data (collected by XBX-001 PGPR at Sanxia dam in Dec, 2003) are analyzed by time-frequency methods and STFT algorithm is improved according to the characteristic of PGPR echo signal, and the suitable wavelet is chosen to analyze echo data.
3.The curve from the echo fluid level in rod jumping well is analyzed,the electrocircuit principium of characteristic pulse in the detecting curve is put forward,the method for calculating velocity of sound & fluid level from statistical rule is also introduced.
4.This article introduces the reason, course and characteristic of the new chemicals policy of European Union(REACH) and the echo on it from various fields; and sets forth the opinions and advices.
5.Abstract: The threshold algorithm of the target detection is often used to detect target echo signals.Its performance is based on signals-noise ratio.When signals-noise ratio is great than 6.7,the target can be detected.In order to increase the signals-noise ratio,matching filter is often used.If the system is narrow band system,the noise is color noise and matching filter cannot be used.Therefore,the signals-noise ratio cannot be increased.However,the geometrical characteristic of the laser echo signal is different with the noise.This paper advises the algorithm that detects the target by the geometrical characteristic.When signals-noise ratio is great than 2,this algorithm can detect target.This algorithm has been used in practice.
6.According to the short range detection characteristic and the analytical procedure of the traditional active sonar design theories, the underwater ultrasonic detection theories are studied in depth, including the mathematic models of the ultrasonic channel, emitting wave and echo detection. Furthermore the volume reverberation expression of the underwater ultrasonic detection is deduced, and the CW signal is designed for the emitting wave of the underwater ultrasonic detection system for fuze.
