The Design And Implementation Of Hydrophone Electrical Signal Simulator

Hydrophone as the key device of the sonar equipment can receive underwater ultrasound signal which is mainly used for locating, ranging and navigation of ships. When people are acquiring signals, they must go into the cabin or special hydrophone experimental ponds for the reason that the hydrophone is usually installed at the bottom of ships which make the experiment inconvenient and also required a huge cost. Since the hydrophone output signal, which is in micro-volts level, is very weak, the conventional signal generator can’t simulate the week sensor signals even if it is versatile. With the growing demand for ocean development, more and more applications is designed for hydrophone. Therefore, the demand for the simulation devices of hydrophone electrical signal is extremely urgent.The research contents in this paper include the signal generation, noise filtering, low noise signal attenuation and signal acquisition. Signal generation includes direct frequency synthesis and amplitude control. This paper analyzes the entire frequency synthesis process and each node of the signal spectrum in term of frequency synthesis. Amplitude control uses d/a converter to simulate the function of the digital potentiometer and complete sine wave and triangle wave modulation through the numerical approximation method. Due to the d/a converter quantization error after the amplitude modulation, the output signal contains high order spurious signals. In order to make the modulated waveform more smooth and signal-to-noise ratio much higher, we study and design fourth-order Butterworth filter. This paper mainly analyze flatness filter and phase characteristic. Signal attenuation network mainly complete the attenuation of volt level signals to the micro-volt level. The paper mainly studied the Resistance-capacitance attenuation network in the passband flatness, the influence of thermal noise, and the influence of temperature. For feedback signal acquisition part, in order to acquire more accurately output signal and reduce the cost of software, the paper studied and implement RMS technology for signal from the hardware side, so that all output signals can RMS.In this paper we completed the analog device design of the electrical of hydrophone by rational circuit design and software control, and the results achieved the expected results. This device greatly simplifies the experimental conditions of hydrophone related experiments, and saves the experiment cost. It is also provide a variety of weak signal source for other sensor signal applications. The device can simulate some typical communication signals of hydrophone which contain rule sinusoidal, sinusoidal signals which are amplitude modulated by sinusoidal or triangular wave signal and frequency modulated sinusoidal signal. The output signal amplitude and the hydrophone signal are in the one level which is between 50 and 300 micro-volts.