The Research And Development Of New Acoustic Signaling System

The research on acoustic properties of sediments focuses on both the acoustic velocity and sound attenuation. Currently, the major domestic has adopted direct laboratory measurement method to measure the acoustic properties of sediments. But different sediments require different performance of measurement system equipments, so, in order to acquire accurate acoustic property, both adjustable signal waveform parameters and sweeping at different frequencies are needed. Existing ultrasound measurement apparatus mainly adopt the instruments used to measure the building structural defects, but the output signal parameters are not adjustable based on measurement requirement, and sweep signal can’t be exported. Obviously, existing ultrasound measurement is difficult to meet the requirements which contain adjustable waveform parameters and sweeping at different frequencies, therefore, it is essential to develop new acoustic measuring instrument. The acoustic signal source is the important part of the measurement equipment, which can provide to drive the transducer voltage. Therefore, to meet the measurement requirements of seafloor sediments acoustic characteristics, this thesis mainly studies the development of new acoustic signal system.In order to meet the requirements of seafloor sediment laboratory measurements, and according to our previous research work of the actual needs, based on the analysis of the ultrasonic transducer characteristics, combining the advantages of frequency synthesizer and microcontroller technology, designed a special acoustic properties of the seabed sediment laboratory measurement signal system.The system mainly consisted of two parts, hardware and software. Hardware section selected DDS chip AD9850as the system core of acoustic signals, the AT89S52as the controlling chip, the hardware implementation were given in detail, included acoustic signal generation module, the waveform counting module, the transducer drive module, the temperature detection module and a signal receiver module, and explained the considerations of system PCB design. The software included AD9850frequency control part program,82C54wave number of the control program, the temperature detection procedure. CPLD data acquisition card clock frequency control procedures. Since the system has wanted use with CPLD acquisition card, the entire system control commands sent from the host computer, then signaling system performs the appropriate actions, signaling system and CPLD data acquisition card communication program is the key part of the software. Thesis presented in detail controlling flows and timing diagrams of each functional module of the program.Finally, the thesis has verified the stability of system output sinusoidal signal and the pulse signal by the time-domain analysis, and using spectrum analysis techniques to study the output signal of the signal receiving module, the frequency characteristics of the transducer and receives performance of signal receiving module have been verified. Experimental results show that the signal system function was stable and reliable, the parameters of signal receiving circuit design are reasonable, met the design requirements.The output signal of acoustic signal system have some advantages, included bandwidth frequency, controllable signal frequency and wave number, high frequency resolution, fast conversion speed, can sweep measurement. Simultaneously, the duty cycle of the signal and the output voltage is adjustable, flexible using, application is wide.