ABSTRACT
In the new century, the human comprehensively understand, develop, use and protect the sea. With it comes, who can grasp the sea area, who would be in the initiative position in the future development. To become the sea powerful nation have to have the ability to grasp the advanced sea technology. The sonar technology is one of the most basic and important technology undoubtedly in the sea exploration and development. Because the underwater operating systems such as the machine drilling shallow stratum core sample in deep sea, the video grab bucket and so on are small and agility, they are capable of exploring and operating in smaller bodies of water in addition to areas of the ocean that would be out of reach for a larger vehicle. Being autonomous requires that the system must be capable of performing without the need for human supervision, so use of external sensors such as sonar are needed to ensure the safety of the vehicle during missions. However, since all of the onboard instrumentation and external equipment must also be miniature in size, the implementation of a small sonar system is desirable.
In view of urgency of the sonar altimeter ,this paper analyzes the domestic and foreign sonar altimeter system research situation and developing tendency, then introduce briefly the basic characteristics of sonar and the theory of measuring distance.It also compares the microcontroller often used in the sonar altimeter system based on completing the tash and satisfying the sonar altimeter system’s characteristic, at last, we takes the embedded microcontroller PIC16C74 of MICROCHIOP Corporation as the core IC. It formulates the system design plan according to the system’s function request, including the hardware and software design.
The hardware uses PIC16C74MCU which completes the signal transmitting, the data judging and the data processing as well as controls the Flash memory and the basic communication. The paper introduce the control circuit of sonar signal transmitting, the analogue circuit of echo signal, the expansion circuit of the memory and the communicate circuit to the compute. The memory uses the Flash from ATMEL Corporation, the communicate circuit via Multichannel RS-232 Drivers/Receivers to connect with the compute.In addition, the transducer uses PZT-4 46kHz piezoelectrical tile to achieve conversion between acoustic energy and electrical energy.
The softwaere design uses the modular design method, and divides into the signal transmitting module, the data gathering module,the timing module, the memory controlling module and the communicating module.
Finally, this paper introduces debugging of each part and the whole, including the performance test of piezoelectrical tile, every functions module debugging and the procedure debugging on line. Then, it summarizes the whole work, points out the work achievement and the significance, and forecastes the next further work.
The sonar altimeter is also broadly used in the ocean, and has the broad market prospect.
Keywords：deep-water, miniature , the sonar altimeter ,signal processing
