| As the further development of electronic technology and information technology, remote control technology has also made considerable progress. In the background of the country to develop blue-water navy, in the hydrological sciences, water-sound remote control system has been studied and achieved fruitful results, making underwater acoustic remote control system has been widely used. This article will explore the acoustic remote control technology using in underwater sampling. In the underwater remote-controlled process, although the amount of communication signals is small, the information still needs to pass through the underwater acoustic channel .Because of the complexity of underwater acoustic channel, measuring device placed underwater, there is reflection, refraction, scattering, multi-path interference, Doppler effect, and water, noise and other effects to remote-control signals, reducing the receiver signal to noise ratio.The system's reliability for the remote control system is essential,so we must take effective measures to anti-attenuation and interference , improving signal to noise ratio.In order to solve the difficulties encountered by underwater remote control, the pseudo-code modulation technology have been introduced into the field of underwater remote control. Pseudo-code modulation technique is the technique which the information signal and the pseudo-code waveform multiplied to modulate the signal, it has conspicuous advantages of anti-jamming, anti-fading and anti-multipath, as well as confidentiality and other aspects, it is a effective technology anti-multipath communication at low noise ratio ,with good hidden nature and low probability of intercept performance, which make it paid more and more attention in the underwater acoustic remote control system.Ultrasonic remote control is one of the developing relatively fast in all of remote control methods. Ultrasonic has a good pointing, the attenuation in water is small, beam radio feature fine.The signal modulated by pseudo-code, transmitted and received by ultrasonic , can effectively resolve the large loss of energy ,multi-path interference, Doppler effect and so on,which other remote control methods encountered used underwater , while a higher accuracy of the remote control.This paper's main task is to demonstrate and complete the underwater ultrasonic remote control system and receiving device of multi-position sampler of the underwater part of remote control system, as well as to implement hardware and software components of the design. Understandding the research background of the premise, the paper introduces the details of the remote control technology and the basics of ultrasonic technology,identifies the remote control device hardware solutions, introduces the ultrasonic transducer of the main technical indicators, as well as dedicates circuits of the ultrasonic remote control. Using pseudo-code modulation to give the signal spread spectrum modulation, comparing the existing pseudo-code modulation sequences, in the course of underwater remote control with fewer devices, choosing m-sequences with good performance from the relevant as the final choice of pseudo-code modulation sequence .Based on ultrasonic and pseudo-code modulation techniques,determining the underwater ultrasonic remote control hardware programs, micro-controller uses the low-power At89S52 of 51 series microcontroller, ultrasonic transceiver uses LM1812 specific integrated circuit, using m-sequence to give the remote control command signals pseudo-code modulation implementted through hardware circuit, using the LM1812 to receive and spread spectrum in the water, demodulating the signal, finally getting the command signal,then sending to the implementing agencies to issue multi-position sampler's behavior. This article mainly achieves the foregoing functions, finally completes software framework of the underwater ultrasonic remote control circuit , debugs it. |
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