A novel miniaturized autonomous digital depth sounder MADDS" was developed for automatic storing and recording of sea bottom depth, along with communication to various marine equipment, like chart plotter, GPS and radar, using NMEA 01 S3 protocol. The analog part of the sounder consists of the miniature HEXFET transmitter and the one chip double opamp receiver. The digital part constitutes the PIC microcontroller, with a built-in analog-to-digital converter (ADC) and universal asynchronous transmitter (UART). Such architecture allows sampling and storing the echo in compressed form in PIC's RAM memory. The UART allows transmission of the data acquired by the sounder between successive pings, via the serial line. The dedicated software of the sounder consists of two parts: one hard-coded in the microcontroller EEPROM memory and the other running on attached equipment. The first one uses unique features of the microcontroller, which allows real-time compression of acquired echo data, implementation of bottom tracking algorithms and communication with host computer. The second one in general is used for presentation of echo signals and displaying of various echogram graphics along with associate reports. The sounder design past successfully extensive field tests on Wdzydze Lake, and is now under commercialization in C-MAP Group in Italy.
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