| 摘要 |
PURPOSE:To obtain a reflection signal having necessary width, and containing exact Doppler displacement irrespective of the depth of water, by controlling the transmitting pulse width in proportion to the depth of water. CONSTITUTION:When transmitting, a voltage variable monostable circuit 2 is operated by a transmission trigger generated in a control part 1. In this case, to a control terminal of this monostable circuit 2, voltage proportional to the depth of water is applied, therefore, an output of this monostable circuit 2 obtains a signal having pulse width proportional to the depth of water. By the trailing edge of this pulse signal, a monostable circuit 3 is operated, this output and the output of the monostable circuit 2 are inputted to an OR gate 4, and in accordance with its output, a transmitting part 5 emits a pulse-like ultrasonic signal having pulse width proportional to the depth of water to the sea bottom from a transmitter and receiver 7 through a transmission and reception switch 6. A reflected signal is processed by the transmitter and receiver 7, the transmission and reception switch 6, a receiving part 8, a comparator 9, an integrator 9, a frequency tracking circuit 15, etc., and Doppler displacement in the center part of the reflected signal is detected. |
