| 摘要 |
PURPOSE:To simplify the circuitry, by setting an emission timing to emit an ultrasonic wave forward and backward alternately to make a section of processing forward and backward received signals in common. CONSTITUTION:An ultrasonic beam is emitted forward and backward slantly from ship and reflected waves from water masses at a position away from a ship bottom are received to measure a ship velocity after detecting a Doppler shift. An original oscillating section 26 sets an emission timing so that ultrasonic waves are emitted forward and backward alternately. A received signal processing means comprising a receiving section 18, a frequency detecting section 56, an arithmetic section 58 and a ship speed display section 60 is provided in common both for forward and backward directions and detects a Doppler shift from received signals as reflected wave to measure the ship velocity. A forward-backward switching section 28 connects the signals individually received from front and back to the received signal processing means synchronizing the emission timing.
|
