| 摘要 |
<p>PURPOSE:To enable an accurate measurement of distance to an object by transmitting an FM modulated wave prior to the timing of the zero reference. CONSTITUTION:A sweep range signal S of a recorder 1 and a set pulse width signal W of a signal processor 2 are inputted as address data of an ROM5 and a specified data is inputted into a presetting data terminal of a counter 4 with a preset. When the output data of the ROM5 is preset for the counter 4 with a preset by a zero reference pulse T1, the counter 4 subtracts the preset data on a clock signal T2 and generates a carrier T3 when reaching zero. By this signal, the signal processor 2 generates an FM modulated wave with a set pulse width TP, which is converted into an acoustic signal with a receiver/transmitter 3 to be emitted into the water. On the other hand, the reflected signal (received signal R) from the water is converted into an electrical signal with the receiver/transmitter 3, undergoes a correlation processing with a memory having a transmission signal with the signal processor 2 and the received signal RX correlation processed is recorded on a recorder 1 as received signal. Thus, the generation of the FM modulated waves for the time corresponding to a transmission pulse width rather than the zero reference pulse of the recorder allows the reading from the zero reference position to correspond to an object when the distance is read out on a recording paper.</p> |
