| 摘要 |
PURPOSE:To freely set the characteristic of transmitting waves so as to reduce the side lobe in the frequency characteristic of the transmitting waves by calculating the time pulse waveform of the transmitting waves after setting the frequency characteristic of the waves by using a weighted function. CONSTITUTION:Before calculating a time pulse waveform meeting the conditions of a designated center frequency FC, frequency band width BW, and pulse time TW, a frequency characteristic calculating section 11 calculates the frequency characteristic of transmitting waves by using a prescribed weighted function and shapes the frequency characteristic to a waveform to a smooth round curve on both sides of the center frequency FC. When the auto-correlation function of a frequency-modulated pulse signal is found by calculating 15 a time waveform from the frequency characteristic and A/D-converting 17 the time waveform, the side lobe becomes smaller. At a receiver, in addition, the correlation between part of a transmitting waveform or received waveform stored 22 as a reference time waveform and received waves is calculated 23. At the time of performing the calculation 23, the side lobe of the cross-correlation is also regarded as small. Therefore, transmitting waves which are excellent in distance resolution and can withstand against noise can be obtained. |
