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为减少声速时差记录误差,对原始声波波形的处理有两种方法,即前沿记录法和峰点记录法。大家知道,历来的声速测井仪都是采用第二峰前沿触发方式来得到时差方波的。这种记录方式有较大的测量误差。如图1所示,“准确时差”是对应两道声信号过零处 A、B 两点的,但由于存在声干扰,要求有一定的鉴别,得到的“实际时差”存在着△_(?)、△_((?)1)的误差。如果鉴别数值相差很大,推算出的误差竟达到记录波视周期的4/1,即25～50微秒/米。
In order to reduce the recording error of the acoustic velocity difference, there are two methods to deal with the original acoustic waveform, that is, the leading edge recording method and the peak point recording method. We all know that the history of sonic velocity logging tools is to use the second peak front-end trigger to get the time difference square wave. This recording method has a larger measurement error. As shown in Fig. 1, “accurate time difference” corresponds to two points A and B at the zero crossings of two acoustic signals. However, due to the existence of acoustic interference, it is required to have some identification. The “actual time difference” ), △ _ ((?) 1) error. If there is a big difference between the discriminant values, the calculated error will actually reach 4/1 of the recording wave period, that is, 25 to 50 microseconds / meter.