利用线性调频谱法识别与消除单频干扰

Utilizing linear frequency modulation spectrum method to identify and remove single-frequency interference

不等频率采样线性调频变换有三个显著优点:①可以计算单位圆上任意点频率样本,而且起始频率可以任意给定;②频率样本的点数可以与输入数据的点数不相同,可以显著减少计算点;③频率采样间隔可以取值很小,以达到细化频率的目的。这三个优点使得不等频率采样线性调幅调频变换分析方法在消除地震数据单频干扰方面具有明显的优势。常规的时间域压制方法和Chirp-Z变换方法虽然能够压制50Hz工业交流电干扰(单频干扰),但是对于实际海量地震数据,计算效率低,运算费时。线性调频谱分析可以计算数据在一个很窄频带范围内的不等频率采样频谱,通过计算43个线性调频谱样本值,就可以快速确定频率精度为0.001Hz的单频干扰频率,通过54次频率扫描可以确定频率精度为0.0001Hz的单频干扰频率,从而达到消除单频干扰的目的。经理论数据和实际数据处理表明,该方法在压制单频干扰时不会伤害其他频率成分的有效信号,在干扰存在的频率成分上有效信号保存完好,且计算效率大为提高,是目前高覆盖、高密度3D地震数据处理中消除单频干扰的有效手段。

There are 3 advantages for the uneven frequency sampling linear frequency modulation transform method:(1):The frequency sample for arbitrary points in unit circle could be calculated,in addition,the initial frequency could be randomly set up,(2):The number of the frequency samples could be different from the number of the input data,so the calculation points could be dramatically decreased,(3).The frequency sampling rate could be very small so the frequency could be zoomed.The 3 advantages bring obvious superiority in removing single frequency interference.Although the routine time-domain suppression method and the Chrip-Z transform method could suppress 50 Hz industrial interference(single-frequency interference),but for vast amount of seismic data,their efficiency are low and they cost too much time.The linear frequency modulation spectrum analysis method could conduct calculation for the data in a very narrow frequency bandwidth and with uneven frequency sampling spectrum,by calculating 43 linear frequency modulation spectrum samples,the single frequency interference frequency with 0.001Hz frequency precision could be rapidly determined,while by 54 times frequency scanning,the single frequency interference frequency with 0.0001Hz frequency precision could be determined,as a result the single frequency interference could be removed.The processing for theoretical data and field data show that the method suppresses the single frequency interference while it does not harm effective signal with other frequency component,the effective signal could be kept well at the interference frequency,the method could highly raise calculation efficiency,it is an effective method to remove single frequency interference in high fold and high density 3d seismic data processing.