How to change values in a time trace A-scan to zero

1 次查看（过去 30 天）

显示更早的评论

Alan Keenan 2020-11-30

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/669773-how-to-change-values-in-a-time-trace-a-scan-to-zero

评论： Mathieu NOE 2020-12-2

I have an array of 1600 rows x 1000 columns

Each row is an A-scan time trace of ultrasonic data

The A scans look like:

Note the difference in arrival time at the detector, this is due to Tx and Rx being closer or further from each other.

The large amplitude signals are SAW signals that I want to filter out.

I have used:

FMC(FMC < -2e-4)=0;

FMC(FMC > 2e-4)=0;

It works ok, however, I want to refine it based on the calculated arrival time of the SAW (t = d/v) with t = time, d = distance and v = velocity of the ultarsonic signal.

I can calculate the arrival time based on the distance of each Tx and Rx combination for each row, however, some arrival times are between the time intervals of 20ns. Is it possible to round up 3.95270270270270e-06 to 3.96e-06 as this would correspond exactly with one of the time stamps.

I want to convert that time stamp, with n to the left and to the right to zero.