The video shows an example of interference control when monitoring a thick-walled object with a thickness of 300 mm.
At a high frequency of sending a probing pulse, a situation may arise in which the radiation emitted in the previous cycles of the probing pulse does not have time to fade, and due to re-reflections in the object of control, it may be registered in the current receiving/transmitting cycle. The flaw detector processes such echoes as corresponding to the current receiving/transmitting clock. This leads to false indications on the S-scan.
When the frequency of the parcels decreases, the arrival time of the pulses that form false indications changes. As a result, the false indication changes its position on the S-scan, while the position of the indications formed by the echoes of the current receive/transmit clock does not change.
You can select a frequency of parcels at which false indications will be absent on the S-scan.
It should be noted that with a decrease in the frequency of parcels, the speed of data collection decreases.