Siemens LU01 instruction manual Technical Reference, Transmit Pulse, Echo Processing

Technical Reference

Transmit Pulse

The SITRANS LU01 transmit pulse consists of one or more electrical shot pulses, which are supplied to the scanning relay. The scanning relay is activated as required, to supply the transmit pulse to the Transducer(s) connected to the SITRANS LU01 terminals.

The transducer fires an acoustic shot for each electrical pulse supplied. After each shot is fired, sufficient time is provided for echo (shot reflection) reception, before the next (if applicable) shot is fired. After all shots of the transmit pulse are fired, the resultant echoes are processed.

The transmit pulse shot number, frequency, duration, delay, and associated measurement range are defined by parameters P803 and P840 to P852.

Echo Processing

Echo processing consists of echo enhancement, true echo selection, and selected echo verification.

Echo Enhancement is achieved by filtering (P821 and P822) and reforming (P823) the echo profile (digitized signal representing the echo signal received).

True echo selection is achieved by establishing the criteria which a portion of the echo profile must meet to be considered the true echo (echo reflected by the intended target).

Insignificant portions of the echo profile outside of the measurement range (Span P007 + Range Extension P801), below the TVT Curve (P830 to P835), and less than the Confidence Threshold (P804) and Short Shot Floor (P851) are automatically disregarded.

The remaining portions of the Echo Profile are evaluated using the Algorithm(s) (P820) and Short Shot Bias (P850) programmed. When a combination of Algorithms are used, the portion of the Echo Profile providing the best averaged Echo Confidence (P805), is selected as the true echo.

True echo verification is automatic. the position (relation in time after transmit) of the new echo is compared to that of the previously accepted echo. When the new echo is within the Echo Lock Window (P713), it is accepted and displays, outputs, and relays are updated as restricted by the Fuzz Filter (P710) and Rate Parameters (P700 to P703). If the new echo is outside of the Echo Lock Window, the new echo is not accepted until Echo Lock (P711) requirements are satisfied.

Technical Reference

7ML19985BE02 SITRANS LU01 – INSTRUCTION MANUAL Page 85