TECHNICAL REFERENCE
TRANSMIT PULSE
The XPL+ transmit pulse consists of one or more electrical "shot" pulses, which are supplied to the scanning
relays. The scanning relays are activated as required, to supply the transmit pulse to the appropriate
transducer connected to the XPL+ 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
( removing noise, P821 and P822 ) and
reforming
( connecting
fragmented echo peaks, 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 ( Empty Distance P006 + 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 automatically achieved by comparing the position ( relation in time after transmit ) of
the "new" echo to the previously accepted echo position.
If the new echo is within the Echo Lock Window ( P713 ), the new echo is accepted and displays, SAM-20
relays and AO-10 mA outputs, 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
( measurement repeatability, P711 ) requirements are satisfied.
ECHO PROCESSING DISPLAYS ( Scope Displays, P810 )
Echo Lock
Window
Echo
Marker
TVT Curve
Echo Profile
Near Blanking
( P 800 )
Empty Distance ( P006 ) +
Range Extension ( P801 )
msec x 100
TECHNICAL REFERENCE
PL-532 83
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