Transient Variable Area Downhole Inverse Models - Measurement While Drilling Signal Analysis, Optimization and Design - page 149

Figure 5.1d . Phase-shift-keying, 96 Hz carrier wave.
5.1.6 Run 4. Short rectangular pulse with rounded edges.
For this 0.5 sec pulse, the black curve is successfully recovered and looks
like the green assumed curve. The red curve clearly shows distortions at the
front and tail end of the pulse. These are due to multiple reverberations inside
the collar due to area impedance mismatch at the collar and drillpipe junction.
C CASE 5. Short rectangular pulse with rounded edges.
IF(NCASE.EQ.5) THEN
IF(T.LE.0.0) DELTAP = 0.
IF(T.GT.0.0) THEN
AMP = 0.4
R = 200.0
DELTAP = AMP*(TANH(R*(T-0.01))-TANH(R*TANH(T-0.51)))
ENDIF
ENDIF
Figure 5.1e . Short rectangular pulse with rounded edges.