Exam PWD

Temporal Shaping of the PWD Pulse
In order to make more accurate measurements of the blood velocity, the temporal pattern of the pulse is typically repeated. This will result in a narrower bandwidth of the transmitted pulse, which can make more accurate velocity measurements. The number of repetitions is determined by Pulse Repeat. If set to 0, the size of the gate will determine the pulse repeat, limited by the Tx Max Pulses (PW).
 * Pulse Repeat
 * Tx Max Pulses (PW)

The transmit frequency of the PWD pulse is set through:
 * Frequency

Since the PWD line is repeatedly scanned at a high PRF, localized heat is deposited into the tissue. In order to meet the safety limits, the amplitude of the pulse should be reduced. The following voltage indexes determine how the amplitude will be adjusted for increased PRFs:
 * Voltage- HighPRF
 * Voltage- MedPRF
 * Voltage- LowPRF

Transmit Beam Forming
The focal point of the PW transmit is determined by Tx Focus Distance. If set to 0, the focal point would be at the center of the gate.
 * Tx Focus Distance

Since the PWD line is repeatedly scanned at a high PRF, localized heat is deposited into the tissue. In order to meet the safety limits, the aperture used for the transmission is reduced. Tx Aperture Cutoff cuts the aperture for PW transmissions. This is to reduce the acoustic output when the default calculated B-mode transmit aperture is too big for a PW transmission.
 * Tx Aperture Cutoff

Sequencing
The choice between mono (only PWD) and duplex (PWD and B-mode) sequences are made through Mode. A value of 0 only runs a B-mode sequence. A value of 1 runs a PWD mono sequence, and a value of two runs a PWD duplex sequence.
 * Mode

The scan line on which the gate is located is the PWD scan line and will be repeated in the sequence:
 * PW Line

When using the interrupted PWD duplex sequences, the ratio of PW scan lines to B-mode scan lines in the sequence is determined by:
 * Interrupt Ratio

The repetition period (and thus frequency) of the the scanning for the PWD scan line is determined by:
 * PRP

Processing

 * Baseline
 * Invert
 * WF
 * Num Init Samples (Duplex WF)
 * LRP
 * Correction Angle