Point Velocity Display PVD100

The Hydrological Services Point Velocity Display (PVD100) is a small electronic device used to "clean" the signal from a mechanically rotating
current meter such as a Price AA or Pygmy meter and directly reads the velocity on the LCD as well as interfacing to a PDA for computation of velocity and discharge. Meters using a cat whisker head and ball and wire contact to perform a mechanical switch closure can be used with the PVD100 to produce a clean, noise-free signal. Whenever the PVD100 is connected to a hand-held computer and the current meter bucket wheel completes a contact closure, the PVD100 can
simultaneously produces four responses:
1) Sounds a buzzer tone;
2) Emits a flash from an LED indicator on the front panel,
3) Updates the LCD count and timer, and
4) Transmits a serial data value at 1-second intervals representing the number of contact closures and elapsed time through the serial interface.

The PVD100 uses two AA batteries for operation and is connected between the current meter and the hand-held computer using either a connecting lead or an optional Bluetooth wireless interface. A program running in the hand-held computer sends commands to the PVD100 to perform a measurement.

Special points of interest:
- Direct Velocity Reading
- User Serial Interface Program for entering 2 current meters with up to 3 rating equations for each current meter.
- The ability to signal process each contact closure from any type of meter. For cat whisker contacts, this becomes extremely important since cat whisker contacts offer the poorest quality for marking and counting rotations.
- The PVD100 offers (2) modes of operation, i.e. NORMAL and SLOW speed mode. NORMAL is selected for meter rotations >0.25 ft/sec while SLOW mode is for velocities below 0.25ft/sec. To improve noise rejection, the sample rate of the input signal at the SLOW speed mode (lower velocities) is 1/10 of the sampling rate that occurs during NORMAL mode.
- The ability to detect faulty connections from the meter through the wading rod to connected PVD100. During power up of the PVD100, a calibration of the input signal is performed.
- The ability to detect a signal short during a measurement. If such a condition is detected, the �*� symbol is displayed until the fault condition is removed.