FREQUENCY & PHASESHIFT
In many sensory applications the value of interest (capacity, resistance, weight, density, pressure ...) is converted to a frequency change or phase shift. Typical examples are capacitive or inductive proximity sensors or piezoelectric weighing cells.
Take as an example the frequency measurement with the help of the TDC-GP1: connect the frequency signal (should be TTL) simultaneously to the start and stop inputs of the GP1 - that's all! You directly measure the period. Depending on the accuracy requested, this can be realized with lowest current consumption - ideal for battery driven equipment. The table shows some typical values for accuracy and current consumption in the two measuring ranges.
|Periods .||Freq||Resolution |
(1 measure-ment per second)
(sampling1000 measurements per sec)
|mes. range2||min||60ns||16.7MHz||0.5%||400nA .||0.015%||550uA|
1 LSB = 120ps
*calibration clock active only during measurement
In the same way it's possible to measure the jitter of a frequency signal or the phase shift between two signals - with up to 2.5 million measurements per second