Units for time, frequency, and voltage

picoDAQ defines the classes Time, Frequency, and Voltage to represent times, frequencies and voltages.

Generally, you do not contruct instances of these classes directly, but use the constants s, ms, Hz, kHz, V, mV that represent, respectively, one second, one millisecond, one hertz, one kilohertz, one volt, and one millivolt.

For instance, to specify a pulse with amplitude 2.5 volt, you might write:

amplitude = 2.5*V

Arithmetic is fully supported. For instance, 3*s/2 + 3.5*100*ms is a valid way to represent 1.85 seconds.

The system also knows that time and frequency are reciprocal to each other. Thus, 10000/s and 10*kHz are both valid ways to represent 10 kilohertz.

To convert the dimensionless product of a time and a frequency back to a plain number, use the plain() method, as in:

from picodaq import *
duration = 10 * s
rate = 5 * Hz
pulsecount = int((duration * rate).plain())

(Without the explicit int cast, the result would be float.)

Implementation detail

Time, Frequency and Voltage are implemented as derived classes from a general Quantity class. Most users do not need to use that class directly.