The speed at which the continuously variable quantity (output voltage or current) follows the object position. Two methods are typically used to measure this: step response and frequency response. Step response is the time (typically in ms) required for the voltage or current to change to a certain percent of the final value. Frequency response is another way to measure analog response. Imagine a SUPERPROX analog sensor monitoring a rotating cam. As the cam rotates faster and faster, the unit becomes less accurate in its measurement. The frequency where the measured value of the difference between minimum and maximum is one-half the true difference is often used as a measure of frequency response. In Hyde Park's analog sensors, it is the change in analog output relative to the change in position of an object sensed within the Near and Far span limits of the Model SM506 or SM606 Series.