[EricVanWyk]

When I teach my students, I stress the difference between Pulse Width Modulation and Duty Cycle Modulation. It is a bit pedantic, but I feel that it helps to clear things up.

There are four measurements that can describe the timing of a square wave, but you can use any two to fully define it: duty cycle, frequency, positive width, negative width. The choice of which two depends heavily on the application, and helps separate the relevant factors.

PWM is dimensioned by the positive width (value) and the frequency (symbol rate). As frequency changes, the positive width stays the same to send the same information.

DCM is dimensioned by the duty cycle (applied 'voltage') and the frequency (allowed ripple). As frequency changes, the duty cycle stays the same to send the same average 'voltage' to the motor.

The microcontroller in a victor or jaguar measure the pulse width of the PWM signal from the cRIO and calculate an appropriate duty cycle for the DCM signal they send to motor through their bridge.

In mechanical terms, you can dimension a drawing many ways and produce the same part, but you may choose to show and hide a particular set to better communicate intention.