(1) (Product Data Management) An information system used to manage the data for a product as it passes from engineering to manufacturing. The data includes plans, geometric models, CAD drawings, images, NC programs as well as all related project data, notes and documents. A PDM also manages the interrelationships between the data so that when changes are made to one database, the effects are highlighted in the others. PDMs are developed for workgroups as well as the entire enterprise. See PLM.
(2) (Pulse Density Modulation) A modulation technique that generates fixed-width pulses to represent the amplitude of an analog input signal. Like its variable-width pulse width modulation (PWM) cousin, the output switching transistor is on more of the time for a high-amplitude input signal and off more of the time for a low-amplitude signal. PDM is used for audio signals in a variety of applications from cellphones to Sony's SACD music format. See PWM and Class D amplifier.
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