An encoder is a device, circuit, transducer, software program, algorithm or person that converts information from one format or code to another, for the purpose of standardization, speed or compression.
- A compressor encodes data (e.g., audio/video/images) into a smaller form (see codec)
- An audio encoder converts analog audio to digital audio signals
- A video encoder converts analog video to digital video signals
- A multiplexer combines multiple inputs into one output
- An 8b/10b encoder creates DC balance on a communication transmission line
Transducers (such as optical or magnetic encoders) sense position or orientation for use as a reference or active feedback to control position:
- A rotary encoder converts rotary position to an analog (e.g., analog quadrature) or digital (e.g., digital quadrature, 32-bit parallel, or USB) electronic signal.
- A linear encoder similarly converts linear position to an electronic signal.
Such encoders can be either absolute or incremental. The signal from an absolute encoder gives an unambiguous position within the travel range without requiring knowledge of any previous position. The signal from an incremental encoder is cyclical, thus ambiguous, and requires counting of cycles to maintain absolute position within the travel range. Both can provide the same accuracy; the absolute encoder is more robust to interruptions in transducer signal, whereas the incremental encoder reports position changes in real time.
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- ASIC-World's Digital Combinational Logic (part III) – an overview of encoders in circuitry.