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EFDO (EIA422 Differential I/O) Terminator Multimode Encoder Signal Filters
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Represent/distribute this product Request further information or a quote Read Eliminating Phantom Movement in Encoder Applications paper Product Leaflet (pdf) Encoder filter FAQ (Frequently Asked Questions) Buy EFDO models online
The EFDO filters process line-driver differential EIA422 signals to generate universal 5 V signal outputs (EIA422 and all single-ended types) in various, user selectable modes. (The filter technology overview and all other models are covered here).
Terminator Multimode Encoder filter
Terminator multimode encoder signal filter

The filters remove all types of electrical noise (common and differential mode, dV/dt transients, ground loop generated etc.) in the encoder signal lines as well as the corrupting effects of mechanical noise and vibration (phantom movement, dither etc.). They reconstruct the encoder signals to reflect the correct encoder position and speed signaling. Performance is safeguarded and problems such as:
  • Motion system position drift,
  • Home reference loss,
  • False triggering of the receiving inputs, and
  • Receiving input saturation, latch-up or failure
are eliminated. (The subject is treated extensively and in detail in our paper Eliminating Phantom Movement in Encoder Applications).  See also the Frequently Asked Questions page.

Like all other Terminator multimode filters, they are standard, all-in-one, comprehensive products, each device addressing all and any combination of known encoder application issues.  The filters process digital quadrature encoder signals with the following features:

  1. Unfiltered: the outputs are buffered replicas of the inputs,
  2. Filtered: the encoder inputs are processed for electronic noise only,
  3. Recovered x1: the encoder inputs are processed for electronic noise and analyzed for mechanical position to recover corrupted motion sequences. The outputs are in quadrature format and the mark (or index) channel is processed for electrical noise.
  4. Recovered x4: Same as the Recovered x1 mode, but with output resolution quadrupling. The output signals are a clock/direction or an up/down pair at four times the input frequency instead of the quadrature format.

The above all-in-one, multimode approach is justified when considering that in practical applications there is typically more than one mechanism at play eroding encoder performance at any time (see our paper on this or the encoder filter FAQ page). This makes a multimode filter the only effective, efficient, viable and conclusive solution to encoder noise problems.

The EFDO filters are available in Standard and High speed grades. The speed grade specifies the maximum quadrature input frequency which can be processed. The limit is different for each filter mode:

Maximum Quadrature Input Frequency Capability per Filtering Mode
Speed Grade Unfiltered Mode Filtered Mode Recovered x1 Mode Recovered x4 Mode
Standard 10 MHz 1.5 MHz 1.2 MHz 375 kHz
High 10 MHz 3.0 MHz 2.4 MHz 1.5 MHz

The filter design is characterized by typical industrial application considerations: minimal cost, standard interfacing, fool-proof installation and operation. Like all our encoder filters, the EFDO features the following:

You can buy small quantities of the EFDO model online here.

Download PDF leaflet or request further information or a quote/offer

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