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I want to use a sensor with analog output in my design. The output of the sensor is a low frequency traingular wave (less than 300 Hz) and voltage vetween 0 - 5V. I need to carry the sensor signal to the controller through a cable, approximately 400mm in length. The sensor supply voltage and ground line also comes from the controller. I have following questions

  1. There is a strong noise source (motor windings) close by. How can I improve the noise immunity of the signal carried to my controller?
  2. The literature I have gone through suggests approaches like shielding, single ended to differential conversion or conversion to current signal. Is there any other approach available for this kind of situation?
Firebird207
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  • Can you digitise at source? – awjlogan Oct 04 '18 at 09:25
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    Send over [co-axial](https://en.wikipedia.org/wiki/Coaxial_cable) cable? – rdtsc Oct 04 '18 at 10:19
  • Digitization at source is an issue, because it will add time overhead required for communication. I do not wish to add delay between sensor output and my controller reading the same. It will be detrimental to my application. – Firebird207 Oct 04 '18 at 10:25
  • Try it by direct connection and see if there is too much noise. – Andy aka Oct 04 '18 at 10:36
  • What's wrong with the approaches you have found so far? – Dave Tweed Oct 04 '18 at 11:25
  • Nothing wrong per se in the approaches I found so far. I am also inclined towards single ended to differential conversion plus shielded twisted pair approach. Since the supply and ground will be carried along with the signals, I am thinking of 4 wire/2 twisted pair cable with shield. It's just that the signal is extremely critical for my application (i cannot use any kind of filter to cut out the noise due to the resulting phase shift in the signal) I want to use the best possible approach. – Firebird207 Oct 04 '18 at 12:53
  • Ensure the motor cables ---- HOT, RETURN --- are twisted pairs. Put those cables inside shields. Place capacitors at the motor ends of the cables. – analogsystemsrf Oct 05 '18 at 04:32

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