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Twisted Shielded Pair Wiring

For the instrumentation amplifiers to achieve the best noise rejection it is essential that any noise induced in the wiring be common mode. This is best achieved by the use of shielded twisted pair wiring between the sensor or signal source and the instrumentation front-end. It is important to note that not all "shielded pair'' cable are in fact twisted. Cables where the wire pairs simply run parallel to each other are significantly more susceptible to induced normal mode noise caused by fluctuating fields as well as cross coupling between adjacent pairs. The use of shielded twisted pair cable is strongly encouraged.

The telephone industry is a testament to the noise immunity that can be achieved through the use of twisted pair cable and differential signaling. They run twisted pair cable for miles along power lines and open country with thunder storms and achieve amazingly low crosstalk and noise pickup ... remember the human ear is a marvelous device with a logarithmic response so even the smallest amount of noise or crosstalk can be objectionable.

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