I have an analog sensor, a resistance temperature thermometer, which is essentially just a resistor (~50 Ω) which I apply a constant current to (10 mA) and measure the voltage of in order to detect temperature changes.

The temperature changes of interest are extremely small, and so it is extremely sensitive to electrical interference, and nearby there are many pumps and stepper motors. I have been told conflicting information about how the cable should be shielded. 

The two options are: (diagram attached also)

**A: COAXIAL CABLE**
I have up to now been using a coaxial cable. The outer of the cable is connected to ground at the oscilloscope I use to record data. The outer is carrying the return current, which I have been told is bad.

**B: SHIELDED TWISTED PAIR**
The constant current is carried in the internal twisted pair with a shield connected to ground at the oscilloscope end.

[![Coaxial vs. shielded twisted pair](https://i.stack.imgur.com/BgSZE.jpg "Coaxial vs. shielded twisted pair")](https://i.stack.imgur.com/BgSZE.jpg "Coaxial vs. shielded twisted pair")