Remote sensors : clamping diodes and input filtering?

[nickagian]

In a data-logger I am designing right now the sensors will be placed some 3 meters away from the central unit. I'll have an RTD PT1000, a capacitive humidity sensor, a digital pressure sensor and two strain gauges.

I have two questions on this configuration, regarding two topics that I'm not very familiar in :

1) Do I need any clamping diodes at the connection point of the sensors to the PCB?
2) Any filtering before the amplification stage? I'm mostly concerned on EMI (both inductive and conductive). Are filters really necessary? For example the NFM21C or the BLM series of Murata.

Nick

 

[dick_freebird]

You might prefer to put signal-conditioning circuitry at
the remote end, if it can stand the environment. At least
enough to get the signal to full span before traversing the
long wire, so as to maximize SNR (minimize effect of
incident EMI).

 

[nickagian]

You might prefer to put signal-conditioning circuitry at
the remote end, if it can stand the environment. At least
enough to get the signal to full span before traversing the
long wire, so as to maximize SNR (minimize effect of
incident EMI).

I agree that this would be the best idea, but unfortunately it can't be done. There is no space for putting signal conditioning circuitry at the remote end. I can only afford the sensors themselves. The signal conditioning electronics have to be put at the data-logger.