While Linear Variable Differential Transformers (LVDTs) are robust and inherently frictionless, and can be used in extremely harsh environments at cryogenic temperatures, they do have an inherent crosstalk challenge.
Used in power turbines, automation, hydraulics, nuclear reactors, and more, this crosstalk, or beating between channels, happens when LVDT signal cables are in too-close a proximity, resulting in frequencies of the oscillator in the signal conditioner slightly driving the excitation signal to each LVDT. When the cables are close, they may capacitively couple with each other, producing a low-frequency signal representing the difference between the frequencies of each oscillator -- which means there's noise or a repetitive slow drift. The issue is pronounced when LVDT pairs are used for redundancy, and the noise may be seen on one channel of the system.
The S1A signal conditioner by Alliance Sensor Group has a unique feature that eliminates crosstalk between sensors. Most signal conditioners use a master/slave setup to solve this problem, but if the master fails, the slaves revert back to their own oscillators and hence crosstalk can happen. With the S1A, if the master fails, the first slave becomes the new master. This maintains the integrity of the system.
The only loss suffered by the system with this solution is the loss of the original master channel, but the integrity of the other channels in a multiple-channel system is maintained. So far, this solution is unique to the Alliance S1A.