Incorporating Digital Levels
Digital levels are unique instruments in that they are intended to con- strain the network in Rx, Ry, and Z. When you add a digital level it is fixed by default in the instrument list, for this reason. However, it does not fully constrain the solution, meaning that the solution is free to float and will not solve without additional constraints.
This can be solved in either of two ways. You can manually fix an additional instrument’s location. This is done by opening an instruments properties from the network list and modifying its degrees of freedom. Fix R, Y and Rz as shown.
Alternatively, the solution will do this for you automatically using the next instrument in the list if the network remains under constrained.