4       Tips for using QProny

In this section we shall give a set of recommendations for making the best use of QProny:

·       Do not use QProny for the analysis of wideband phenomena or low Q circuits.

·       The module does not accelerate the finite-difference time-domain method itself. So, if you use very fine meshing and the time step is small, the module will not cut down the simulation time if your circuit characteristics do not have narrow band features.

·       If possible, limit the spectrum of the source signal to 15%-20%.

·       Do not test for the energy drop too often. Not only does it slow down the simulation, but also may lead to confusing warnings, especially if beating takes place. The frequency of the testing, expressed in the periods of the center frequency signals, should be at least 0.2 of the anticipated value of Q.

·       Do not press the model creation Yellow Light button if beating is reported and the warning shows that the energy of the signal increases.

·       Watch the QProny window status bar while the model is being constructed. If the effective model orders displayed differ significantly, the quality of the model is probably not satisfactory.

·       Overmodelling is less harmful than undermodelling.

·       Very often good models can be created even if warnings are displayed. On the other hand it may happen that the quality of the model is unacceptable even if the model was created by pressing a Green Light button. It is therefore judicious to always verify the model by creating a new one when more samples become available.

In some cases, especially when the circuit has two poles located close to each other and the testing takes place frequently, the Green Light my change back to the Yellow one. This is a correct behaviour of the diagnostic procedures.