Tuning of filters

A method for tuning a radio or microwave frequency filter by a control apparatus, comprising:

• obtaining, by the control apparatus, information indicating at least one reference characteristic;
• obtaining input data, the input data relating to an output of the tunable filter;
• determining, based on the input data, at least one characteristic of the tunable filter, wherein determining the at least one characteristic further comprises:
• determining, based on the input data, a filter transfer function, and determining, as the at least one characteristic, a filter coupling matrix on the basis of a structure of the tunable filter and the filter transfer function;
• upon detecting that the at least one determined characteristic does not match with the at least one reference characteristic, determining tuning instructions for the tunable filter;
• applying the tuning instructions in adjusting the tunable filter;
• comparing the determined filter coupling matrix against a reference coupling matrix defined by the at least one reference characteristic;
• and
• upon detecting, based on the comparison, that the filter coupling matrix does not match with the reference coupling matrix, determining the tuning instructions for the tunable filter.

A method for tuning a radio or microwave frequency filter by a control apparatus, comprising:

• obtaining, by the control apparatus, information indicating at least one reference characteristic;
• obtaining input data, the input data relating to an output of the tunable filter;
• determining, based on the input data, at least one characteristic of the tunable filter;
• upon detecting that the at least one determined characteristic does not match with the at least one reference characteristic, determining tuning instructions for the tunable filter;
• applying the tuning instructions in adjusting the tunable filter;
• obtaining information on interrelationships between different tuning parameters of the filter, the information indicating how an adjustment of a given tuning parameter affects the tuning of another tuning parameter;
• and
• determining tuning instructions further on the basis of the information on interrelationships.