Tuning of Filters

Abstract

There is provided a method, including obtaining information indicating at least one reference characteristic; obtaining input data, the input data relating to the 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; and applying the tuning instructions in adjusting the tunable filter.

1 .- 12 . (canceled) 
     
     
         13 . An apparatus, comprising:
 at least one processor and at least one memory including a computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to perform operations comprising:   obtaining information indicating at least one reference characteristic;   obtaining input data, the input data relating to the 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; and   applying the tuning instructions in adjusting the tunable filter.   
     
     
         14 . The apparatus of  claim 13 , wherein the reference characteristic is obtained from a reference filter, which represents a filter which is tuned to produce an acceptable reference output. 
     
     
         15 . The apparatus of  claim 13 , 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.   
     
     
         16 . The apparatus of  claim 15 , wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to perform operations comprising:
 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   
     
     
         17 . The apparatus of  claim 13 , wherein the input data comprises at least one measured scattering parameter of the output of the tunable filter. 
     
     
         18 . The apparatus of  claim 13 , wherein tuning instructions comprise instructions for adjusting at least one tuning parameter of the filter, wherein the tuning parameter comprises at least one of a frequency of a resonator of the filter, a coupling between two resonators of the filter, a coupling of an input of the filter, and a coupling of the output of the filter. 
     
     
         19 . The apparatus of  claim 13 , wherein the adjustment comprises adjusting a plurality of tuning parameters of the filter in parallel. 
     
     
         20 . The apparatus of  claim 13 , wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to perform operations comprising:
 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.   
     
     
         21 . The apparatus of  claim 20 , wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to perform operations comprising:
 obtaining a threshold indicating a distance above which the interrelationships between different tuning parameters are not considered.   
     
     
         22 . The apparatus of  claim 13 , wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to perform operations comprising:
 performing the tuning of the filter in a plurality of cycles, each cycle comprising the steps of re-determining the at least one characteristic on the basis of new input data, determining new tuning instructions for the tunable filter, and applying the new tuning instructions in the adjustment of the tunable filter; and   considering that the tuning of the filter is accomplished when the at least one re-determined characteristic matches with the at least one reference characteristic according to a predetermined tuning accuracy.   
     
     
         23 . The apparatus of  claim 13 , wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to perform operations comprising:
 detecting at least one loose tuning screw; and   providing an indication of the loose tuning screw to a user.   
     
     
         24 . The apparatus of  claim 13 , wherein the adjustment is performed by a filter tuning unit comprising:
 at least one motor for screwing at least one of a plurality of screw drivers of the filter tuning unit; and   a filter specific adapter plate providing through-holes coinciding with the locations of tuning screws of a given tunable filter, wherein the at least one screw driver penetrates at least one through-hole.   
     
     
         25 . (canceled) 
     
     
         26 . A system for tuning a radio frequency or a microwave filter, comprising:
 a filter analyser for measuring an output of the filter and providing information of the output to a control apparatus;   the control apparatus comprising:
 at least one processor and at least one memory including a computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to perform operations comprising: 
 obtaining information indicating at least one reference characteristic; 
 obtaining input data, the input data relating to the output of the filter; 
 determining, based on the input data, at least one characteristic of the 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 filter; and 
 outputting the tuning instructions in adjusting the filter; and 
   a filter tuning unit for tuning the filter according to the tuning instructions obtained from the control apparatus.   
     
     
         27 . (canceled)