Filter having frequency-dependent transmission properties for electric analog signals

A filter having a filter function for discrete electric signals corresponding to the frequency-dependent transmission properties for electric analog signals of an analog LC-network of predetermined configuration and having predetermined impedance-representing constants,

• said filter comprising
• a. a basic filter circuit having a plurality of port elements with ports each including a port input and a port output,
• b. at least one of said port elements being a one-port element, said one-port element comprising time delay means having a predetermined time delay, said time delay means being connected between the port input and the port output of the one-port element and being operable for receiving an input signal from the port input of the one-port element, and for supplying an output signal to the port output of the one-port element in accordance with said input signal but delayed by said predetermined time delay;
• c. said plurality of port elements of said basic filter circuit comprising further port element means including further port input means and further port output means, and
• d. said basic filter circuit comprising interface device means interconnecting said port elements, said interface device means having a set of interface ports comprising first and second interface ports each with an interface port input and an interface port output, the interface port input and the interface port output of the first interface port being connected respectively with the further port output means and the further port input means of the further port element means, and the interface port output and the interface port input of the second interface port being connected respectively with the port input and the port output of said one-port element,
• e. said interface device means comprising interface circuitry including adder means and multiplier means connected with the set of interface ports and connecting the interface ports of the set together in a connective relationship which is in accordance with the configuration of said analog LC-network,
• f. said interface circuitry having a multiplier coefficient for each said multiplier means correlated with the connective relationship of said set of interface ports and with the impedance-representing constants of analog components of the LC-network corresponding to the port elements interconnected by said set of interface ports, and
• g. said further port element means comprising further time delay means providing a further time delay which is a function of said predetermined time delay, said further time delay means being interposed in said further port element means so as to be in series with said interface circuitry to prevent the existence of a feedback loop without time delay via said further port element means and said interface circuitry.