Communication system with control signal based tuning

A method of adjusting a filter characteristic of a tuneable filter of a communications device, the method comprising the steps of:

• a) tuning the tuneable filter of the communications device to receive a control channel signal transmitted at an accurate frequency by a base station responsible for the control of said communications device;
• b) establishing a centre for a passband of the tuneable filter using the accurate frequency of the control channel signal;
• c) adjusting said filter characteristic to a minimum insertion loss at said centre of the passband, thereby optimising selectivity and sensitivity for the communications device;
• d) subsequently tuning the tuneable filter to selectively receive a traffic channel signal, from a plurality of traffic channel signals transmitted by said base station, by filtering all but a selected traffic channel signal of said plurality of traffic channel signals.

A method of adjusting a filter characteristic of a tuneable intermediate frequency filter of a radio communications receiver, the method comprising the steps of:

• a) supplying a parameter to the tuneable filter by means of a digital-to-analog converter to provide a first filter characteristic;
• b) tuning the tuneable filter to receive a control channel signal transmitted at an accurate frequency by a base station responsible for the control of said communications receiver;
• c) establishing a centre for a passband of the tuneable filter using the accurate frequency of the control channel signal;
• d) supplying to the tuneable filter a new parameter representative of a new filter characteristic, thereby adjusting said filter characteristic to a minimum insertion loss at said centre of the passband and optimising selectivity and sensitivity for the communications receiver;
• e) subsequently tuning the tuneable filter to selectively receive a traffic channel signal, from a plurality of traffic channel signals transmitted by said base station, by filtering all but a selected traffic channel signal of said plurality of traffic channel signals.