Receiving signals from both GPS and Galileo systems

A receiver receives a GPS signal (1 ,Fig.1) having a first frequency spectrum with principal energy (3,Fig.1) in a first frequency band (6,Fig.1) and a Galileo signal (2,Fig.1) having a second frequency spectrum with principal energy (4,Fig.1) in second and third frequency bands (5,7,Fig.1). The receiver comprises a frequency shifting means, and filters (10a,b,Fig.2) having frequency responses comprising first and second passbands (11,12,Fig.3) separated by a central stopband (13,Fig.3). When receiving a GPS signal, the frequency shifting means shifts the incoming signal such that the first frequency band 32 of the GPS signal lies in either of the first and second passbands 31, and one of the second and third frequency bands 33 of the Galileo signal is shifted onto the central stopband. When receiving a Galileo signal, the frequency shifting means shifts the incoming signal such that the second and third frequency bands 43 of the Galileo signal are shifted onto the first and second passbands 41 respectively, and the first frequency band 42 of the GPS signal is shifted onto the central stopband. Thus the filter remains static and there is no need to provide separate filters for GPS and Galileo reception.