switch 58 can ask a respective bandwidth filter 38 40 or 42 to a gnss receiver e g via a block amplifier 12 if interference is detected in one of these bands by the detection circuit 44 the filter bank 32 will be switched accordingly and the receiver will not operate in the interfering bandwidth although other signals will still be usable in a normal lna the presence of a strong jamming interference signal would block all of these signals by saturation of the lna an interference avoidance lna 60 comprising an alternative aspect or embodiment of the present invention is shown in fig4 and includes a receiver 66 coupled to or including a tone decoder or level detector 62 adapted for detecting a tone a level change or a change in dc which can be communicated through the same coaxial cable 68 to an lna 64 with a change in dc bias voltage or a low frequency tone for example a filter bank 72 includes first second and third bandpass filters 74 76 78 respectively a frequency selection switch 80 and an output selection switch 82 are connected to the filter bank 72 and are similar to the switches 36 58 described above the switches 80 82 can be operated by a logic circuit similar to the logic circuit 56 described above it will be appreciated that the components of the system 2 can be used for various other applications moreover the subsystems units and components of the system 2 can be combined in various configurations within the scope of the present invention.