RF (including GNSS) signal interference mitigation system and method
An RF (e.g., GNSS) interference mitigation system and method uses a switchable bank of filters for selectively blocking signals in predetermined bandwidths based on detecting strong, interfering signals with an interference detection circuit including a sniffer antenna. A low-strength RF (e.g., GNSS) system can be combined with a spectrally-close high-strength, telecommunications receiver system for cooperative control. Alternatively, an RF receiver can detect tones, changes in DC bias or level changes to activate a filter selection switch.
1. An interference avoidance low noise amplifier (LNA) for a radio frequency (RF) antenna and receiver system, which LNA includes:
multiple bandpass filters selectively connectable to an RF antenna element and to an output connected to an RF receiver, each filter corresponding to a respective RF bandwidth;
a sniffer antenna adapted to detect RF interference signals in a respective RF band;
a logic circuit connected to the sniffer antenna and adapted to select a respective bandwidth based on an interference signal detected by said sniffer antenna;
an automatic switch activated by said logic circuit and adapted to connect said antenna element and said antenna output to a respective bandpass filter;
a receiver selecting the bandwidth selected by the logic circuit for switching out based on a change in direct current (DC) bias;
a solution processor for detecting an interfering signal and switching out a respective frequency bandwidth in response to said detected interfering signal;
said solution processor includes a logic circuit adapted to select the switched-out bandwidth based on interference power;
said logic circuit utilizes multiple bandpass filters for detecting an interfering signal and providing a corresponding signal to said logic circuit for activating a respective filter connected to said antenna element; and
said solution processor including a signal processing function connected to an RF receiver and adapted for selecting a bandwidth in use and blocking a bandwidth not in use by the receiver.
2. The interference avoidance LNA according to claim 1 , which includes:
said RF receiver being configured for receiving global navigation satellite system (GNSS) positioning signals.
3. A method of avoiding interference with a low noise amplifier (LNA) for a radio frequency (RF) antenna and receiver system, which method includes:
providing multiple bandpass filters selectively connectable to an RF antenna element and to an output connected to an RF receiver, each filter corresponding to a respective RF bandwidth;
providing a sniffer antenna adapted to detect RF interference signals in a respective RF band;
providing an automatic switch activated by said logic circuit and adapted to connect said antenna element and said antenna output to a respective bandpass filter;
providing a solution processor with a logic circuit for detecting an interfering signal and switching out the bandwidth selected by the logic circuit;
providing a receiver selecting the bandwidth selected by the logic circuit for switching out based on a change in direct current (DC) bias;
said logic circuit utilizing multiple bandpass filters for detecting an interfering signal and providing a corresponding signal to said logic circuit for activating a respective filter connected to said antenna element; and
said solution processor including a signal processing function connected to the RF receiver and adapted for selecting a bandwidth in use and blocking a bandwidth not in use by the receiver.
4. The interference avoidance method according to claim 3 , which includes:
said RF receiver receiving global navigation satellite system (GNSS) positioning signals.