Method and a device for maintaining the performance quality of a code-division multiple access system in the presence of narrow band interference

A method for suppressing narrow band interference in a wideband telecommunications system, said system being operable in a wide frequency band, comprising the steps of:

• rapidly analyzing said wide frequency band with respect to signal power levels in specified narrow frequency bands and detecting said narrow band signal power levels received within said specified bands,
• deriving an average composite wideband power level from said narrow band signal power levels;
• using said signal power levels to derive an adaptive threshold for identifying said narrow band interference;
• and
• setting one or more notch filters for suppressing said identified narrow band interference.

A method of detecting and eliminating narrowband interference in a wideband communication signal having a frequency bandwidth with narrowband channels disposed therein, the method comprising:

• scanning at least some of the narrowband channels to determine signal strengths in at least some of the narrowband channels;
• determining a threshold based on the signal strengths in at least some of the narrowband channels;
• and
• filtering the wideband communication signal at a frequency corresponding to a narrowband channel having a signal strength exceeding the threshold.

A system adapted to detect and eliminate narrowband interference in a wideband communication signal having a frequency bandwidth with narrowband channels disposed therein, the system comprising:

• a scanner adapted to scan at least some of the narrowband channels to determine signal strengths in at least some of the narrowband channels;
• a notch module adapted to receive the wideband communication signal and to selectively remove narrowband interference from the wideband communication signal to produce a filtered wideband communication signal;
• and
• a controller coupled to the scanner and to the notch module, wherein the controller is adapted to determine a threshold based on the signal strengths in at least some of the narrowband channels and to control the notch module to filter the wideband communication signal at a frequency corresponding to a narrowband channel having a signal strength exceeding the threshold.

A method of detecting, eliminating and reporting narrowband interference in a wideband communication signal having a frequency bandwidth with narrowband channels disposed therein, the method comprising:

• scanning at least some of the narrowband channels to determine signal strengths in at least some of the narrowband channels;
• determining a threshold based on the signal strengths in at least some of the narrowband channels;
• filtering the wideband communication signal at a frequency corresponding to a narrowband channel having a signal strength exceeding the threshold;
• storing a list of narrowband channels having signal strengths that exceed the threshold;
• and
• outputting the list of narrowband channels having signal strengths that exceed the threshold.

A method of selecting a threshold for use in detecting narrowband interference within a bandwidth of a wideband communication signal, the method comprising:

• tuning a receiver to a plurality of frequencies within the bandwidth having substantially no narrowband interference to produce a plurality of signal strength indications;
• comparing a threshold voltage to a voltage representation of each of the plurality of signal strength indications;
• setting the threshold voltage until the threshold voltage exceeds each of the plurality of signal strength indications;
• tuning the receiver to a frequency having narrowband interference to produce an interference signal strength indication;
• comparing the threshold voltage to a voltage representation of the interference signal strength indication;
• and
• ensuring that the voltage representation of the interference signal strength indication exceeds the voltage representation of the threshold.

An interference detection and suppression system adapted to detect and eliminate narrowband interference in a wideband communication signal having a frequency bandwidth with narrowband channels disposed therein, the system comprising:

• a notch filter for filtering the wideband communication signal at a frequency corresponding to a selected one of the narrowband channels;
• a bypass switch adapted to selectively bypass the wideband communications signal around the notch filter;
• a receiver adapted to be tuned to a narrowband channel and to produce a voltage signal strength indication pertaining to the channel to which the receiver is tuned;
• a threshold setting device adapted to produce a voltage signal representative of a threshold to which the device is set;
• and
• a comparator coupled to the receiver, the threshold setting device and the bypass switch, wherein the comparator controls the bypass switch to selectively bypass the notch filter based on a comparison of the voltage signal representative of the threshold and the voltage signal strength indication.

A method of detecting and suppressing interference in a wideband communication signal having a frequency bandwidth with narrowband channels disposed therein, the method comprising:

• tuning a receiver to a narrowband channel to produce a voltage signal strength indication corresponding to the channel to which the receiver is tuned;
• setting a threshold to produce a voltage signal representative of a threshold;
• selectively filtering with an adaptive notch filter a selected one of the narrowband channels based on a comparison of the voltage signal representative of the threshold and the voltage signal strength indication;
• and
• selectively bypassing a selected one of the narrowband channels based on a comparison of the voltage signal representative of the threshold and the voltage signal strength indication.