a traffic alert and collision avoidance system uses a dual bandwidth receiver to achieve extended range operation . during normal operations tcas radio signals are filtered by a bandpass filter which passes all tcas radio signals of interest . when extended range operation is desired the tcas radio signals are filtered by a more narrow bandpass filter . the narrower filter passes only selected tcas radio signals and improves the signal to noise ratio and thus allows detection of selected tcas radio signals at extended range . the tcas system switches between the normal mode and the extended range mode to detect and track aircraft at both near and far distances .