Radar is a common detection system for detecting the speed and velocity of moving objects. Radar is performed by transmitting a radio signal in the direction of a moving object and then processing the received reflected radio waves. The radar system processes the received signal to extract the Doppler frequency of the reflected waves, which reveals information about the velocity of the object. In traditional radar, the system uses one antenna for both the transmitter and the receiver. In

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... bistatic radar, the transmit antenna and receiver antenna are separated. In addition, the radar system has no control over the transmitter. The transmitted signal is instead a signal of opportunity. Signals of opportunity include FM and AM radio signals, satellite GPS signals, and WiFi signals. The receiver in the radar system receives a signal of opportunity and extracts the Doppler frequency from the signal. The Doppler frequency can then be used to get the velocity of the object, which can be used for tracking the object. In previous research, the methods of traditional radar were applied to passive bistatic radar using a WiFi signal in order to track a moving object within a building. Traditional radar methods are to compare the Doppler-shifted signal to the original signal. In passive radar, the original signal needs to be measured without being affected by the Doppler-shifted signal, which requires a second antenna to be placed by the transmitter. The research presented suggests a new method of retrieving the Doppler frequencies from a communication signal. This new method does not require a separate antenna to get the original signal but uses knowledge about the communication signal to successfully measure the Doppler frequency on the signal. The system was implemented using GNURadio, a software-defined radio library. Additional processing was done using MATLAB.