A method for generating a synthetic data signal is described. A synthetic data signal having any desired duration is generated from a data signal and a background signal of shorter duration. The duration of the background signal is extended by sampling the background signal at random times and for random durations. The sampled background signal is used to extend the background signal. Event data is identified from the data signal. The extended background signal is randomly populated with event data randomly sampled from the data signal to generate the synthetic data signal.