A pulse Doppler radar is the result of combining Doppler sensing techniques with pulsed radar operation. Such radars offer the powerful scope for direct measurements of both target range and velocity, even in the face of large clutter returns and even in the presence of chaff or other interference. To radar, the measurement of a time delay is tantamount to range, whereas the measurement of a (Doppler) frequency shift is tantamount to velocity. Thus, one must consider the design of suitable waveforms in both the time and frequency domains. However, there is a complex interplay between the waveform parameters, particularly when it comes to the selection of the radar pulse repetition frequency (PRF). All too often, the requirements for the measurement of range clash with those for the measurement of velocity. The result is that multiple waveforms may be required which depend on the nature of the targets and clutter conditions. The study of pulse Doppler radar is thus inextricably bound up with issues of waveform design and their associated processing methods whilst always maintaining a watchful eye on the target scenario and radar environment. Before tackling these waveform and processing issues, it is necessary to establish several fundamental radar concepts, which are covered in the ensuing chapters.