TABLE OF CONTENTS Pulse repetition interval timing is one of the major aspects of ELINT signal analysis. The radar s performance is affected significantly by the PRI timing used. In addition, many warning receivers and jammers make use of properties of the PRI. Finally, PRI data can generally be recorded easily for off-line analysis in the laboratory. Most PRI values are such that modest bandwidths can be used. Generally, the video or envelope bandwidth is of interest for recording or digitizing the PRI (and pulse duration) data. It is normally the case that the video bandwidth is approximately one-half of the two-sided predetection or IF bandwidth; however, as noted in Chapter 3, in the case of a wideband receiver, the video bandwidth may be small compared to the RF bandwidth of the receiving system.
The radar pulse is usually repeated; however, the interval between pulses may change. It is common to speak of the PRI used by radar even though the interval itself may not be repeated. In this discussion, the term PRI is used to mean the time from the leading edge of one radar pulse to the leading edge of the next radar pulse. For radar systems that use groups (or bursts) of several closely spaced pulses, the PRI refers to the time from the leading edge of the first pulse in one group to the first pulse in the next group. This may be referred to as the pulse group repetition interval (PGRI).
Just as close scrutiny of the...
