Digital radar signal processing involves the coversion of radar signals to digital form after IF amplification and phase sensitive detection.(CFAR) Constant False Alarm Rate is a way for adaptively adjusting the detection sensitivity for a radar signal by adjusting the threshold to maintain a constant false alarm rate in an area.CAT-21 is the ASTERIX message format for the distribution of ADS-B messages.CAT-48 is the ASTERIX message format for network distribution of radar plot and tracks from primary or secondary radars.CAT-240 is the ASTERIX message format for network distribution of rotating radar video distribution in ASTERIX.It is commonly seen in fire control radars. B-Scan is a view of radar video that shows azimuth along the horizontal axis and range along the vertical axis.Bistatic radar consists of a transmitter and receiver located at a distance comparable to that between the transmitter and the target.The process combines a number of input returns for each output using either a peak-picking, averaging or other method of combination. Azimuth Correlation may be employed if there are more input returns than required for display or processing, or if some degree of processing is required for filtering.The specific standards are given a CAT (Category) number, for example CAT 240 is the standard for radar video. ASTERIX: A family of standards for radar data formats, originally developed for Air Traffic Control in Europe, but now used more widely for radar video and track format exchange in other market sectors.ADS-B: Automatic Dependent Surveillance Broadcast (ADS-B) is a method used by aircraft to report their GPS-derived position to a remote receiver, allowing the aircraft to be identified and tracked.The angle of the radar is therefore derived by counting the number of ACP pulses since the last ARP pulse. The ARP (Azimuth Reset Pulse) is a reset pulse that occurs at a reference point. Commonly there are 2048, 4096 or 8192 pulses per 360 degrees. The ACP (Azimuth Change Pulse) is a pulse train where the interval between pulses is a fixed angle. ACP/ARP are sets of pulses used to encode the bearing/azimuth angle of the radar antenna.The trace is updated for each azimuth at the pulse rate of the radar. It shows signal intensity on the vertical axis and range (time) along the horizontal axis. A-Scan is a view of radar video traditionally associated with an oscilloscope display.