Abstract: A signal processing system for use in pulse-Doppler radar, arranged to receive frequency domain signals for each of a plurality of Doppler bins for each range cell, comprising a data processor arranged successively to threshold each Doppler bin signal under test relative to a local average of signals formed over plural Doppler bins and/or plural ranges adjacent to the Doppler bin under test, using a variable thresholding factor, and using the thresholding result as an indication of the presence of an object of interest; the data processor using a pulse-Doppler constant false alarm rate control process to set and reset the variable thresholding factor using closed loop feedback by counting the indications of presence and incrementing or decrementing the variable thresholding factor for each thresholding result by comparing the frequency of these counts with a predetermined probability of false alarms; whereby the constant false alarm rate thresholding is a function of the range and the Doppler frequency of the

Abstract: A signal processing system for use in pulse-Doppler radar, arranged to receive frequency domain signals for each of a plurality of Doppler bins for each range cell, comprising a data processor arranged successively to threshold each Doppler bin signal under test relative to a local average of signals formed over plural Doppler bins and/or plural ranges adjacent to the Doppler bin under test, using a variable thresholding factor, and using the thresholding result as an indication of the presence of an object of interest; the data processor using a pulse-Doppler constant false alarm rate control process to set and reset the variable thresholding factor using closed loop feedback by counting the indications of presence and incrementing or decrementing the variable thresholding factor for each thresholding result by comparing the frequency of these counts with a predetermined probability of false alarms; whereby the constant false alarm rate thresholding is a function of the range and the Doppler frequency of the

Abstract: An antenna comprises at least one accelerometer capable of monitoring mechanical vibration. Associated signal processing means provides a transfer function which is used to convert signals received from the accelerometer into an error estimate, which can then be subtracted from signals received from the antenna.

Abstract: A scan-to-scan integrator for use in radar apparatus comprises means for defining a search window for use in verifying a candidate detection.