Page 536 - Fundamentals of Radar Signal Processing

In some cases the detection probability may still be lower than required. In

this event, the threshold may be lowered, increasing but also increasing .
Additional techniques can then be applied at other stages of the overall system
processing in order to reduce back to an acceptable level. Several options
are discussed in (Nathanson, 1991); their applicability depends on the particular

system involved. If jamming is present, a sidelobe blanker or sidelobe canceller
can be used to further improve the SIR before the detector (assuming more
advanced techniques such as STAP have not already been applied). After the
detector, a clutter map may be used in some systems to reject false alarms due to
fixed clutter discretes or known radio frequency interference (RFI) sources. If
valid targets can be expected to extend over more than one range, azimuth, or
Doppler cell, apparent detections that occupy only a single cell can be rejected

as false alarms after the detector, lowering the system . Finally, an apparent
target can be tracked to make sure it recurs over multiple scans; if it does not, it
is rejected as a false alarm. If it does, its kinematics can be tracked over
multiple scans. If the target track violates reasonable bounds on velocity and
acceleration, it can be assumed to be a false alarm, quite possibly due to the
presence of electronic countermeasures, and the track can be rejected. Thus,

control of the overall system false alarm rate can be spread over virtually all
stages of the system.

References

Albersheim, W. J., “Closed-Form Approximation to Robertson’s Detection
Characteristics,” Proceedings of IEEE, vol. 69, no. 7, p. 839, Jul. 1981.
Barrett, C. R., Jr., “Adaptive Thresholding and Automatic Detection,” Chap. 12
in J. L. Eaves and E. K. Reedy (eds.), Principles of Modern Radar. Van

Nostrand Reinhold, New York, 1987.
Blake, S., “OS-CFAR Theory for Multiple Targets and Nonuniform Clutter,”
IEEE Transactions on Aerospace and Electronic Systems, vol. AES-24,
no. 6, pp. 785–790, Nov. 1988.
Cantrell, P. E., and A. K. Ojha, “Comparison of Generalized Q-function
Algorithms,” IEEE Transactions on Information Theory, vol. IT-33, no.
4, pp. 591–596, Jul. 1987.

Conte, E., and M. Lops, “Clutter-Map CFAR Detection for Range-Spread
Targets in Non-Gaussian Clutter, Part I: System Design,” IEEE
Transactions on Aerospace and Electronic Systems, vol. AES-33, no. 2,
pp. 432–442, Apr. 1997.
Di Vito, A., and G. Moretti, “Probability of False Alarm in CA-CFAR Device
Downstream From Linear-law Detector,” Electronics Letters, vol. 25, no.

5, pp. 1692–1693, Dec. 1989.
DiFranco, J. V., and W. L. Rubin, Radar Detection. Artech House, Dedham,