IEEE Aerospace and Electronic Systems Magazine - October 2020 - 20

Feature Article:

DOI. No. 10.1109/MAES.2019.2953763

Principles and Applications of Random FM Radar
Waveform Design
Shannon D. Blunt, University of Kansas
John K. Jakabosky, US Naval Research Laboratory
Charles A. Mohr, Patrick M. McCormick, US Air Force Research Laboratory,
WPAFB
Jonathan W. Owen, Brandon Ravenscroft, University of Kansas
Cenk Sahin, US Air Force Research Laboratory, WPAFB
Garrett D. Zook, L3Harris
Christian C. Jones, University of Kansas
Justin G. Metcalf, The University of Oklahoma
Thomas Higgins, US Naval Research Laboratory

INTRODUCTION
As its name implies, noise radar involves the generation
of noise to serve as the illuminating signal with which to
elicit scattering that is collected and processed by a
suitable radar receiver. Consequently, this noise radar
signal is modulated in both phase and amplitude, thereby
providing intrinsic low probability of intercept (LPI)

Authors' current addresses: Shannon D. Blunt,
Jonathan W. Owen, Brandon Ravenscroft, Christian C.
Jones, Radar Systems and Remote Sensing Lab, University of Kansas, Lawrence, KS 66045, USA (e-mail:
sdblunt@ittc.ku.edu). John K. Jakabosky, Radar Systems and Remote Sensing Lab, University of Kansas,
Lawrence, KS 66045 USA, USARadar Division, US
Naval Research Laboratory, Washington, DC 20375
USA USA. Charles A. Mohr, Radar Systems and
Remote Sensing Lab, University of Kansas, Lawrence,
KS 66045 USA, USASensors Directorate, US Air Force
Research Laboratory, WPAFB, OH 45433, USA USA.
Patrick M. McCormick, Cenk Sahin, Sensors Directorate, US Air Force Research Laboratory, WPAFB, OH
45433, USA USA. Garrett D. Zook, L3-Harris, Plano,
TX 75074, USA USA. Justin G. Metcalf, University of
Oklahoma, Norman, OK 73019, USA USA Thomas
Higgins, Radar Division, US Naval Research Laboratory, Washington, DC 20375, USA USA.
Manuscript received September 5, 2019; accepted
October 24, 2019, and ready for publication November
13, 2019.
Review handled by C. Wasserzier.
0885-8985/19/$26.00 ß 2019 IEEE
20

characteristics, though the presence of amplitude modulation does impose a linearity requirement on transmitter
amplification that may preclude noise radar from applications where high power is necessary.
However, there is a special case of noise radar in which
the random nature is restricted to frequency modulation
(FM). While the above LPI attribute may no longer apply,
FM noise waveforms possess a constant amplitude continuous structure that is well suited for high power applications.
The purpose of this article is to familiarize the reader with
this particular type of waveform, introduce some of the
ways that FM noise signals can be generated, discuss the
inherent tradeoffs that arise, and survey some of the emerging applications being facilitated by random FM.
The earliest determinable efforts involving the use of
random FM for radar can be traced to a U.S. Navy patent
application filed in 1956 by Whiteley and Adrian [1],
although the patent was not actually issued until 1980.
Then beginning in 1984, Liu Guosui led a group at Nanjing University of Science and Technology to investigate
the implementation and analysis of radar signals in which
frequency is modulated by white noise [2]. Further theoretical analysis subsequently followed, first by Axelsson
[3], and more recently by Pralon et al. [4], that established
the closed-form expressions for peak-to-sidelobe level
ratio, pulse compression gain, range resolution, etc., under
the assumption that the modulating random process is
Gaussian and wide sense stationary.
In [5], Jakabosky et al. took the position that an arbitrary
random FM initialization for a given pulsed waveform (or
continuous-wave (CW) segment) could be optimized

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