Aerospace and Electronic Systems Magazine January 2018 - 24

Feature Article:

DOI. No. 10.1109/MAES.2017.160198

Detection of Supersonic Rockets Using Passive Bistatic Radar
Mateusz Malanowski, Krzysztof Borowiec, Stanislaw Rzewuski, Krzysztof Kulpa,
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland

INTRODUCTION
The history of rockets starts in antiquity, and has continued through
to modern times. The modern rocket era started before World War II
(WWII), when amateur rocket engineers were building and launching their rockets. During WWII rocket technology was closely associated with weapon development, with the famous V2 rocket as the
most notable example. After the war, rockets were of major importance to space exploration programs [1]. Interest in rocket technology is still high, including among students and amateur engineers.
The focus of this article is on the problem of the detection and
tracking of amateur experimental rockets. After launch, information
on rocket's trajectory is obviously very desirable as it allows for the
verification of parameters of propulsion and guidance systems. The
rocket itself can be equipped with measurement systems based on a
global navigation satellite system and/or inertial navigation system.
These, however, do not solve all the problems. The measurement
equipment onboard the rocket is prone to damage and failures due
to the extreme operating conditions (such as great acceleration).
Moreover, if the data is not sent to the ground station during the
flight, but stored onboard, the rocket has to be located after landing
to download the data. This is not always possible, as the rocket's
landing position may be difficult to estimate. For these reasons, additional sensor for measuring the rocket trajectory is desirable.
The sensor should be external to the rocket, to make sure that is
not prone to damage in case of rocket failure. It should also be inexpensive, as research is often conducted by enthusiasts without large
budgets. The sensor should provide accurate measurements of position, velocity and acceleration, possibly in three-dimensional (3D)
space, with a high refresh rate in the order of several updates per second, as the parameters of the rocket change very quickly. Moreover,
no additional permits should be required for the operation of the sensor, such as those associated with emission of electromagnetic energy.
Passive bistatic radar (PBR) seems to be a perfect candidate
which fulfills these requirements. The PBR, or Passive Coherent
Location (PCL) system, is a type of radar that uses non-cooperative transmitters, such as radio or television transmitters, for target
illumination [2]- [5]. Such a system is cheap, as it is not equipped
Authors' current address: Warsaw University of Technology,
Institute of Electronic Systems, Nowowiejska 15/19, Warsaw,
00-665 Poland, E-mail: (M.Malanowski@elka.pw.edu.pl).
Manuscript received September 14, 2016, revised January 3,
2017, and ready for publication March 1, 2017.
Review handled by D. O'Hagan.
0885/8985/17/$26.00 © 2018 IEEE
24

with a transmitter and can be constructed with the use of universal
radio receivers and a general purpose personal computer. As the
system is passive, no permit is required to operate it. Depending
on the transmitter type used and geometry of the scene, accuracy
in the order of meters in 3D can be obtained. PBR provides high
data refresh rate, typically 0.1-1 s. Moreover, simultaneous unambiguous range and velocity measurements are possible with PBR,
which are problematic in classical active pulse radars [6].
The use of PBR for rocket detection raises, however, some
questions. The observed target is highly maneuverable-the rocket
can be very fast (>Mach 1) and can reach great acceleration values
(hundreds of m/s2). This has to be taken into consideration during signal processing. The rocket also has low radar cross-section
(RCS), which can limit radar's detection range. Also, target illumination by the transmitter has to be considered, as transmitters
usually used for PBR, such as radio or television, are designed to
illuminate receivers on the ground and not in the airspace.
In this article, the analysis of using passive radar for the detection
and tracking of rockets is considered. The analysis is verified with
real data, where an experimental rocket was tracked using Digital
Television Broadcasting-Terrestrial (DVB-T)-based passive radar.

PASSIVE RADAR PRINCIPLES
Passive radar is usually equipped with two antennas providing signals for the reference channel and surveillance channel [7]. The
echo signal will be delayed with respect to the reference signal by
R/c, where R is the bistatic range defined as:
R = R1 + R2 − Rb ,

(1)

where R1 is the transmitter-target range, R2 is the target-receiver
range, and Rb is the transmitter-receiver range (see Figure 1). The
echo signal will also be Doppler shifted with respect to the reference signal by V/λ, where V is the bistatic velocity defined as the
derivative of bistatic range:

V

dR
dt

(2)

and λ is the signal wavelength.
Signals from two channels are then processed using the so
called crossambiguity function defined as [3]:
( R ,V )



IEEE A&E SYSTEMS MAGAZINE

T /2

R

 2 
xe (t )ꞏxr*  t    exp   j
Vt dt ,
c
 



T / 2



(3)

JANUARY 2018

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