Secure your environment with UiPath and CyberArk technologies - Session 1
Monopulse tracking radar
2. Tracking Radar
Measures the coordinate of a target for determining the
target path as well as to predict its future coordinates
Based on the measured coordinated error signal will be
generated
Antenna should be moved based on error signal to
maintain the target within the beam.
Tracking of range, angle, Doppler frequency shift and
radial velocity
Uses pencil beam
3. Angle tracking
Two beams are squinted
Crossover of two beam:
boresight
Boresight always maintained in
the direction of the target
Relative amplitude of two beam
determines how far the target is
from boresight
Also direction in which beam
needs to be repositioned
2 beams in both the coordinate
4. Methods of generating error signal
Conical scan or sequential lobing tracker
Time shares a single beam
Antenna beam is switched between two positions
Simultaneous lobing or monopulse
More than one simultaneous beam is used for tracking
Usually 4 simultaneous beams to perform 2
dimensional tracking
5. MonopulseTracking Radar
Radar in which information concerning the angular
location of the target is obtained by comparing the
signal received in two or more simultaneous beams.
Two offset antenna beams are combined to obtain
both sum and difference signal
This signals are multiplied in a phase sensitive
detector to obtain both magnitude and direction
7. Amplitude comparison monopulse
Two
adjacent antenna
feeds are connected to the
2 input arms of a hybrid
junction
Sum and difference signal
Difference
channel
produce error voltage
appro proportional to the
angular deviation of the
target from the boresight
8. Amplitude comparison monopulse
By comparing the phase of sum and difference signal
direction of angle error is found
Depending on these information's the servo meter will
drive the antenna back to the target
Phase sensitive detector is used to compare the phase
of two signals
11. Monopulse in two angle coordinate
All four feeds are used to generate sum pattern
i.e A+B+C+D
Azimuth difference channel: (A+B) – (C+D)
Elevation difference channel: (B+D) – (A+C)
Two angle errors
Elevation angle error : o/p of phase comparison b/w
sum channel and Elevation difference channel
Azimuth angle error : o/p of phase comparison b/w
sum channel and Azimuth difference channel
12. Phase comparison monopulse
Instead of comparing the amplitude of the echoes
from two squinted beams , the angle of arrival from a
target is determined by comparing the phase
difference between two signals
Uses two separate beams from two separate antenna
looking in same direction
13. Phase comparison monopulse
An echo on boresight will arrive
at the two antennas at the same
time and therefore the phase
difference will be zero
An echo from a target at an angle
q to boresight will arrive at one
antenna later than the other due
to the extra distance it travels.
14. Phase comparison monopulse
Extra distance travelled
by one echo w.r.t other
is given by
Or expressed as phase
difference
Phase detector is used
to find the angle error
16. Comparison
Amplitude-comparison
Phase comparioson
Has high SNR
Grating effect : high
Two feeds at the focus of
single antenna
Squinted beams used
sidelobes are produced in the
sum pattern resulting in
angle measurement
ambiguities
two separate antenna are
used
Beams are not squinted but
look in same direction