Create blind velocity map for pulsed radar
blindvelocitymap(___) plots the blind velocity
Display Blind Velocity Map
A 10 GHz X-band medium PRF radar has a rejection notch to reject slow moving targets with velocities up to 20 m/s. Plot a blind velocity map for pulse repetition frequencies between 5 kHz and 15 kHz, assuming that velocities from 90 m/s to 115 m/s and from 155 m/s to 165 m/s are obstructed due to clutter.
Set up velocities and PRF.
V = linspace(0,500,1000); PRF = linspace(5e3,15e3,1000);
Set the radar frequency to 10 GHz.
fc = 10e9; % Rejection notch half-width (m/s)
Set the velocity obstructions.
obstructions = [90 115;155 165];
Set the rejection notch half-width to 20 meters/sec.
vmin = 20;
Create the blind velocity map.
V — Velocities
length-J real-valued vector
Radar velocities, specified as a length-J real-valued vector of positive values. The function computes the blind velocity map at these velocities Units are in meters/sec.
PRF — Pulse repetition frequencies
length-N vector of positive values
Pulse repetition frequencies, specified as a length-N vector of positive values. Units are in Hz.
fc — Radar waveform carrier frequency
positive scalar (default) | length-N vector of positive values
Radar waveform carrier frequency, specified as a positive scalar or
length-N vector of positive values. If the radar transmits pulses
at a fixed carrier frequency, the input
fc is a scalar. If the
radar employs frequency diversity using a different carrier frequency for each PRF
fc is a length-N vector where
N is the size of
vmin — Minimum detectable velocity
scalar (default) | length-N real-valued vector
Minimum detectable velocity, specified as a scalar or length-N
real-valued vector. A blind zone due to a non-zero minimum detectable velocity extends
vmin to +
vmin for all
If the radar has the same minimum detectable velocity for all
vminis a scalar and the size of the blind zone is constant for all
If the minimum detectable velocity varies with
vminis a length-N vector and the size of the blind zone is different for each
Due to ambiguities in velocity, blind zones also appear around integer
multiples of the blind speed VB and extend
from VB*i - Vmin to
VB*i + Vmin, where
VB = PRF*c/(2*fc), c is
the signal propagation speed, and i is an integer. The input
vmin can represent the half-width of a rejection notch that is
used to reject main lobe clutter and slow moving targets. Units are in
obstr — Obstructions in velocity
Obstructions in velocity, specified as a Q-by-2 matrix of
positive values. The
qth row specifies a
velocity obstruction in the form
vstartq is the start velocity of the
qTh obstruction and
vstopq is the stop velocity of the
qth obstruction, such that
vstartq. Targets moving with the
specified obstructed velocities or velocities ambiguous to the specified obstructed
velocities are not visible to the radar. Such obstructions can occur due to clutter.
BVM that correspond to the obstructed velocities are set
to a logical one (
true). Units are in meters/second.
BVM — Blind velocity map
J-by-N logical matrix
Blind velocity map, returned as a J-by-N
logical matrix. The
jth row of
BVM represents a velocity cell with the velocity equal to the
jth entry in
nth column of
corresponds to the
jth pulse repetition
PRF. If the
jth velocity in
is visible to the radar at the
(j,n) is a logical zero
is a logical one (
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