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Create blind velocity map for pulsed radar

Since R2023a


    BVM = blindvelocitymap(V,PRF,fc,vmin) creates a blind velocity map BVM for a monostatic pulse-Doppler radar for velocities V. The radar transmits at pulse repetition frequencies PRF. fc represents the radar operating frequency and vmin specifies the minimum detectable velocity of the radar.

    BVM = blindvelocitymap(V,PRF,fc,vmin,obstr) also specifies obstructions obstr in velocity.


    [BVM,U] = blindvelocitymap(___) also returns the proportion of visible velocities U.

    blindvelocitymap(___) plots the blind velocity map.


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    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.


    Input Arguments

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    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.

    Example: [4000,4500,6000]

    Data Types: double

    Pulse repetition frequencies, specified as a length-N vector of positive values. Units are in Hz.

    Example: [10000,15000]

    Data Types: double

    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 value, fc is a length-N vector where N is the size of PRF.

    Example: 3e9

    Data Types: double

    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 from -vmin to +vmin for all PRF values.

    • If the radar has the same minimum detectable velocity for all PRFs, vmin is a scalar and the size of the blind zone is constant for all PRF values.

    • If the minimum detectable velocity varies with PRF, vmin is a length-N vector and the size of the blind zone is different for each PRF.

    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 meters/sec.

    Example: 15.0

    Data Types: double

    Obstructions in velocity, specified as a Q-by-2 matrix of positive values. The qth row specifies a velocity obstruction in the form [vstartq,vstopq] where vstartq is the start velocity of the qTh obstruction and vstopq is the stop velocity of the qth obstruction, such that vstopqvstartq. 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. Entries in BVM that correspond to the obstructed velocities are set to a logical one (true). Units are in meters/second.

    Example: [30000;31000]

    Data Types: double

    Output Arguments

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    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 V. The nth column of BVM corresponds to the jth pulse repetition frequency in PRF. If the jth velocity in V is visible to the radar at the nth PRF, BVM(j,n) is a logical zero (false), otherwise BVM(j,n) is a logical one (true).

    Data Types: logical

    Proportion of visible velocities, returned as a length-N real-valued vector. This argument indicates for each pulse repetition frequency in PRF what proportion of velocities in V is visible.

    Extended Capabilities

    C/C++ Code Generation
    Generate C and C++ code using MATLAB® Coder™.

    Version History

    Introduced in R2023a