simclutter.m

阵列信号处理的工具箱

function clutterSig3D = simclutter2(clutter, transmitGain, steeringMatrix, ...
                                   lambda, sampleTime, noPulses, noRangeBins,...
                                   propSpeed, pri, h, platVel);

%SIMCLUTTER is the core simulating engine for simulating clutter sources.
%
%Synopsis:
%  clutterSig3D = simclutter(clutter, transmitGain, steeringMatrix, ...
%                            lambda, sampleTime, noPulses, noRangeBins,...
%                            propSpeed, pri);
%
%Description:
%  Simulates radarsignals and stores the data in a 3D matrix
%  ( Number Pulses x Number Of RangeBins x Number Of Channels)
%
%  Clutter is defined by a power spectral density function (PSD) which
%  describes the power of the clutter at a certain frequency. To simulate
%  clutter for a specific direction and range you simply simulate complex
%  gaussian noise and multiply this noise with the PSD and then performe
%  an inverse FFT. These steps simulates a clutter signal in the pulse
%  domain. There are some considerations though. The PSD has to be sampled
%  and it is thus important not to undersample this function. If a
%  specific timeresolution is wanted (after the inverse FFT) a correct
%  frequency span must be chosen. I.e. if the wanted timeresolution is
%  equal to pri then the total frequency span that the PSD is to be
%  sampled over must be 1/pri! Since the PSD describes how the clutter
%  source are moving the PSD must be sampled symetrically round the
%  frequency zero. In the direction domain consideration to the
%  transmitting antenna patern has to be taken. The ground is divided into
%  small so called clutterpatches from which clutter is radiated. The
%  power of the clutter at each clutterpatch is determined by the
%  transmitting antenna pattern and the area of the patch and also by the
%  distance to the patch. So far no considerations to patcharea nor
%  the distance to the patch is taken. the input variable power is used to
%  determine the power of the strongest clutterpatch. The clutterpatch
%  that illuminates most is the one where the transmitting antenna pattern
%  has its maximum. The width of the clutterpatches are determined by the
%  stepsize in the variable "clutter.DOAs", i.e. the directions to the
%  patches. This stepsize should not be much larger then a third of the
%  beamwith of the transmitting antenna, since this is the sampling angle
%  of the transmitting antenna pattern.
%
%  This function is called upon by simradarsig and should be
%  hidden from the everyday user.
%
%Input:
%  clutter (ClutterDefT)      : Definition of clutter parameters.
%  transmitGain (RealVectorT) : Sampled gain(theta) from transmitting antenna
%  steeringMatrix (CxMatrixT) : Steering matrix calculated for all directions
%                               to clutterpatches.
%  lambda (RealScalarT)       : Wavelength [m]
%  sampleTime (RealScalarT)   : Sample period time in transmitter and receiver.
%                               One sampleTime corresponds to one range bin.
%  noPulses (IntScalarT)      : Number of pulese to simulate for.
%  noRangeBins (IntScalarT)   : Number of rangebins for this radarsystem.
%  propSpeed (RealScalarT)    : Speed of light in current medium [m/s].
%  pri (RealScalarT)          : Pulse repetition interval [s].
%  h (RealScalarT)            : Height above ground of radar platform
%  platVel (RealScalarT)      : Speed of Radar platform along array

%
%OutPut:
%  clutterSig3D (CxMatrixT) : 3D matrix with the simulated clutter data.
%                             pulses x rangebins x channels.
%
%--------
%Clutter of type 'MIT-LCE'
%-------------------------
%Description:
%  MIT-LCE is the result of some measurements done by MIT Lincoln
%  Laboratory [3]. These measurements indicate that clutter is
%  exponentially distributed in contrast to the commonly used gaussian
%  shape. The exponential power spectral density of clutter is discribed
%  with some shape parameters depending on wind conditions. See function
%  "defclutter" for a description of the input parameters.
%
%Notations:
%  Data type names are shown in parentheses and they start with a capital
%  letter and end with a capital T. Data type definitions can be found in
%  [1] or by "help dbtdata".
%
%Examples:
%
%Software Quality:
%
%Known Bugs:
%  1) Pulsemodulation is not performed.
%
%  2) No considerations for range distribution is taken. The simulated
%     signal is same for all wanted ranges.
%
%References:
%  [1]: Bj鰎klund S., Rejdemyhr D. Athley F.: "DBT, A MATLAB Toolbox
%       for Radar Signal Processing. Reference Guide",
%       FOA-D--9x-00xxx-408--SE, To be published.
%
%  [2]  Rejdemyhr D.: "En studie av klotters inverkan p