Monopulse Estimator

Estimate target direction from sum and difference channels

Since R2018b

Libraries:
Phased Array System Toolbox / Direction of Arrival

Description

The Monopulse Estimator estimates the direction of arrival of a narrowband signal based on an initial guess by applying amplitude monopulse processing on sum and difference channel signals received by an array. You can create these channels using the Monopulse Feed block.

Ports

Input

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Sum-channel signal, specified as a complex-valued N-by-1 column vector. N is the number of snapshots in the signal.

Data Types: `double`
Complex Number Support: Yes

Azimuth difference-channel signal, specified as a complex-valued N-by-1 column vector. N is the number of snapshots in the signal.

Data Types: `double`
Complex Number Support: Yes

Elevation difference-channel signal, specified as a complex-valued N-by-1 column vector. N is the number of snapshots in the signal.

Dependencies

To enable this output port, set the Monopulse coverage parameter to `3D`.

Data Types: `double`
Complex Number Support: Yes

Array steering direction, specified as a scalar or real-valued 2-by-1 column vector.

• When you set the Monopulse coverage parameter to `Azimuth`, the steering direction is a scalar and represents the azimuth steering angle.

• When you set the Monopulse coverage parameter to `3D`, the steering direction vector has the form `[azimuthAngle; elevationAngle]`, where `azimuthAngle` is the azimuth steering angle, and `elevationAngle` is the elevation steering angle.

Units are in degrees. Azimuth angles lie between –180° and 180°, inclusive, and elevation angles lie between –90° and 90°, inclusive.

Example: `[40;10]`

Data Types: `double`

Output

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Estimated azimuth direction of target, returned as a real-valued 1-by-N. The vector elements contain the estimated target direction azimuth angle at each signal snapshot. Units are in degrees.

Dependencies

To enable this output port, set the Monopulse coverage to `Azimuth` and the OutputFormat to `Angle`.

Data Types: `double`

Estimated offset of azimuth direction of target, returned as a real-valued 1-by-N vector. The vector elements contain the offset of the estimated target direction azimuth angle from the azimuth steering direction at each signal snapshot. Units are in degrees.

Dependencies

To enable this output port, set the Monopulse coverage to `Azimuth` and the OutputFormat to ```Angle offset```.

Data Types: `double`

Estimated direction of target, returned as a real-valued 2-by-N matrix. Each column contains the estimated target direction in the form ```[azimuthAngle; elevationAngle]``` ,where `azimuthAngle` is the estimated azimuth angle, and `elevationAngle` is estimated elevation angle. Units are in degrees.

Dependencies

To enable this output port, set the Monopulse coverage to `3D` and the OutputFormat to `Angle`.

Data Types: `double`

Estimated offset of direction of target, returned as a real-valued 2-by-N matrix. The offset is the difference between the target direction and the steering vector. Each column contains the estimated offset of the target direction in the form `[dazimuthAngle; delevationAngle]`, where `dazimuthAngle` is the estimated azimuth angle offset, and `delevationAngle` is estimated elevation angle offset. Units are in degrees.

Dependencies

To enable this output port, set the Monopulse coverage to `3D` and the OutputFormat to ```Angle offset```.

Data Types: `double`

Ratio of sum and azimuth difference channels, returned as a real-valued 1-by-N vector. The elements contain the ratio of the sum to azimuth difference channel at each signal snapshot.

Dependencies

To enable this output port, set the Monopulse coverage to `Azimuth` and select the Output sum difference ratio check box.

Data Types: `double`

Ratio of sum and azimuth and elevation difference channels, returned as a real-valued 2-by-N matrix. The elements of the first row contain the ratio of the sum to azimuth difference channel at each signal snapshot. The elements of the second row contain the ratio of the sum to elevation difference channel at each signal snapshot.

Dependencies

To enable this output port, set the Monopulse coverage to `3D` and select the Output sum difference ratio check box.

Data Types: `double`

Parameters

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Main Tab

Signal propagation speed, specified as a real-valued positive scalar. The default value of the speed of light is the value returned by `physconst('LightSpeed')`. Units are in meters per second.

Example: `3e8`

Data Types: `double`

System operating frequency, specified as a positive scalar. Units are in Hz.

Monopulse coverage directions, specified as `3D` or `Azimuth`. When you set this parameter to `3D`, the monopulse estimator uses the sum channel and both azimuth and elevation difference channels. When you set this parameter to `Azimuth`, the monopulse estimator uses the sum channel and the azimuth difference channel.

Squint angle, specified as a scalar or real-valued 2-by-1 vector. The squint angle is the separation angle between the sum beam and the beams along the azimuth and elevation directions.

• When you set the `Monopulse coverage` parameter to `Azimuth`, set the ```Squint angle``` parameter to a scalar.

• When you set the `Monopulse coverage` parameter to `3D`, you can specify the squint angle as either a scalar or vector. If you set the `Squint angle` parameter to a scalar, the squint angle is the same along both the azimuth and elevation directions. If you set the `Squint angle` parameter to a 2-by-1 vector, its elements specify the squint angle along the azimuth and elevation directions.

Example: `[20;5]`

Format of direction output, specified `Angle` or `Angle offset`. When you set this parameter to `Angle`, the output port is labeled `AzEl` or `Az` and is the actual direction of the target. When you set this property to ```Angle offset```, the output port is labeled `dAzEl` or `dAz` and is the angle offset of the target from the array steering direction.

Select this check box to output the ratio of the sum and difference channels in the azimuth and elevation directions. When you set the Monopulse coverage to `Azimuth`, the block outputs the sum-azimuth difference ratio using the `AzRatio` port. When you set the Monopulse coverage to `3D`, the block outputs the sum-azimuth difference and sum-elevation difference channels ratio using the `AzElRatio` port.

Click this button to create a Monopulse Feed block based on the parameters in this block.

Block simulation, specified as `Interpreted Execution` or `Code Generation`. If you want your block to use the MATLAB® interpreter, choose `Interpreted Execution`. If you want your block to run as compiled code, choose ```Code Generation```. Compiled code requires time to compile but usually runs faster.

Interpreted execution is useful when you are developing and tuning a model. The block runs the underlying System object™ in MATLAB. You can change and execute your model quickly. When you are satisfied with your results, you can then run the block using ```Code Generation```. Long simulations run faster with generated code than in interpreted execution. You can run repeated executions without recompiling, but if you change any block parameters, then the block automatically recompiles before execution.

This table shows how the Simulate using parameter affects the overall simulation behavior.

When the Simulink® model is in `Accelerator` mode, the block mode specified using Simulate using overrides the simulation mode.

Acceleration Modes

 Block Simulation Simulation Behavior `Normal` `Accelerator` `Rapid Accelerator` `Interpreted Execution` The block executes using the MATLAB interpreter. The block executes using the MATLAB interpreter. Creates a standalone executable from the model. `Code Generation` The block is compiled. All blocks in the model are compiled.

Programmatic Use

 Block Parameter:`SimulateUsing` Type:enum Values:```Interpreted Execution```, `Code Generation` Default:```Interpreted Execution```
Sensor Arrays Tab

Method to specify array, specified as `Array (no subarrays)` or `MATLAB expression`.

• `Array (no subarrays)` — use the block parameters to specify the array.

• `Partitioned array` — use the block parameters to specify the array.

• `Replicated subarray` — use the block parameters to specify the array.

• `MATLAB expression` — create the array using a MATLAB expression.

MATLAB expression used to create an array, specified as a valid Phased Array System Toolbox array System object.

Example: `phased.URA('Size',[5,3])`

Dependencies

To enable this parameter, set Specify sensor array as to `MATLAB expression`.

Element Parameters

Antenna or microphone type, specified as one of the following:

• `Isotropic Antenna`

• `Cosine Antenna`

• `Custom Antenna`

• `Omni Microphone`

• `Custom Microphone`

Specify the operating frequency range of the antenna or microphone element as a 1-by-2 row vector in the form `[LowerBound,UpperBound]`. The element has no response outside this frequency range. Frequency units are in Hz.

Dependencies

To enable this parameter, set Element type to `Isotropic Antenna`, `Cosine Antenna`, or `Omni Microphone`.

Specify the frequencies at which to set antenna and microphone frequency responses as a 1-by-L row vector of increasing real values. The antenna or microphone element has no response outside the frequency range specified by the minimum and maximum elements of this vector. Frequency units are in Hz.

Dependencies

To enable this parameter, set Element type to ```Custom Antenna``` or `Custom Microphone`. Use Frequency responses (dB) to set the responses at these frequencies.

Select this check box to baffle the back response of the element. When back baffled, the responses at all azimuth angles beyond ±90° from broadside are set to zero. The broadside direction is defined as 0° azimuth angle and 0° elevation angle.

Dependencies

To enable this check box, set Element type to `Isotropic Antenna` or `Omni Microphone`.

Specify the exponents of the cosine pattern as a nonnegative scalar or a real-valued 1-by-2 matrix of nonnegative values. When Exponent of cosine pattern is a 1-by-2 vector, the first element is the exponent in the azimuth direction and the second element is the exponent in the elevation direction. When you set this parameter to a scalar, both the azimuth direction and elevation direction cosine patterns are raised to the same power.

Dependencies

To enable this parameter, set Element type to ```Cosine Antenna```.

Frequency response of a custom antenna or custom microphone for the frequencies defined by the Operating frequency vector (Hz) parameter. The dimensions of Frequency responses (dB) must match the dimensions of the vector specified by the Operating frequency vector (Hz) parameter.

Dependencies

To enable this parameter, set Element type to `Custom Antenna` or ```Custom Microphone```.

Coordinate system of custom antenna pattern, specified `az-el` or `phi-theta`. When you specify `az-el`, use the Azimuth angles (deg) and Elevations angles (deg) parameters to specify the coordinates of the pattern points. When you specify `phi-theta`, use the Phi angles (deg) and Theta angles (deg) parameters to specify the coordinates of the pattern points.

Dependencies

To enable this parameter, set Element type to `Custom Antenna`.

Specify the azimuth angles at which to calculate the antenna radiation pattern as a 1-by-P row vector. P must be greater than 2. Azimuth angles must lie between –180° and 180°, inclusive, and be in strictly increasing order.

Dependencies

To enable this parameter, set the Element type parameter to `Custom Antenna` and the Input Pattern Coordinate System parameter to `az-el`.

Specify the elevation angles at which to compute the radiation pattern as a 1-by-Q vector. Q must be greater than 2. Angle units are in degrees. Elevation angles must lie between –90° and 90°, inclusive, and be in strictly increasing order.

Dependencies

To enable this parameter, set the Element type parameter to `Custom Antenna` and the Input Pattern Coordinate System parameter to `az-el`.

Phi angles of points at which to specify the antenna radiation pattern, specify as a real-valued 1-by-P row vector. P must be greater than 2. Angle units are in degrees. Phi angles must lie between 0° and 360° and be in strictly increasing order.

Dependencies

To enable this parameter, set the Element type parameter to `Custom Antenna` and the Input Pattern Coordinate System parameter to `phi-theta`.

Theta angles of points at which to specify the antenna radiation pattern, specify as a real-valued 1-by-Q row vector. Q must be greater than 2. Angle units are in degrees. Theta angles must lie between 0° and 360° and be in strictly increasing order.

Dependencies

To enable this parameter, set the Element type parameter to `Custom Antenna` and the Input Pattern Coordinate System parameter to `phi-theta`.

Magnitude of the combined antenna radiation pattern, specified as a Q-by-P matrix or a Q-by-P-by-L array.

• When the Input Pattern Coordinate System parameter is set to `az-el`, Q equals the length of the vector specified by the Elevation angles (deg) parameter and P equals the length of the vector specified by the Azimuth angles (deg) parameter.

• When the Input Pattern Coordinate System parameter is set to `phi-theta`, Q equals the length of the vector specified by the Theta Angles (deg) parameter and P equals the length of the vector specified by the Phi Angles (deg) parameter.

The quantity L equals the length of the Operating frequency vector (Hz).

• If this parameter is a Q-by-P matrix, the same pattern is applied to all frequencies specified in the Operating frequency vector (Hz) parameter.

• If the value is a Q-by-P-by-L array, each Q-by-P page of the array specifies a pattern for the corresponding frequency specified in the Operating frequency vector (Hz) parameter.

Dependencies

To enable this parameter, set Element type to `Custom Antenna`.

Phase of the combined antenna radiation pattern, specified as a Q-by-P matrix or a Q-by-P-by-L array.

• When the Input Pattern Coordinate System parameter is set to `az-el`, Q equals the length of the vector specified by the Elevation angles (deg) parameter and P equals the length of the vector specified by the Azimuth angles (deg) parameter.

• When the Input Pattern Coordinate System parameter is set to `phi-theta`, Q equals the length of the vector specified by the Theta Angles (deg) parameter and P equals the length of the vector specified by the Phi Angles (deg) parameter.

The quantity L equals the length of the Operating frequency vector (Hz).

• If this parameter is a Q-by-P matrix, the same pattern is applied to all frequencies specified in the Operating frequency vector (Hz) parameter.

• If the value is a Q-by-P-by-L array, each Q-by-P page of the array specifies a pattern for the corresponding frequency specified in the Operating frequency vector (

Dependencies

To enable this parameter, set Element type to `Custom Antenna`.

Select this check box to rotate the antenna element pattern to align with the array normal. When not selected, the element pattern is not rotated.

When the antenna is used in an antenna array and the Input Pattern Coordinate System parameter is `az-el`, selecting this check box rotates the pattern so that the x-axis of the element coordinate system points along the array normal. Not selecting uses the element pattern without the rotation.

When the antenna is used in an antenna array and Input Pattern Coordinate System is set to `phi-theta`, selecting this check box rotates the pattern so that the z-axis of the element coordinate system points along the array normal.

Use the parameter in conjunction with the Array normal parameter of the `URA` and `UCA` arrays.

Dependencies

To enable this parameter, set Element type to `Custom Antenna`.

Polar pattern microphone response frequencies, specified as a real scalar, or a real-valued, 1-by-L vector. The response frequencies lie within the frequency range specified by the Operating frequency vector (Hz) vector.

Dependencies

To enable this parameter, set Element type set to `Custom Microphone`.

Specify the polar pattern response angles, as a 1-by-P vector. The angles are measured from the central pickup axis of the microphone and must be between –180° and 180°, inclusive.

Dependencies

To enable this parameter, set Element type to `Custom Microphone`.

Specify the magnitude of the custom microphone element polar patterns as an L-by-P matrix. L is the number of frequencies specified in Polar pattern frequencies (Hz). P is the number of angles specified in Polar pattern angles (deg). Each row of the matrix represents the magnitude of the polar pattern measured at the corresponding frequency specified in Polar pattern frequencies (Hz) and all angles specified in Polar pattern angles (deg). The pattern is measured in the azimuth plane. In the azimuth plane, the elevation angle is 0° and the central pickup axis is 0° degrees azimuth and 0° degrees elevation. The polar pattern is symmetric around the central axis. You can construct the microphone response pattern in 3-D space from the polar pattern.

Dependencies

To enable this parameter, set Element type to `Custom Microphone`.

Array Parameters

Array geometry, specified as one of

• `ULA` — Uniform linear array

• `URA` — Uniform rectangular array

• `UCA` — Uniform circular array

• `Conformal Array` — arbitrary element positions

The number of array elements for ULA or UCA arrays, specified as an integer greater than or equal to 2.

When you set Specify sensor array as to ```Replicated subarray```, this parameter applies to each subarray.

Dependencies

To enable this parameter, set Geometry to `ULA` or `UCA`.

• ULA — specify the spacing between two adjacent elements in the array as a positive scalar.

• URA — specify the spacing as a positive scalar or a 1-by-2 vector of positive values. If Element spacing (m) is a scalar, the row and column spacings are equal. If Element spacing (m) is a vector, the vector has the form `[SpacingBetweenArrayRows,SpacingBetweenArrayColumns]`.

• When you set Specify sensor array as to `Replicated subarray`, this parameter applies to each subarray.

Dependencies

To enable this parameter, set Geometry to `ULA` or `URA`.

Linear axis direction of ULA, specified as `y`, `x`, or `z`. All ULA array elements are uniformly spaced along this axis in the local array coordinate system.

Dependencies

• To enable this parameter, set Geometry to `ULA`.

• This parameter is also enabled when the block only supports ULA arrays.

Dimensions of a URA array, specified as a positive integer or 1-by-2 vector of positive integers.

• If Array size is a 1-by-2 vector, the vector has the form `[NumberOfArrayRows,NumberOfArrayColumns]`.

• If Array size is an integer, the array has the same number of rows and columns.

• When you set Specify sensor array as to `Replicated subarray`, this parameter applies to each subarray.

For a URA, array elements are indexed from top to bottom along the leftmost column, and then continue to the next columns from left to right. In this figure, the Array size value of `[3,2]` creates an array having three rows and two columns.

Dependencies

To enable this parameter, set Geometry to `URA`.

Lattice of URA element positions, specified as `Rectangular` or `Triangular`.

• `Rectangular` — Aligns all the elements in row and column directions.

• `Triangular` — Shifts the even-row elements of a rectangular lattice toward the positive row-axis direction. The displacement is one-half the element spacing along the row dimension.

Dependencies

To enable this parameter, set Geometry to `URA`.

Array normal direction, specified as `x`, `y`, or `z`.

Elements of planar arrays lie in a plane orthogonal to the selected array normal direction. Element boresight directions point along the array normal direction.

Array Normal Parameter ValueElement Positions and Boresight Directions
`x`Array elements lie in the yz-plane. All element boresight vectors point along the x-axis.
`y`Array elements lie in the zx-plane. All element boresight vectors point along the y-axis.
`z`Array elements lie in the xy-plane. All element boresight vectors point along the z-axis.

Dependencies

To enable this parameter, set Geometry to `URA` or `UCA`.

Radius of UCA array, specified as a positive scalar.

Dependencies

To enable this parameter, set Geometry to `UCA`.

Positions of the elements in a conformal array, specified as a 3-by-N matrix of real values, where N is the number of elements in the conformal array. Each column of this matrix represents the position `[x;y;z]`of an array element in the array local coordinate system. The origin of the local coordinate system is (0,0,0). Units are in meters.

When you set Specify sensor array as to ```Replicated subarray```, this parameter applies to each subarray.

Dependencies

To enable this parameter set Geometry to ```Conformal Array```.

Direction of element normal vectors in a conformal array, specified as a 2-by-1 column vector or a 2-by-N matrix. N indicates the number of elements in the array. For a matrix, each column specifies the normal direction of the corresponding element in the form `[azimuth;elevation]` with respect to the local coordinate system. The local coordinate system aligns the positive x-axis with the direction normal to the conformal array. If the parameter value is a 2-by-1 column vector, the same pointing direction is used for all array elements.

When you set Specify sensor array as to ```Replicated subarray```, this parameter applies to each subarray.

You can use the Element positions (m) and Element normals (deg) parameters to represent any arrangement in which pairs of elements differ by certain transformations. The transformations can combine translation, azimuth rotation, and elevation rotation. However, you cannot use transformations that require rotation about the normal direction.

Dependencies

To enable this parameter, set Geometry to `Conformal Array`.

Element tapering, specified as a complex-valued scalar or a complex-valued 1-by-N row vector. In this vector, N represents the number of elements in the array.

Also known as element weights, tapers multiply the array element responses. Tapers modify both amplitude and phase of the response to reduce side lobes or steer the main response axis.

If Taper is a scalar, the same weight is applied to each element. If Taper is a vector, a weight from the vector is applied to the corresponding sensor element. The number of weights must match the number of elements of the array.

When you set Specify sensor array as to `Replicated subarray`, this parameter applies to each subarray.

Specify the subarray selection as an M-by-N matrix. M is the number of subarrays and N is the total number of elements in the array. Each row of the matrix represents a subarray and each entry in the row indicates when an element belongs to the subarray. When the entry is zero, the element does not belong the subarray. A nonzero entry represents a complex-valued weight applied to the corresponding element. Each row must contain at least one nonzero entry.

The phase center of each subarray lies at the subarray geometric center. The subarray geometric center depends on the Subarray definition matrix and Geometry parameters.

Dependencies

To enable this parameter, set Specify sensor array as to `Partitioned array`.

Subarray steering method, specified as one of

• `None`

• `Phase`

• `Time`

• `Custom`

Selecting `Phase` or `Time` opens the `Steer` input port on the Narrowband Receive Array, Narrowband Transmit Array, Wideband Receive Array, Wideband Transmit Array blocks, Constant Gamma Clutter, and GPU Constant Gamma Clutter blocks.

Selecting `Custom` opens the `WS` input port on the Narrowband Receive Array, Narrowband Transmit Array, Wideband Receive Array, Wideband Transmit Array blocks, Constant Gamma Clutter, and GPU Constant Gamma Clutter blocks.

Dependencies

To enable this parameter, set Specify sensor array as to `Partitioned array` or ```Replicated subarray```.

Operating frequency of subarray steering phase shifters, specified as a positive real-valued scalar. Units are Hz.

Dependencies

To enable this parameter, set Sensor array to `Partitioned array` or `Replicated subarray` and set Subarray steering method to `Phase`.

Subarray steering phase shift quantization bits, specified as a non-negative integer. A value of zero indicates that no quantization is performed.

Dependencies

To enable this parameter, set Sensor array to `Partitioned array` or `Replicated subarray` and set Subarray steering method to `Phase`.

Specify the layout of replicated subarrays as `Rectangular` or `Custom`.

• When you set this parameter to `Rectangular`, use the Grid size and Grid spacing parameters to place the subarrays.

• When you set this parameter to `Custom`, use the Subarray positions (m) and Subarray normals parameters to place the subarrays.

Dependencies

To enable this parameter, set Sensor array to `Replicated subarray`

Rectangular subarray grid size, specified as a single positive integer, or a 1-by-2 row vector of positive integers.

If Grid size is an integer scalar, the array has an equal number of subarrays in each row and column. If Grid size is a 1-by-2 vector of the form `[NumberOfRows, NumberOfColumns]`, the first entry is the number of subarrays along each column. The second entry is the number of subarrays in each row. A row is along the local y-axis, and a column is along the local z-axis. The figure here shows how you can replicate a 3-by-2 URA subarray using a Grid size of `[1,2]`.

Dependencies

To enable this parameter, set Sensor array to ```Replicated subarray``` and Subarrays layout to `Rectangular`.

The rectangular grid spacing of subarrays, specified as a positive, real-valued scalar, a 1-by-2 row vector of positive, real-values, or `Auto`. Units are in meters.

• If Grid spacing is a scalar, the spacing along the row and the spacing along the column is the same.

• If Grid spacing is a 1-by-2 row vector, the vector has the form `[SpacingBetweenRows,SpacingBetweenColumn]`. The first entry specifies the spacing between rows along a column. The second entry specifies the spacing between columns along a row.

• If Grid spacing is set to `Auto`, replication preserves the element spacing of the subarray for both rows and columns while building the full array. This option is available only when you specify Geometry as `ULA` or `URA`.

Dependencies

To enable this parameter, set Sensor array to `Replicated subarray` and Subarrays layout to `Rectangular`.

Positions of the subarrays in the custom grid, specified as a real 3-by-N matrix, where N is the number of subarrays in the array. Each column of the matrix represents the position of a single subarray in the array local coordinate system. The coordinates are expressed in the form `[x; y; z]`. Units are in meters.

Dependencies

To enable this parameter, set Sensor array to `Replicated subarray` and Subarrays layout to `Custom`.

Specify the normal directions of the subarrays in the array. This parameter value is a 2-by-N matrix, where N is the number of subarrays in the array. Each column of the matrix specifies the normal direction of the corresponding subarray, in the form `[azimuth;elevation]`. Angle units are in degrees. Angles are defined with respect to the local coordinate system.

You can use the Subarray positions and Subarray normals parameters to represent any arrangement in which pairs of subarrays differ by certain transformations. The transformations can combine translation, azimuth rotation, and elevation rotation. However, you cannot use transformations that require rotation about the normal.

Dependencies

To enable this parameter, set the Sensor array parameter to `Replicated subarray` and the Subarrays layout to `Custom`.

Version History

Introduced in R2018b