# blindrangemap

## Syntax

## Description

## Examples

### Create Blind Range Map for Three PRFs

Start with a radar transmitting $5\text{\hspace{0.17em}}\mu \mathrm{sec}$ long pulses. The radar covers the range from $0-100$ km. Create a blind range map when the pulse repetition frequencies are 5000, 10000, and 15000 kHz. Ranges from 18.5 km to 19.8 km and from 30 km to 32 km are obstructed due to clutter.

R = linspace(0,100e3,1000);

Choose the three PRFs at 5000, 10000, and 15000 kHz.

PRF = [5e3,10e3,15e3];

Compute the minimum range of the radar from the pulse duration.

```
tau = 5e-6;
rmin = time2range(tau,physconst('LightSpeed'));
```

Add two clutter obstruction regions and create the blind range map.

obs = [18.5e3 19.8e3;30e3 32e3]; blindrangemap(R,PRF,rmin,obs)

### Create Blind Range Map with Range Masks

A pulse radar transmits at two pulse repetition frequencies (PRF): 10.151 kHz and 14.163 kHz. Set the minimum detectable range of the radar to 1000 m. Sidelobe clutter extends from 34.5 km to 36.5 km when transmitting at the first PRF, and from 36.3 km to 39.8 km when transmitting at the second PRF. Display the blind range map for ranges between 0 and 100 km at 1 km increments.

R = linspace(0,100e3,1000);

Set the minimum detectable range to 1000 m.

Rmin = 1000;

Set the two PRF values.

PRF = [10151 14163];

Account for blind ranges due to sidelobe clutter using the range mask input argument. First, initialize the map to indicate that all ranges are visible.

rangeMask = false(numel(R),numel(PRF));

Then, mask the sidelobe clutter at PRF = 10.151 kHz.

rangeMask(R > 34500 & R < 36500,1) = true;

Mask the sidelobe clutter at PRF =14.163 kHz.

rangeMask(R > 36300 & R < 39800,2) = true;

Display the blind range map.

`blindrangemap(R,PRF,Rmin,'RangeMask',rangeMask)`

## Input Arguments

`R`

— Map range

length-*J* vector of positive values

Map range, specified as a length-*J* vector of positive values. The
function computes the blind range map at these ranges. Units are in meters.

**Example: **`[4000,4500,6000]`

**Data Types: **`double`

`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.

**Example: **`[10000,15000]`

**Data Types: **`double`

`Rmin`

— Minimum detection range

positive scalar | length-*N* vector of positive values

Minimum detection range, specified as a positive scalar or
length-*N* vector of positive values. Ranges between 0 and
`Rmin`

are blind to the radar.

If the radar transmits pulses of fixed duration,

`Rmin`

must be a scalar and the size of the blind zone is the same for all PRF values.If the radar transmits pulses with having a constant duty cycle,

`Rmin`

is a length-*N*vector and the size of the blind zone may be different for each PRF.

Blind zones also occur at integer multiples of the radar unambiguous
range *R*_{uamb} = *c/(2*PRF)*
where *c* is the signal propagation speed. Units are in meters.

**Example: **`40000`

**Data Types: **`double`

`obstr`

— Obstructions in range

*Q*-by-2 matrix

Obstructions in range, specified as a *Q*-by-2 matrix of positive
values. The *q*^{th}-row specifies a range
obstruction in the form `[rstartq,rstopq]`

where
`rstartq`

and `rstopq`

are the start and stop ranges
of the *q*^{th} obstruction such that
`rstopq`

≥ `rstartq`

. Targets located at the
obstructed ranges or ranges ambiguous to the obstructed ranges are not visible to the
radar. Such range obstructions are caused by, for example, clutter, multipath
interference, or jammer interference. Entries in `BRM`

that
correspond to obstructed ranges are set to a logical one (true). Otherwise, they are
zero (false). Units are in meters.

**Example: **`[30000;31000]`

**Data Types: **`double`

`rm`

— Range mask

*J*-by-*N* matrix of logical zeros. (default) | *J*-by-*N* logical matrix

Range mask, specified as a *J*-by-*N* logical
matrix. The rows of `rm`

correspond to ranges in
`R`

and the columns correspond to pulse repetition frequencies in
`PRF`

. `rm`

`(j,n)`

is a logical
zero (false) if the `j`

^{th} range cell is
visible to the radar at the `n`

^{th} frequency
in *PRF*. `rm`

`(j,n)`

is logical
one (true) if the `j`

^{th} cell is blind to the
radar at the `n`

^{th}
*PRF*. `rm`

can be used to specify ranges that are
blind due to sidelobe clutter.

**Data Types: **`double`

## Output Arguments

`BRM`

— Blind range map

*J*-by-*N* logical matrix

Blind range map, returned as a *J*-by-*N* logical
matrix. Each row of `BRM`

represents a range cell for the range equal
to the *j*^{th} entry in
`R`

. Each column of `BRM`

corresponds to the
*n*^{th} pulse repetition frequency in
`PRF`

. If the *j*^{th}
range cell is visible to the radar at the
*n*^{th}
`PRF`

, `BRM`

`(j,n)`

is a logical
zero (false), otherwise `BRM`

`(j,n)`

is a logical
one (true).

**Data Types: **`logical`

`U`

— Proportion of visible ranges

length-*N* vector

## Extended Capabilities

### C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

## Version History

**Introduced in R2023a**

## See Also

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