Backscatter Bicyclist
A model of the backscatter pattern of signals from a cyclist.
Description
The Backscatter Bicyclist block simulates the monostatic reflection of unpolarised electromagnetic signals from a cyclist. A bicyclist consists of a bicycle and its rider. The block models the motion of the cyclist and computes the sum of all reflected signals from multiple discrete scatterers on the cyclist. The model ignores the internal hidden parts of the cyclist. The reflected signals are calculated using a multiple scatterer model developed from a 77 GHz radar system.
The scatterers are located on the five main components of the cyclist:
-
The bicycle frame and the cyclist
-
Bicycle pedals
-
Upper and lower parts of the cyclist’s legs
-
Front wheel
-
Rear wheel
With the exception of the wheels, there are 114 diffusers on the cyclist. Wheels contain diffusers on the rim and spokes. The number of scatters on the wheels depends on the number of spokes on the wheel, which can be set using the NumWheelSpokes property.
Ports
Input
#
X
—
random radar signals
`complex matrix M over N
Details
The radar input signals at each cyclist scatterer, given as a complex matrix by . - Is the number of samples in the signal. - is the number of point scatterers on the cyclist, which is partly determined by the number of spokes in each wheel, argument Nws. For a column representing the incident signal at each scatterer, see Cyclist scattering indices.
| Data types |
|
| Complex numbers support |
Yes |
#
Ang
—
input signal direction
real matrix 2 by N
Details
The incident signal directions to the cyclist segments given as a real matrix by . Each column Ang specifies the direction of the incident signal as a pair [AzimuthAngle;ElevationAngle].
See Cyclist Scattering Indices for the column representing the incident signal at each cyclist segment.
| Data types |
|
| Complex numbers support |
No |
#
AngH
—
cyclist’s direction of travel
scalar
Details
The direction of motion of a cyclist, given as a scalar. The direction is measured in the plane from the axis towards the axis .
| Data types |
|
| Complex numbers support |
No |
#
Speed
—
cycling speed
`non-negative scalar
Details
The speed of a cyclist given as a non-negative scalar. The motion model limits the speed to 60 m/s.
| Data types |
|
| Complex numbers support |
No |
#
Coast
—
coasting
false (by default) | true
Details
Cyclist inertia state, set as false or true.
-
If set to `true', the cyclist does not pedal, but the wheels continue to rotate (free running).
-
If set to `false', the cyclist pedals and the Gear transmission ratio parameter defines the ratio of wheel to pedal revolutions.
| Data types |
|
| Complex numbers support |
No |
Output
#
Y
—
combined reflected radar signals
`complex vector M at 1'
Details
Combined reflected radar signals returned as a complex vector by columns. equals the same number of samples as in the input signal X.
| Data types |
|
| Complex numbers support |
Yes |
#
Pos
—
cyclist segment positions
real matrix 3 by N
Details
The positions of the cyclist segments, returned as a real matrix by . Each column represents the Cartesian coordinates, [x;y;z], of one of the cyclist’s segments.
See Cyclist Scattering Indices for the column representing the incident signal on each cyclist segment.
| Data types |
|
| Complex numbers support |
No |
#
Vel
—
velocity of cyclist segments
real matrix 3 by N
Details
The velocity of the cyclist’s segments, returned as a real matrix by . Each column represents the Cartesian coordinates of the velocity, [vx;vy;vz], of one of the cyclist’s segments.
See Cyclist Scattering Indices for the column representing the incident signal on each cyclist segment.
| Data types |
|
| Complex numbers support |
No |
#
Ax
—
orientation of the cyclist’s segments
real matrix 3 by 3
Details
Orientation axes of cyclist segments returned as a real matrix by .
| Data types |
|
| Complex numbers support |
No |
Parameters
Main
#
Number of wheel spokes —
spoke count
Real number
Details
The number of spokes on a bicycle wheel, given as a positive integer from 3 up to and including 50.
| Default value |
|
| Program usage name |
|
| Tunable |
No |
| Evaluatable |
Yes |
#
Gear transmission ratio —
gear ratio
Real number
Details
The ratio of wheel revolutions to pedal revolutions, given as a positive scalar. The gear ratio should be in the range from 0.5 to 6.
| Default value |
|
| Program usage name |
|
| Tunable |
No |
| Evaluatable |
Yes |
#
Signal carrier frequency (Hz) —
carrier frequency
Real number
Details
The carrier frequency of narrowband incident signals, given as a positive scalar.
| Default value |
|
| Program usage name |
|
| Tunable |
No |
| Evaluatable |
Yes |
#
Initial position (m) —
cyclist’s starting position
Vector of real numbers
Details
The initial position of the cyclist given as a real vector on in the form [x;y;z].
| Default value |
|
| Program usage name |
|
| Tunable |
No |
| Evaluatable |
Yes |
#
Initial heading direction (deg) —
cyclist’s direction of travel
Real number
Details
The initial direction of the cyclist’s movement, given as a scalar. The direction is measured in the plane from the axis towards the axis .
| Default value |
|
| Program usage name |
|
| Tunable |
No |
| Evaluatable |
Yes |
#
Initial bicyclist speed (m/s) —
initial speed of the cyclist
Real number
Details
The initial velocity of the cyclist, given as a non-negative scalar. The motion model limits the speed to a maximum of `60 m/s (`216 km/h).
| Default value |
|
| Program usage name |
|
| Tunable |
No |
| Evaluatable |
Yes |
#
Propagation speed (m/s) —
signal propagation speed
Real number
Details
The propagation velocity of a signal given as a real positive scalar.
| Default value |
|
| Program usage name |
|
| Tunable |
No |
| Evaluatable |
Yes |
#
Source of radar cross section pattern —
radar cross-section diagram source
Auto | Property
Details
Radar Cross Section (RCS) diagram source, specified as Auto or Property.
-
If
Autois specified, the pattern is a1by361matrix containing values derived from radar measurements at 77 GHz.
| Values |
|
| Default value |
|
| Program usage name |
|
| Tunable |
No |
| Evaluatable |
No |
#
Azimuth angles (deg) —
azimuthal angles of the antenna radiation pattern
Vector of real numbers
Details
Azimuth angles used to determine the angular coordinates of each column of the matrix defined by the Radar cross section pattern (square metres) parameters. Define the azimuth angles as a vector of length P. P must be greater than two.
Dependencies
To use this parameter, set the Source of radar cross section pattern parameter to Property.
| Default value |
|
| Program usage name |
|
| Tunable |
No |
| Evaluatable |
Yes |
#
Elevation angles (deg) —
antenna radiation elevation angles
Scalar / vector of real numbers
Details
Elevation angles used to determine the angular coordinates of each row of the matrix defined by the Radar cross section pattern (square metres) parameters. Define the elevation angles as a vector of length Q. Q must be greater than two.
Dependencies
To use this parameter, set the Source of radar cross section pattern parameter to Property.
| Default value |
|
| Program usage name |
|
| Tunable |
No |
| Evaluatable |
Yes |
#
Radar cross section pattern (square meters) —
Radar cross-section diagram
Vector / matrix of real numbers
Details
A radar cross section (RCS) diagram as a function of elevation angle and azimuth, given as a real matrix at or a real vector at . - is the length of the vector defined by the ElevationAngles property. - is the length of the vector defined by the AzimuthAngles property.
You can also specify a template as a real vector of azimuth angles to for a single elevation.
By default, this property is a matrix to , containing values derived from 77 GHz radar measurements contained in the backscatterBicyclist.defaultRCSPattern file.
Dependencies
To use this parameter, set the Source of radar cross section pattern parameter to Property.
| Default value |
|
| Program usage name |
|
| Tunable |
No |
| Evaluatable |
Yes |
Additional Info
*Cyclist dispersion indices.
Cyclist scatter indices identify which columns of the scatterer position and velocity matrices contain data on the position and velocity of a particular scatterer. For example, column 92 of the `bpos' matrix defines the three-dimensional position of one of the scatterers on the pedal.
The wheel scatterers are equally distributed among the wheels. The total number of wheel scatterers, , can be determined by subtracting 113 from the result of the getNumScatterers function. The number of scatterers per wheel is .
Cyclist segment |
Cyclist dispersion index |
Frame and cyclist |
|
Pedals |
|
Cyclist’s legs |
|
Front wheel |
|
Rear wheel |
|