Engee documentation

Range Response

Range Response.

range response

Description

The Range Response block performs fast time (range) data filtering using either a matched filter or an FFT based algorithm. The output signal is typically used as the input signal to the detector. Matched filtering improves the signal-to-noise ratio (SNR) of pulsed signals. For continuous FM signals, FFT processing can extract the beat frequency of FMCW signals. The beat frequency is directly related to the range.

Ports

Input

X - cube of input data
complex vector-column K on 1 | complex matrix K on L | complex array K on N on L

A cube of input data, given as a complex vector-column K on 1, a complex-valued matrix K on L, or a complex-valued array K on N on L.

  • K is the number of range or time samples.

  • N is the number of independent channels, such as sensors or directions.

  • L - number of pulses or sweeps in the input signal.

Each K-element vector-column is processed independently.

For FMCW signal with triangular sweep, the sweeps alternate with positive and negative slope. However, the Range Response block is designed to process successive sweeps with the same slope. To apply Range Response to a triangular sweep system, use one of the following approaches:

  • Set the Sweep slope parameters to a positive value, with X corresponding to the upward sweep only. After obtaining the Doppler velocity or motion velocity values, divide them by 2.

  • Set the Sweep slope parameters to a negative value, with X corresponding to down sweep only. After obtaining the Doppler velocity or speed values, divide them by 2.

The number of samples for the first dimension of the input matrix can be varied to simulate a change in signal length. A change in dimension can occur, for example, in the case of a pulse waveform with a variable pulse repetition rate.

Data types: Float16, Float32, Float64, Int8, Int16, Int32, Int64, UInt8, UInt16, UInt32, UInt64.

Support for complex numbers: Yes.

Coeff - matched filter coefficients
`complex column vector'.

The coefficients of the matched filter, given as a complex vector-column. The length of the vector must be less than or equal to the number of rows in the input data, K.

Dependencies

To use this port, set Range processing method to Matched filter.

Data types: Float16, Float32, Float64, Int8, Int16, Int32, Int64, UInt8, UInt16, UInt32, UInt64.

Support for complex numbers: Yes.

XRef - reference signal
`Complex vector-column K at 1

The reference signal used to decode the input signal is specified as a complex-valued column vector (K-by-1). The number of rows must be equal to the length of the first dimension X.

Dependencies

To enable this port, set Range processing method to FFT and select the Dechirp input signal parameters.

Data types: Float16, Float32, Float64, Int8, Int16, Int32, Int64, UInt8, UInt16, UInt32, UInt64.

Support for complex numbers: Yes.

Output

Range - range values
`actual vector-column M by 1'

Range values on the first measurement of the Resp output data port data, specified as a real-valued column vector (M-by-1). This value defines the range values on the first data measurement of the Resp output data port. The units of measurement are metres.

Data types: Float16, Float32, Float64, Int8, Int16, Int32, Int64, UInt8, UInt16, UInt32, UInt64.

Parameters

Range processing method - range processing method
Matched filter (by default) | FFT

Range processing method specified as Matched filter or FFT.

  • Matched filter - The block applies a matched filter to the incoming signal. This approach is typically used for pulsed signals, where the matched filter is the temporal inverse of the transmitted signal.

  • FFT - the block applies an FFT to the input signal. This approach is typically used for FMCW and linear FM pulse signals.

Data types: Float16, Float32, Float64, Int8, Int16, Int32, Int64, UInt8, UInt16, UInt32, UInt64.

Propagation speed (m/s) - speed of signal propagation
3e8 (by default) | Positive scalar

Signal propagation speed, specified as a real positive scalar. By default, the value for the speed of light is: 3e8.

Data types: Float16, Float32, Float64, Int8, Int16, Int32, Int64, UInt8, UInt16, UInt32, UInt64.

Inherit sample rate - inherit sample rate
On (By default) | Off

Select the checkbox to inherit sample rate from upstream blocks. Otherwise, set the sample rate using the Sample rate (Hz) parameters.

Sample rate - sampling rate of the signal, Hz
1e6 (by default) | positive scalar.

Set the sampling rate of the signal as a positive scalar. The unit of measurement is Hz.

Dependencies

To use this parameters, clear the Inherit sample rate checkbox.

Data types: Float16, Float32, Float64, Int8, Int16, Int32, Int64, UInt8, UInt16, UInt32, UInt64.

FM sweep slope - FM sweep slope, Hz/c
1e9 (by default) | scalar

Set the slope of the FM linear sweep as a scalar. This parameter should correspond to the actual sweep of the input data in port X.

Dependencies

To use this parameter, set the Range processing method parameters to FFT.

Data types: Float16, Float32, Float64, Int8, Int16, Int32, Int64, UInt8, UInt16, UInt32, UInt64.

Dechirp input signal - enable input signal decryption
on (by default) | `off

Select this checkbox to make the unit perform the input signal decryption operation. Clear this check box to indicate that the input signal has already been decoded and no decoding operation is required.

Dependencies

To use this parameter, set the Range processing method parameter to FFT.

Source of FFT length in range processing - source of FFT length
Auto (By default) | Property.

The source of FFT length used for processing decrypted signals in range is set as Auto or Property.

  • Auto - The FFT length is equal to the length of the fast time measurement of the input data cube.

  • Property - Specify the FFT length using the FFT length in range processing parameters.

Dependencies

To use this parameter, set the Range processing method parameters to FFT.

FFT length in range processing - length of FFT of range processing
Auto (By default) | Property.

FFT length for range processing, set as a positive integer.

Dependencies

To use this parameter, set the Range processing method parameter to FFT and the Source of FFT length in range processing parameter to Property.

Data types: Float16, Float32, Float64, Int8, Int16, Int32, Int64, UInt8, UInt16, UInt32, UInt64.

Range processing window - FFT length range processing
None | Hamming | Chebyshev | Hann | Kaiser | Taylor

Specify the window used to process the range using one of the following values: None, Hamming, Chebyshev, Hann, Kaiser, Taylor.

If you set this parameter to Taylor, the generated Taylor window will have four almost constant side petals adjacent to the main petal.

Dependencies

To use this parameter, set the Range processing method parameter to FFT.

Data types: Float16, Float32, Float64, Int8, Int16, Int32, Int64, UInt8, UInt16, UInt32, UInt64.

Range sidelobe attenuation level - sidelobe attenuation level
30 (By default) | scalar

Sidelobe attenuation level as a positive scalar.

This attenuation applies only to Chebyshev, Kaiser or Taylor windows. The unit of measurement is dB.

Dependencies

To use this parameter, set the Range processing method parameter to FFT and the Range processing window parameter to Chebyshev, Kaiser or Taylor.

Set reference range at centre - set reference range at grid centre
On (by default) | Off

Sets the reference range at grid centre, set as on or off. Checking this box sets the reference range at the centre of the grid. Otherwise, the reference range is set to the beginning of the grid.

Dependencies

To use this property, set the Range processing method parameters to FFT.

Data types: Float16, Float32, Float64, Int8, Int16, Int32, Int64, UInt8, UInt16, UInt32, UInt64.

Reference range - grid reference range, m
0.0 (by default) | non-negative scalar

Reference range of the range grid, specified as a non-negative scalar.

  • If the Range processing method parameters are set to Matched filter, the reference range is set to the beginning of the range grid.

  • If the Range processing method parameters are set to FFT, the reference range depends on the Set reference range at centre checkbox.

    • If Set reference range at centre is checked, the reference range will be set at the centre of the range grid.

    • If the Set reference range at centre checkbox is unchecked, the reference range will be set at the beginning of the range grid. The units of measurement are metres.

*Example: 1000.0

Data types: Float16, Float32, Float64, Int8, Int16, Int32, Int64, UInt8, UInt16, UInt32, UInt64