This page describes radars which use a simultaneous multiplexing technique.
In Ansys AVxcelerate Sensors Simulator, you can simulate radars that use a multiplexing technique.
Multiplexing is a technique in which multiple signals are combined over a shared medium.
AVxcelerate Sensor Labs allows you to define radars that utilize one of
two multiplexing types:
Note:This feature is delivered in the
current release as a Beta Feature.
Overview of the Simultaneous Mode
A radar with a simultaneous mode contains multiple emitters (Tx antennas) and one or multiple
receivers (Rx antennas). In this configuration, all the Tx antennas of a single mode emit
waveforms simultaneously, and the signals are added together as though there were only one Tx
antenna, similar to a radar with a simple mode.
With this
configuration, when you are working with System Pulse Doppler or FMCW radars, the signal
(Number of Chirps/Pulses per CPI) is the same for all Tx antennas in the mode since the Tx antennas have simultaneous
emission.
As a result, a radar with two Tx antennas and 400 chirps per CPI will assign 400 chirps to
each one of the Tx antennas.
Figure 1. Simultaneous Signal
Beamforming
In Ansys AVxcelerate Sensors Simulator, the beamforming capability is available in radars with a
simultaneous mode. Beamforming is a signal processing technique that focuses the signals of
multiple Tx antennas in order to direct the waveform towards a specific location. In radars with
beamforming capabilities, the signals from the Tx antennas in an antenna array, each with
different amplitudes and phases, are combined so that some waveforms are added together
(constructive interference) and others are canceled out (destructive interference). When the
signals are combined constructively, the power which is radiated in the intended direction is
amplified as it forms the main beam, a radiation pattern which transmits the signal in the
desired direction. Inversely, power which is radiated in other directions experience destructive
interference forming nulls and side lobes which limit the energy sent in those directions.Beamforming enhances the radar's detection of objects by modifying the power of the signal
emitted by the antennas and focusing the main beam of the radar to specific areas. To create a
radar model with beamforming capabilities, in the mode configuration of a radar in AVxcelerate Sensor Labs or its API, you can select the
SimultaneousMultiplexing Type and upload a *.txt file to add the Transmitter Weighting Sequence. The Transmitter
Weighting Sequence file is composed of complex weightings used to determine the
amplitude and phase of each Tx antenna.
Arbitrary (Advanced) Waveforms [Beta
Feature]
In Ansys AVxcelerate Sensors Simulator, two additional types of waveforms are supported in radars with
a simultaneous mode:
Non-arbitrary waveforms, that is, Performance FMCW, System
FMCW, Performance Pulse Doppler and System Pulse
Doppler waveforms, are uniform. Therefore, each pulse or chirp in the CPI and the
interval between them is identical. With Arbitrary Pulse Doppler and
Arbitrary FMCW waveforms, pulse or chirp properties and the time interval
between pulses or chirps can vary. The variation in the chirp properties allows the response
from the radar to be better isolated, resulting in less interference for digital signal
processing. Below is the list of properties for which there is a variation and which can be
provided in the Pulse Sequence and Chirp Sequence
files respectively. For:
Arbitrary Pulse Doppler
Center Frequency
Bandwidth
Number of Frequency Samples
Time Interval to Next Pulse.
Arbitrary FMCW
Center Frequency
Sampling Rate
Number of Frequency Samples
Time Interval to Next Chirp.
The Output for arbitrary waveforms is always Raw
Response. If Shared Memory Access is not disabled in the
Radar Simulation Parameters, when a Tx Waveform report is produced,
a Response to Tx Waveform Map can also be found in the output to shared memory. The Response to
Tx Waveform map allows you to interpret the data by associating each line of the response data
from arbitrary waveforms (Arbitrary FMCW ADC output and the Pulse Frequency Response) to a line
in the Tx Waveform report.
Tip: To retrieve all data, you may need to change the data
retention strategy by increasing the maxstored data for shared
memory.
To create a radar with an arbitrary waveform:
In the Mode Configuration of a radar in AVxcelerate Sensor Labs or its API, set the Multiplexing
Type parameter to Simultaneous.
Set the Waveform parameter to:
Arbitrary Pulse Doppler
Arbitrary FMCW.
If you want to provide the Transmitter Weighting Sequence, upload a
compliant *txt file in the Transmitter Weighting Sequence field
according to the Waveform selected.
If you selected Arbitrary Pulse Doppler upload a compliant *.txt file in the Pulse Sequence field.
If you selected Arbitrary FMCW upload a compliant *.txt file in the Chirp Sequence field.
The Transmitter Weighting Sequence file is a *.txt file which contains
complex weightings consisting of a pair of numbers representing real and imaginary parts. These
weightings can be used to determine the amplitude and phase of each Tx antenna.
To define the complex weightings for a radar mode, you can upload a file in the
Transmitter Weighting Sequence field of the radar mode configuration in
AVxcelerate Sensor Labs or its API.
Note:This parameter is optional. If
you do not upload a file, the complex weightings will be assigned a default value of 1.
Consequently the Tx antennas will emit at a maximum amplitude and there will be no phase
offset.
The weightings can be expressed in one of two ways:
per Tx antenna.
per chirp or pulse for each Tx antenna.
You can find sample Transmitter Weighting Sequence
files in [AVxcelerate Sensors Standalone Library Installation
Directory]/AVX_Library_v251/Sensors/models/samples.
Transmitter Weighting Sequence per Tx Antenna
To provide the Transmitter Weighting
Sequence file per Tx antenna, you must create a *.txt file with the following structure:
File description
Comments
Weighting by Transmitter
Number of Tx antennas
Tx0R Tx0i Tx1R Tx1i Tx2R Tx2i
where Tx0R and Tx0i are complex numbers representing the real and imaginary parts for Tx0,
etc.
there is one pair of values (real and imaginary) per Tx antenna.
To ensure consistency, the number of pairs of values
in the line must be same as the number of Tx antennas specified within the file and in the
mode configuration of the radar sensor.
Transmitter Weighting Sequence per Pulse or Chirp
To provide the Transmitter Weighting Sequence file per pulse or per chirp for each
transmitter, you must create a *.txt file whose structure must comply with the requirements
according to the waveform it uses. For:
System Pulse Doppler
File description
Comments
Weighting by pulses
Number of Tx antennas
Number of pulses
Note: The number of pulses =
Number of Pulses in CPI
Tx0R Tx0i Tx1R Tx1i Tx2R
Tx2ion pulse 1
where Tx0R and Tx0i are complex numbers representing the real and imaginary parts per
pulse for Tx0, etc.
there is one pair of values (real and imaginary) per pulse for each Tx antenna
To ensure consistency, the number of pairs of values
in the line must be same as the number of Tx antennas specified within the file and in the
mode configuration of the radar sensor.
Tx0R Tx0i Tx1R Tx1i Tx2R
Tx2ion pulse 2
...
...
Tx0R Tx0i Tx1R Tx1i Tx2R
Tx2ion pulse [number of pulses]
Note:The number
of lines from line 6 to the end of the file must be the same as the number of pulses.
System FMCW
File description
Comments
Weighting by Chirps
Number of Tx antennas
Number of Chirps
Note: Number of chirps =
Number of chirps in CPI
Tx0R Tx0i Tx1R Tx1i Tx2R
Tx2ion chirp 1
where Tx0R and Tx0i are complex numbers representing the real and imaginary parts per
chirp for Tx0, etc.
there is one pair of values (real and imaginary) per chirp for each Tx antenna
To ensure consistency, the number of pairs of values
in the line must be same as the number of Tx antennas specified within the file and in the
mode configuration of the radar sensor.
Tx0R Tx0i Tx1R Tx1i Tx2R
Tx2ion chirp 2
...
...
Tx0R Tx0i Tx1R Tx1i Tx2R
Tx2i on chirp [number of chirps]
Note:The number
of lines from line 6 to the end of the file must be the same as the number of chirps.
Performance Pulse Doppler or Performance FMCW
File description
Comments
Weighting by pulses or
chirps
Number of Tx antennas
Number of pulses or
chirps
Note: Number of pulses or chirps = round up (Target Velocity
Period / Target Velocity Resolution)
Tx0R Tx0i Tx1R Tx1i Tx2R
Tx2ion pulse or chirp 1
where Tx0R and Tx0i are complex numbers representing the real and imaginary parts per
pulse or chirp for Tx0, etc.
there is one pair of values (real and imaginary) per pulse or chirp for each Tx
antenna
To ensure consistency, the number of pairs of values
in the line must be same as the number of Tx antennas specified within the file and in the
mode configuration of the radar sensor.
Tx0R Tx0i Tx1R Tx1i Tx2R
Tx2ion pulse or chirp 2
...
...
Tx0R Tx0i Tx1R Tx1i Tx2R
Tx2ion pulse or chirp [number of pulses or chirps]
Note:The number
of lines from line 6 to the end of the file must be the same as the number of pulses or
chirps.
Arbitrary Pulse Doppler[Beta
Feature]
File description
Comments
Weighting by pulses
Number of Tx antennas
Number of pulses
Note: The number of pulses must be the same as the number of pulses
defined in the Pulse Sequence file
Tx0R Tx0i Tx1R Tx1i Tx2R
Tx2ion pulse 1
where Tx0R and Tx0i are complex numbers representing the real and imaginary parts per
pulse for Tx0, etc.
there is one pair of values (real and imaginary) per pulse for each Tx antenna
To ensure consistency, the number of pairs of values
in the line must be same as the number of Tx antennas specified within the file and in the
mode configuration of the radar sensor.
Tx0R Tx0i Tx1R Tx1i Tx2R
Tx2i on pulse 2
...
...
Tx0R Tx0i Tx1R Tx1i Tx2R
Tx2ion pulse [number of pulses]
Note:The number
of lines from line 6 to the end of the file must be the same as the number of pulses.
Arbitrary FMCW[Beta
Feature]
File description
Comments
Weighting by Chirps
Number of Tx antennas
Number of Chirps
Note: The number of chirps must be the same as the number of chirps in the
Chirp Sequence file.
Tx0R Tx0i Tx1R Tx1i Tx2R
Tx2ion chirp 1
where Tx0R and Tx0i are complex numbers representing the real and imaginary parts per
chirp for Tx0, etc.
there is one pair of values (real and imaginary) per chirp for each Tx antenna
To ensure consistency, the number of pairs of values
in the line must be same as the number of Tx antennas specified within the file and in the
mode configuration of the radar sensor.
Tx0R Tx0i Tx1R Tx1i Tx2R
Tx2ion chirp 2
...
...
Tx0R Tx0i Tx1R Tx1i Tx2R
Tx2ion chirp [number of chirps]
Note:The number
of lines from line 6 to the end of the file must be the same as the number of chirps.
Pulse Sequence File [Beta
Feature]
With the Arbitrary Pulse DopplerWaveform, certain
pulse properties of the waveform vary with each pulse. Likewise, the interval between each pulse
differs. To provide these variations, you must upload a *.txt file to the Pulse
Sequence field in the Mode configuration of your radar.
The Pulse Sequence file provides the variation in the following pulse
properties of the Arbitrary Pulse DopplerWaveform:
Center Frequency
Bandwidth
Number of Frequency Samples
Time Interval to Next Pulse.
You can find a sample Pulse Sequence file in [AVxcelerate Sensors Standalone Library Installation Directory]/AVX_Library_v251/Sensors/models/samples.
To create a compliant Pulse Sequence file, you must create a *.txt file
with the following format:
File description
Comments
Number of pulses
prop1 prop2 prop3 prop4on pulse 1
where prop1 is the Center Frequency in GHz
prop2 is the Bandwidth in MHz
prop3 is the Number of Frequency Samples
prop4 is the Time Interval to Next Pulse in μs.
prop1 prop2 prop3 prop4on pulse 2
...
...
prop1 prop2 prop3 prop4on pulse [number of pulses]
Note:The number of lines from line 4 to the end of
the file must be the same as the number of pulses.
Chirp Sequence File [Beta
Feature]
With the Arbitrary FMCWWaveform, certain chirp
properties of the waveform vary with each chirp. Likewise, the interval between each chirp
differs. To provide these variations, you must upload a *.txt file to the Chirp
Sequence field in the Mode configuration of your radar.
The Chirp Sequence file provides the variation in the following chirp
properties of the Arbitrary FMCWWaveform:
Center Frequency
Sampling Rate
Number of Frequency Samples
Time Interval to Next Chirp.
You can find a sample Chirp Sequence file in [AVxcelerate Sensors Standalone Library Installation Directory]/AVX_Library_v251/Sensors/models/samples.
To create a compliant Chirp Sequence file, you must create a *.txt file
with the following format:
File description
Comments
Ramp rate in MHz/μs
Note: This property is fixed
across all chirps.
Radar Channel
In-phase
In-phase and Quadrature
Note: This property is fixed
across all chirps.
Number of chirps
prop1 prop2 prop3 prop4on chirp 1
where prop1 is the Center Frequency in GHz
prop2 is the Sampling Rate in MHz
prop3 is the Number of Samples
prop4 is the Time Interval to Next Chirp in μs.
prop1 prop2 prop3 prop4on chirp 2
...
...
prop1 prop2 prop3 prop4on chirp [number of chirps]
Note:The number of lines from line 6 to the end of
the file must be the same as the number of chirps.
