FMCW Waveform
Frequency modulated continuous wave (FMCW) generator.
Description
The FMCW Waveform unit generates a frequency modulated continuous waveform (FMCW) signal with a specified frequency increment time and frequency deviation . The output of the unit is an integer number of pulses or a sequence of samples.
Ports
Output
Port_1 - continuous emission signal with frequency modulation
`complex column vector
Output of the block defined as a complex vector-column containing samples of the signal. The number of samples in the signal depends on the following parameters:
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If the Output signal format parameter is set to
Samples, the block output is defined by the Number of samples in output parameter or the number of samples. -
If the Output signal format is set to
Sweeps, the block output is determined by the Number of sweeps in output or the number of frequency modulated pulses. -
If the Sweep direction parameters are set to
Triangle, the modulation period of the signal is twice the frequency increment time.
Parameters
Sample rate (Hz) - sampling rate
1e6 (by default) | positive scalar
The sampling frequency of the signal as a positive scalar. The unit of measurement is Hz.
The product of sampling frequency Sample rate (Hz) and frequency increment time Sweep time must be an integer.
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Sweep time (s) - period of the modelling signal with FM
1e-4 s (By default)
Time of frequency increment (Sweep time) is a scalar or vector-string of positive real numbers and can characterise both the increase of signal modulation frequency and its decrease. The units of measurement are seconds. The product of sampling rate (Sample rate) and time of frequency increment must be an integer.
To make the frequency increment time change in the output signal, set the Sweep time parameters as a vector string. The signal generator sequentially takes the corresponding vector value as the frequency increment time for its modulation period . When the last vector value is reached, the process continues from the beginning.
If the Sweep direction parameters are set to Up or Down, the modulation period of the signal is equal to the frequency increment time . If the Sweep direction parameters are set to Triangle, the modulation period of the signal is twice the frequency increment time , because each modulation period of the signal is made up of the rising frequency increment time and the falling frequency deviation time.
If parameters Sweep time and Sweep bandwidth are vector strings, then their dimensionality should coincide.
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*Sweep bandwidth (Hz)` - frequency deviation
1e5 Hz (By default)
Frequency deviation of signal with linear frequency modulation in the form of scalar or vector-string of positive real numbers. The units of measurement are Hz.
To make the frequency deviation change in the output signal, set the Sweep bandwidth parameters as a vector-string. The signal generator sequentially uses the corresponding vector value as the frequency deviation for its modulation period. When the last vector value is reached, the process continues from the beginning.
If the Sweep time and Sweep bandwidth parameters are vector strings, their dimensionality must be the same.
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Sweep direction - frequency deviation direction
Up (by default) | Down | Triangle
Frequency deviation direction:
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Up- frequency increase (Fig. 1a). -
Down- frequency decrease (Fig. 1b). -
Triangle- sequential increase and decrease of frequency (Fig. 2).
Sweep interval - location of the modulation interval
Positive (By default) | Symmetric
Frequency deviation interval specified as Positive or Symmetric:
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Positive- the signal frequency will vary between0andB, whereBis the value of the Sweep bandwidth parameters. -
Symmetric- the signal frequency will vary between-B/2andB/2.
Output signal format - output signal format
Sweeps (by default) | Samples.
Output signal format specified in the form:
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Sweeps- block output signal having the form of several frequency-modulated pulses, the number of which is defined by the parameters Number of sweeps in output. -
Samples- the block output signal having the form of a sequence of samples, the number of which is determined by the Number of samples in output parameter.
If the Sweep direction parameters are set to Triangle, the frequency increment time is half of the modulation period of the signal .
Number of samples in output - number of samples of the output signal
100 (By default) | `positive number
The number of samples of the output signal specified as a positive integer.
*Example: 1000
Dependencies
To use this parameter, set the Output signal format parameters to Samples.
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Number of sweeps in output - number of output pulses
1 (By default) | positive integer
The number of frequency modulated pulses of the output signal specified as a positive integer.
Dependencies
To use this parameter, set the Output signal format parameter to Sweeps.
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By default |
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