Engee documentation

EngeePhased.MFSKWaveform

Continuous emission generator with multi-frequency frequency modulation (MFSK).

Library

EngeePhased
Block

MFSK Waveform

Description

A continuous Multi-Frequency Frequency Modulated (MFSK) signal is used in automotive radars to improve simultaneous pulse and Doppler distance detection to multiple targets. The EngeePhased.MFSKWaveform system object generates a continuous MFSK signal. The MFSK signal consists of two alternating sequences of increasing frequencies, as described in Sect. Algorithms.

To obtain sample signals:

  • Define and configure the MFSK signal. See section Constructor.

  • Call step to generate MFSK signals according to the EngeePhased.MFSKWaveform properties. The behaviour of step is defined for each object in the toolbar. The output method of step is defined in the OutputFormat property, which does not affect the signal properties.

Constructor

  • sMFSK = EngeePhased.MFSKWaveform creates an MFSK signal system object, sMFSK.

  • The sMFSK = EngeePhased.MFSKWaveform(Name,Value) creates an MFSK signal system object, sMFSK, with additional properties specified by one or more arguments representing a name and value pair (Name,Value).

Properties

SampleRate - output sampling rate
1e6 (by default) | positive scalar

Details

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

Data types: Float64

SweepBandwidth - frequency deviation
1e5 (by default) | positive scalar

Details

Frequency deviation of a multi-position frequency modulated signal, specified as a positive scalar. The unit of measurement is Hz.

Signal frequency deviation is the difference between the highest and lowest frequencies of any of the sequences.

Data types: Float64

StepsPerSweep - total number of frequency deviation steps
64 (by default) | ` an odd positive number `

Details

The total number of frequency deviation steps specified as an even positive integer.

Data types: Float64

FrequencyOffset — frequency offset
1000 (By default) | real scalar

Details

Frequency offset specified as a real scalar. The frequency offset defines the frequency shift between two sequences.

Data types: Float64

OutputFormat - output format
Steps (by default) | Samples | Sweeps

Details

The output format accepts values:

  • Steps - the output signal is specified by the number of steps NumSteps.

  • Samples - the output signal is specified by the number of samples NumSamples.

  • Sweeps - the output signal of the block is specified by the number of steps by frequency deviation NumSweeps.

Values OutputFormat do not affect the signal properties.

NumSamples - number of samples in the signal
1 (by default) | positive integer

Details

The number of samples in the output sampling signal, specified as a positive integer.

Data types: Float64

NumSteps — number of steps in the signal
1 (by default) | positive integer

Details

The number of output steps specified as a positive integer.

Data types: Float64

NumSweeps - number of frequency deviation steps in the signal
1 (by default) | positive integer

Details

The number of output frequency deviation steps specified as a positive integer.

Data types: Float64

Methods

plot

Construct a continuous MFSK signal
reset

Reset the internal states of the MFSK signal object
step

Start the algorithm of MFSK signal object operation

Common to all system objects

release

Allow changing the value of a system object property

Algorithms

The MFSK signal consists of two alternating step-frequency sequences as shown in the time-frequency diagram.

so mfsk waveform 1

Each sequence is a set of continuous waveforms (CW) increasing in frequency. The offset between two sequences is constant and can be positive or negative. A complete signal consists of an even number of steps of equal duration . Then each sequence consists of stem[N//2] steps. The frequency deviation of the signal is the difference between the highest and lowest frequencies of any of the sequences. The value of is always positive, indicating an increase in frequency. The frequency deviation between consecutive steps of each sequence is defined as follows

.

The lowest frequency of the first sequence is always 0 Hz and corresponds to the carrier frequency of the bandpass signal. The lowest frequency of the second sequence can be positive or negative and is equal to . Negative frequencies correspond to frequencies of the bandpass signal that are lower than the carrier frequency. The duration of the signal is set by the value . The properties of the system object corresponding to the parameters of the signal are given in the table.

Signal parameters Property

SweepBandwidth

SweepBandwidth

SweepBandwidth

FrequencyOffset

References

  1. Meinecke, Marc-Michale, and Hermann Rohling, "Combination of LFMCW and FSK Modulation Principles for Automotive Radar Systems." German Radar Symposium GRS2000. 2000.

  2. Rohling, Hermann, and Marc-Michale Meinecke. "Waveform Design Principles for Automotive Radar Systems." CIE International Conference on Radar. 2001.