Continuous Wave

Model constant envelope source

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Libraries:
RF Blockset / Circuit Envelope / Sources

Description

The Continuous Wave block models a constant modulation on a carrier in the RF Blockset™ circuit envelope simulation environment. For an introduction to RF simulation, see the example, Simulate High Frequency Components.

The block implements the relation

$$v(t)=v_0{e}^{j{\omega }_{k}t}$$

or

$$i(t)=i_0{e}^{j{\omega }_{k}t}$$

at the carrier ω_k, depending on the source type.

Continuous Wave block mask icons are dynamic and show the current state of the applied noise parameter. For more information, see Continuous Wave Block Icons.

Examples

Carrier to Interference Performance of Weaver Receiver

A classic superheterodyne architecture filters images prior to frequency conversion. In contrast, image-reject receivers remove the images at the output without filtering but are sensitive to phase offsets.

• Open Script

Model LO Phase Noise

Model and visualize LO phase noise. A mixer transfers local oscillator (LO) phase noise directly to its output.

• Open Script

Parameters

Source type — Wave type

Ideal voltage (default) | Ideal current | Power

• Ideal Voltage — The block simulates a constant voltage envelope v₀ at the specified Carrier frequencies. The envelope has real and imaginary parts specified by the Constant in-phase value and Constant quadrature value parameters.

• Ideal Current — The block simulates a constant current envelope i₀ at the specified Carrier frequencies. The envelope has real and imaginary parts determined by the Constant in-phase value and Constant quadrature value parameters.

• Power — The block simulates the constant voltage envelope

  $$v_0=2\sqrt{{\text{P}}_0\text{Re}\left(Z_s\right)}{e}^{j\frac{\pi }{180}\varphi }$$

  where:

  • P₀ is the value of the Available power parameter

  • Z_s is the value of the Source impedance (ohms) parameter.

  • ϕ is the value of the Angle (degrees) parameter.

Constant in-phase value — In-phase modulations of carrier frequencies

0 V (default) | vector of real numbers | V | mV | kV

In-phase modulations for each of the Carrier frequencies, specified as a vector of real numbers. Specify the units from the corresponding drop-down list.

Dependencies

To enable this parameter, on the Source type tab, choose Ideal voltage or Ideal current.

Constant quadrature value — Quadrature modulations of carrier frequencies

0 V (default) | vector of real numbers | V | mV | kV

Quadrature modulations for each of the RF circuit carrier frequencies, specified as a vector of real numbers. Specify the units from the corresponding drop-down list.

Dependencies

To enable this parameter, on the Source type tab, choose Ideal voltage or Ideal current.

Source impedance(Ohm) — Input impedance of source

50 (default) | positive real number | complex number

Input impedance of source, specified as a positive real number or a complex number. The complex number must contain real and imaginary parts greater than or equal to 1e-18 ohms.

Dependencies

To enable this parameter, on the Source type tab, choose Power.

Available power — Available power of carrier frequencies

0 W (default) | vector of real numbers | W | mW | dBW | dBm

Available power at the specified Carrier frequencies, specified as a vector of real numbers. Specify the units from the drop-down list. The default value is 0 W.

Dependencies

To enable this parameter, on the Source type tab, choose Power. The default value is 0 W

Angle(degrees) — Phase angle of power waves

0 (default) | vector of real numbers

Phase angle of power waves at the specified Carrier frequencies, specified as a vector of real numbers. The default value is 0 degrees.

Dependencies

To enable this parameter, on the Source type tab, choose Power.

Carrier frequencies — Carrier frequencies

0 (default) | vector of real positive numbers | Hz | kHz | MHz | GHz

Carrier frequencies, specified as a vector of real positive numbers. The elements in the carrier frequencies are combinations of fundamental tones and corresponding harmonics in the Configuration block. The default value is 0 Hz.

Add phase noise — Add phase noise

off (default) | on

Select this parameter, to add phase noise to your system with continuous wave source.

Phase noise frequency offset (Hz) — Phase noise frequency offset

0 (default) | scalar | vector | matrix

Phase noise frequency offset, specified as a scalar or vector or matrix with each element units in hertz.

If you specify a matrix, each column should correspond to a non-DC carrier frequency of the CW source. The frequency offset values must be bounded by the envelope bandwidth of the simulation. For more information see, Configuration.

Dependencies

To enable this parameter, select Add phase noise.

Phase noise level (dBc/Hz) — Phase noise level

0 (default) | scalar | vector | matrix

Phase noise level, specified as a scalar or vector or matrix with element unit in decibel per hertz.

If you specify a matrix, each column should correspond to a non-DC carrier frequency of the CW source. The frequency offset values must be bounded by the envelope bandwidth of the simulation. For more information see, Configuration.

Dependencies

To enable this parameter, select Add phase noise.

Automatically estimate impulse response duration — Automatically estimate impulse response duration

on (default) | off

Select this parameter to automatically calculate impulse response for phase noise. Clear this parameter to manually specify the impulse response duration using Impulse response duration.

Dependencies

To enable this parameter, select Add phase noise.

Impulse response duration — Impulse response duration

1e-10s (default) | scalar

Impulse response duration used to simulate phase noise, specified as a scalar in seconds. You cannot specify impulse response if the amplifier is nonlinear.

Note

The phase noise profile resolution in frequency is limited by the duration of the impulse response used to simulate it. Increase this duration to improve the accuracy of the phase noise profile. A warning message appears if the phase noise frequency offset resolution is too high for a given impulse response duration, specifying the minimum duration suitable for the required resolution

Dependencies

To set this parameter, first clear Automatically estimate impulse response duration.

Plot phase noise characteristics — Phase noise magnitude response

button

The block plots the phase noise characteristics based on the parameters specified in the Impairments tab and either the Envelope bandwidth parameter in the Configuration block when available or the value specified in the Phase noise frequency offset (Hz) parameter.

Dependencies

To enable this parameter, select Add phase noise.

Ground and hide negative terminals — Ground RF circuit terminals

on (default) | off

Select this option to internally ground and hide the negative terminals. To expose the negative terminals, clear the option. By exposing these terminals, you can connect them to other parts of your model.

Algorithms

Continuous Wave Block Icons

This table shows you how the icons on this block vary based on the state of the Simulate noise and Source type parameters on the block.

Source type	Simulate noise: on	Simulate noise: off
Ideal voltage
Ideal current
Power

Version History

Introduced in R2010b

R2022b: Estimate impulse response duration using phase noise offset frequencies

The Continuous Wave block estimates the impulse response duration using the Phase noise frequency offset (Hz) parameter and visualizes the phase noise characteristics when you click the Plot phase noise characteristics button.

R2021b: Continuous Wave block icon updated

Starting in R2021b, the Continuous Wave block icon is now updated. The block icons are now dynamic and show the current state of the noise parameter.

When you open a model created before R2021b containing a Continuous Wave block, the software replaces the block icon with the R2021b version.