Scicos Block
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Nonlinear tunning characteristic of Voltage Controlled Oscillator block

Contents

• Nonlinear tunning characteristic of Voltage Controlled Oscillator block
  • Palette
  • Description
  • Basic blocks equivalent model
  • Dialog box
  • Default properties
  • Interfacing function
  • Computational function
  • See also
  • Authors
  • Bibliography

Palette

• NonLinear - NonLinear palette

Description

This block computes an hyperbolic tangent function. The output of this block is given by the following expression :

$$\begin{eqnarray} y=F\left(u\right)=\alpha \tanh\left(\beta u\right) \end{eqnarray}$$

with

• $\alpha$ : a gain (expressed in [rad/s]),
• $\beta$ : a coefficient (no unit).

Remember that $\tanh()$ is the hyperbolic tangent function defined by :

$$\begin{eqnarray} \tanh\left(x\right)=\frac{\exp(x)-\exp(-x)}{\exp(x)+\exp(-x)} \end{eqnarray}$$

In fact the output of this block provides a frequency deviation depending of the input voltage. The Fig.1 shows an example of this static function.

Figure 1: Static Voltage/Pulsation characteristic (alpha=6.91e9 rad/s, beta=0.15).

Basic blocks equivalent model

Dialog box

• Gain
  The alpha gain of the nonlinear characteristic.
  Properties : Type 'vec' of size -1.

• Coefficient
  The beta coefficient of the nonlinear characteristic.
  Properties : Type 'vec' of size -1.

• Plot function (0:no or winid)
  Draw the nonlinear characteristic in a scilab window if the value of this dialog parameter is greater than zero.
  Properties : Type 'vec' of size 1.

Default properties

• always active: no
• direct-feedthrough: yes
• zero-crossing: no
• mode: no
• regular inputs:
  - port 1 : size [1,1] / type 1
  
• regular outputs:
  - port 1 : size [1,1] / type 1
  
• number/sizes of activation inputs: 0
• number/sizes of activation outputs: 0
• continuous-time state: no
• discrete-time state: no
• object discrete-time state: no
• name of computational function: tanhblk

Interfacing function

• MODNUMCOS/macros/scicos_blocks/NonLinear/VTUNE_f.sci [view code]

Computational function

• MODNUMCOS/routines/nonlinear/tanhblk.c (Type 2) [view code]

See also

• VCO_c - Discrete Voltage Controlled Oscillator block (Scicos Block)

Authors

IRCOM Group Alan Layec

Bibliography

1

S. Sancho, A. Suarez, and T. Fernandez, ``Nonlinear dynamics of microwave synthesizers. stability and noise,'' IEEE Trans. Microwave Theory Tech., vol. 49, no. 10, pp. 1792-1803, Oct. 2001.