DELAYV_f

Block Screenshot

Contents

• Variable delay

• • Palette

  • Description

  • Dialog box

  • Default properties

  • Interfacing function

  • Computational function

Palette

• Discrete time systems palette

Description

The Variable Delay block can be used to simulate a variable time delay between an action and its effect. The block might be used, for example, to model a system with a pipe where the speed of a motor pumping fluid in the pipe is variable.

The block accepts two inputs and one output: the first input is the signal u(t) that passes through the block (data input); the second input is the variable time delay τ(t).

The output activation ports trigger every "Max delay"/length("Register initial condition").

The input activation port and the first output activation port are meant to be linked, to get the variations of the input.

The final delay is: τ(t) + "Max delay"/length("Register initial condition").

Dialog box

• Number of inputs

  Set the vector size of the first regular input and the vector size of the regular output port.

  Properties : Type 'vec' of size 1.

• Register initial condition

  Set the length and the initial conditions of the register.

  Properties : Type 'vec' of size -1.

• Max delay

  It defines the largest value the time delay input can have.The value cannot be negative.

  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

  - port 2 : size [1,1] / type 1

• regular outputs:

  - port 1 : size [1,1] / type 1

• number/sizes of activation inputs: 1

• number/sizes of activation outputs: 2

• continuous-time state: no

• discrete-time state: yes

• object discrete-time state: no

• name of computational function: delayv

Interfacing function

• SCI/modules/scicos_blocks/macros/Linear/DELAYV_f.sci

Computational function

• SCI/modules/scicos_blocks/src/fortran/delayv.f (Type 1)

Variable delay example

In this example, the sine function (in black) est delayed alternatively by 0 and 1 second. The amplitude of the GENSQR_f block is fixed at 2, but the "Max delay" parameter of the DELAVV_f block restrains that value to 1. We see that with every time GENSQR_f is activated (every 2*π seconds), the delay changes: the curves overlap (delay=0) and are shifted (delay=1) in turn.