upsample - Upsample discrete-time LTI systems

Syntax

sysl = upsample(sys,L)

Description

sysl = upsample(sys,L) resamples the discrete-time LTI model sys at a sampling rate that is L-times faster than the sampling time of sys (Ts₀). L must be a positive integer. When sys is a TF model, H(z), upsample returns sysl as H(z^L) with the sampling time Ts₀ / L.

The responses of models sys and sysl have the following similarities:

The time responses of sys and sysl match at multiples of Ts₀.
The frequency responses of sys and sysl match up to the Nyquist frequency π / Ts₀.

Note sysl has L times as many states as sys.

Example

Create a transfer function with a sampling time that is 14 times faster than that of the following transfer function:

sys = tf(0.75,[1 10 2],2.25)

Transfer function:
     0.75
--------------
z^2 + 10 z + 2

Sampling time: 2.25

To create the upsampled transfer function sys1, type the following commands:

L=14;
sys1 = upsample(sys,L)

These commands return the result:

Transfer function:
       0.75
------------------
z^28 + 10 z^14 + 2

Sampling time: 0.16071

The sampling time of sys1 is 0.16071 seconds, which is 14 times faster than the 2.25 second sampling time of sys.

upsample - Upsample discrete-time LTI systems

Syntax

Description

Example

See Also

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