Simulink: rectangular pulse filter with finite rise time?

Is there a way to create a rectangular pulse with finite rise time in Simulink? I found the "Ideal Rectangular Pulse Filter" in the Communications Blockset. But that one gives inifite rise time, basically the same as if doing a pure rate transition.

Many thanks!!!

Answer 1

[Paulo Silva]

I found how to generate square waves with slew rate, do this:

Signal Generator -> Rate Limiter

[Fangjun Jiang]

Nice!

[Cathy]

this works beautifully! thanks a lot~ \\bow

Answer 2

[Arnaud Miege]

Or filter the ideal pulse generated from say the Pulse Generator block with a first order low-pass filter using the Transfer Fcn or Discrete Transfer Fcn block.

Arnaud

[Paulo Silva]

+1 vote but I wonder why simulink doesn't have a block for that purpose or just add another parameter to the square wave generation.

[Arnaud Miege]

Good point. Maybe worth raising an enhancement request?

http://www.mathworks.com/support/service_requests/contact_support.do

[Paulo Silva]

I submited this request: There's no easy way to generate square waves with specific rise time (Slew rate), the signal generators should have another parameter for the rise time (and also fall time) because that would be similar to real world square waves.

Answer 3

[Paulo Silva]

Use the Signal builder from simulink

    _   _        _   _
  _| |_| |_ -> _/ \_/ \_

[Fangjun Jiang]

Paulo, I don't she is asking about the pulse generator.

[Paulo Silva]

The question is interesting because simulink apparently lacks the parameter for the Slew Rate.

[Fangjun Jiang]

If it is just the need to generate a pulse with slew rate, I guess the "Repeating Sequence" block can do the job.

Answer 4

[Fangjun Jiang]

I thought Cathy was asking for a filter, not a source block to generate square pulse or pulse with slew rate. Check out this Ideal Rectangular Pulse Filter. It talks about upsampling which I have no knowledge. Is there a similar filter that represents non-square pulse sampling that has different filtering effect?

Answer 5

[Cathy]

thank you all! is there a way to create a customized filter for this purpose? i was able to get a workaround in Matlab:

y = rcosflt(x, Fd, Fs,'filter', pulse_slewrate);

is there a similar way to do this in Simulink? thanks!!

Answer 6

[Fangjun Jiang]

This Raised Cosine Transmit Filter?