continuous signal delay

I have continuous signal generated from simulink and i want to make dp = p(k)-p(k-1) where p(k) is the current and p(k-1) is the last value from last reading of simulink.

Answer 1

[Kaustubha Govind]

Feed p(k) into the Unit Delay block to get p(k-1) and subtract the latter from the former to get p(k)-p(k-1).

Answer 2

[mado]

but this unit delay is for digital and my signal is analog

[Kaustubha Govind]

Did you mean to say that Unit Delay is a discrete-time block? Yes, but in your question, you said you need p(k-1), which is a discrete-time representation.

[Kaustubha Govind]

Perhaps you need the Transport Delay block? http://www.mathworks.com/help/toolbox/simulink/slref/transportdelay.html

Answer 3

[mado]

I tried transport delay but the output of this block is zero , i don't know why

[Kaustubha Govind]

It is probably zero for the length of the delay that you've specified. Increase the simulation stop time to see if the delayed signal is eventually displayed.

[mado]

thanks , its working