Set Correlation window length sufficiently large so that the computed delay eventually stabilizes at a constant value. When this occurs, the signal from the optional chg output port stabilizes at the constant value of zero. If the computed delay is not constant, you should increase Correlation window length. If the increased value of Correlation window length exceeds the duration of the simulation, then you should also increase the duration of the simulation accordingly. If you can roughly estimate the delay, then the Correlation window length will produce a stable delay estimate at four times that value.

If the cross-correlation between the two signals is broad, then the Correlation window length value should be much larger than the expected delay, or else the algorithm might stabilize at an incorrect value. For example, a CPM signal has a broad autocorrelation, so it has a broad cross-correlation with a delayed version of itself. In this case, the Correlation window length value should be much larger than the expected delay.

If the block calculates a delay that is greater than 75 percent of the Correlation window length, the signal sRef is probably delayed relative to the signal sDel. In this case, you should switch the signal lines leading into the two input ports.

You can make the Find Delay block stop updating the delay after it computes the same delay value for a specified number of samples. To do so, select Disable recurring updates, and enter a positive integer in the Number of constant delay outputs to disable updates field. For example, if you set Number of constant delay outputs to disable updates to 20, the block will stop recalculating and updating the delay after it calculates the same value 20 times in succession. Disabling recurring updates causes the simulation to run faster after the target number of constant delays occurs.