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Increasing step response length for ChannelSim

Question asked by PavleM on Aug 30, 2010
Using ADS 2009U1, I am trying to run ChannelSim on various channels (modeled with multilayer coupled microstrip segment elements and/or their S-parameters).

In some cases, I have noticed that the step response used for ChannelSim convolution seems to be truncated too early - there is a clear reflection at the receiver due to impedance mismatch, however the step response simulation is stopped much before the response can settle (not waiting for the channel round-trip time to capture higher-order reflections). See attached screenshots - two exact same channels with slightly different terminations, producing vastly different results.

I have tried increasing convolution tolerance to strict and increasing the max impulse response length (even though the channel is only tens of bits long), but with no luck. Are there any other advanced options I can try? I don't think I have the access to the "How Convolution Computes an Impulse Response" document from the Agilent Support website, referenced in an old message.