I am using Matlab Simulink to analyse Amplitude Modulation in Noise. I attached my system below.


My problems:

1)In the mixer I am using a bandpass filter and another one after the envelope detector and I need to determine the minimum and maximum frequencies allowed depending on these parameters( I attached screenshots too) since I tried using mathwork site but it was not helpful regarding these values. filter after envelope filter in mixer

2)Also I need to know what needs to be changed in the model if the AM channel has a different carrier frequency.

3)What does 999e3 evaluate to?

Thanks a lot!


1 Answer 1


1) Do I fail to understand the question? The allowed frequency range of a bandpass filter goes from Fpass1 to Fpass2. The range between Fstop1 and Fpass1 and from Fpass2 to Fstop2 is the transition range where the filter goes from fully attenuated to fully "open" so there shouldn't be any strong interferers in this range.

2) Your band select filter before the down-mixer. It usually has your carrier frequency in the middle of Fpass1 and Fpass2 and is as wide as your expected signal is.

3) 999000

  • $\begingroup$ Thanks for your answer it was really helpful! Just for question 1) I need to find the minimum and maximum frequencies allowed for each value in the filters and I do not know how $\endgroup$ Mar 29, 2014 at 13:02

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