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In this paper we provide the details of a final project in digital communications, used in a signal processing first course taught to second year ECE students. Simple nulling filters are used to minimize a sinusoidal jamming signal. The students have already learned about an FIR nulling filter, the placement of zeros on the unit circle, and the frequency response. In the filter design the students learn that the filter also removes a portion of the signal, and that increases the probability of making a bit error when noise is present. An IIR notch filter works well too, but it has parameters that are sensitive to coefficient quantization. Jammer frequency error is another constraint. The students thus find themselves in the midst of a constrained optimization problem. Students have enjoyed this project, and in particular are very eager to strive for the best bit error probability (BEP) performance.