Ask questions and take the postgraduate entrance examination. If you want to take an examination of communication in Hefei University of Technology, who knows what to read in the teaching materials of specialized courses? Do you have any good information? . (Indicate the exact publishing house. Signals and Systems, written by Ding Zhizhong (Director of Communication Department of Polytechnic University, studying the direction of communication system, not recommending his graduate students), Press, Hefei University of Technology Press. Digital signal processing, Xi 'an University of Electronic Science and Technology Press, takes these two specialized courses in the initial test. This is a textbook for our undergraduate course. I am a junior at school.