This document contains a problem set on digital communications from the Department of Electrical Engineering at the University of Isfahan. The problem set covers topics including source and channel coding, prefix codes, the Kraft-McMillan inequality, linear block codes, repetition codes, and error detection/correction. It contains 4 problems asking students to identify prefix codes, apply concepts like the Kraft-McMillan inequality, find encoding tables and error correction capabilities of codes, and evaluate syndromes for single and double error patterns.