Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
Paper format. National Examinations, May 2019 — 16-Elec-B3 Digital Communications Systems. Closed book, 3 hours; one approved Casio or Sharp calculator. Five questions of 25 marks each; the cover page states that any four constitute a complete paper worth 100 marks, and that only the first four appearing in the answer book are marked. All five are solved here, because this set is a study resource rather than a sitting.
Reference texts. S. Haykin, Communication Systems, 5th ed. (Wiley) — noise, link budgets, digital detection; B. P. Lathi & Z. Ding, Modern Digital and Analog Communication Systems, 4th ed. (Oxford) — sampling, PCM, source and channel coding, spread spectrum; A. V. Oppenheim & A. S. Willsky, Signals and Systems, 2nd ed. (Pearson) — the sampling theorem and aliasing; J. G. Proakis & D. G. Manolakis, Digital Signal Processing, 4th ed. (Pearson) — quantization and A/D conversion. Canadian spectrum practice for the spread-spectrum question follows ISED Canada RSS-247 (digital transmission systems, frequency-hopping systems and licence-exempt local area network devices).
Source note. The tiles were reassembled from the PDF's own image objects, which recovers a clean full-resolution raster of all three pages. Where a printed phrase admits more than one engineering reading, the reading used is stated explicitly in a check callout.
