Description:  The book covers DOEACC Syllabus for A9 Paper) and describes asynchronous, synchronous data, multiplexers and data transmission modes in a very simple manner. It also deals with introduction o radio, VHF, Microwave VSAT and satellite communication links.  Data modem, multichannel data communication and pulse code modulation are dealt in detail. Data networks and topology  both logical and physical are described with large number of illustrations and examples for ease of understanding.  Features :  Communication systems and satellite application described in easy to understand language  Detailed exposition of error correction codes and Hamming codeOSI 7-Layer model and data communication protocols effectively illustrated with examples Special features of high speed modems based on QAM principle described completely Each chapter contains solutions to test paper for practice and self evaluation Glossary of most frequently used terms provided for ready reference. comprehensive index included for easy access to numerous terms needed for answering objective questions set in 'A' level examination. Contents Part 1- Data Communication and Networking Essentials Chapter 1- Data Communication Chapter 2- Transmission Media Chapter 3- Data Modems Chapter 4- Multichannel Data Communication Chapter 5- Data Networks Chapter 6-Network Protocols Chapter 7- Fibre Optic Communications Chapter 8- Data Communication Systems