2- The specification of two telephone links are Link Class 1 B 300-3400 Hz SNR 40 dB Class 2 600-2800 Hz 30 dB A company has a requirement to send data over a telephone link at bit rate R= 20 Kbps without error. Would you advise the company to rent the more expensive class 1 service, or the cheaper class 2 service? Justify your decision.

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Q4/ Why the performance of multimode graded index is better than multimode step index? Q5/ Design fiber optics communication system with analogue input and then measure the performance of the three types of fiber optics configurations. After that, answer the following questions: 1. Which configuration is the better? Comment! 2. Which parameters that improve the performance of multimode step index? Comment! 3. Which parameters that improve the performance of multimode graded index? Comment! 4. Which parameters that improve the performance of single mode step index? Comment! 5. If we need to increase the fiber length from 1 km to 15 km. which configuration is used? Comment!

The following data are transmitted in a serial communication system (P is the parity bit). What parity is being used in each case? a. ABCDEFGHP = 010000101 b. ABCDEFGHP = 011000101 c. ABCDP = 01101 d. ABCDEP = 101011 e. ABCDEP = 111011