 principal cause of systematic phase jitter is a function of What value BER can we expect as a mean for the North American digital network? 25. What is the threshold BER for the digital network? Why is it set at that point? Give at least three "economic" advantages of digital switching. Define the function of a time-slot interchanger. If we have a switch that is only a single time-slot interchanger for an E1 system, how many different subscribers could I be connected to? What are the three functional blocks of a conventional time-slot interchanger (i.e., a time switch)? 30. How can the capacity of a time-slot interchanger be increased? Give two methods. 31. How can a switch manufacturer sell just one switch to cover both E1 and DS1 regimes? 32. What is the function of a junctor in a digital switch? What are the two primary factors that can change a national digital network structure? What causes a slip on a digital network? What is the difference between controlled slips and uncontrolled slips? 36. Argue the efficacy of using an external timing source to synchronize network elements. What is a disciplined oscillator? What is holdover stability? 39. According to CCITT, if we can maintain long-term frequency departure to better than 1 X 10-11, what kind of slip performance can we expect? 40. Define a burst errored second. 41. What kind of slip rate could we expect if all network timing references were lost? REFERENCES 1. IEEE Standard Dictionary of Electrical and Electronic Terms, 6th ed., IEEE Std. 100-1996, IEEE, New York, 1996. 2. Reference Data for Radio Engineering, 5th ed., ITT, Howard W. Sams, Indianapolis, IN, 1968. 3. J. Bellamy, Digital Telephony, Wiley, New York, 1991. 4. D. R. Smith, Digital Transmission Systems, 2nd ed., Van Nostrand Reinhold, New York, 1993. 5. Transmission Systems for Communications, 5th ed., Bell Telephone Laboratories, Holmdel, NJ, 1982. REFERENCES 6. Second Order Digital Multiplex Equipment Operating at 8448 kbps Using Positive/Zero/Negative Justification, CCITT Rec. G.745, Fascic