5 Written Questions
4 Multiple Choice Questions
- Converts digital computer signals to analog and sent over telephone lines. 3G is for sending data faster with a speed 2-3 Mbps. WiMAX is to replace DSL, Cable and cellular service with 1-4 Mbps. Satellite is very expensive because of long transmission distance. Two way data transmission is expensive. Some carriers are pushing fiber directly to the home with 100 Mbps or more.
- DAC is Digital to Analog Conversion where as ADV is Analog to Digital conversion.
- Voice traffice is fairly constant. Data traffice is short bursts with long silences. Circuit switching is not efficient with data.
- Circuit is an end-to-end connection between two subscribers. Capacity is reserved on all trunk lines and switches.
4 True/False Questions
Where are analog and digital signals used in the PSTN? → Analog is electrical signals made from pressure waves.Digital is either on or off.
What is pulse code modulation? When is it used? → 1-pair Voice Grade UTP, 2-pair data-grade UTP, and optical fiber
What is a cellular telephone cell? What functions does the mobile telephone switching office serve? → Pulse code modulation is the signal being sampled 8,000 times per second. Each sample is 1/8000 of a second. Each sample period, the amplitude of the signal is sampled. Each filter can distinguish 256 loudness levels.Produces 8 bits per sample.
Compare DSL and cable options → ADSL uses 1 VG UTP lines. Cable uses optical fiber to the neighborhood with thick coaxal cables. Thin coaxial drop cables go to the residences.