CMET 437 Data Communication Method Spring, 2017 Home work 5 1. (5 points) Why is
ID: 3824673 • Letter: C
Question
CMET 437 Data Communication Method Spring, 2017 Home work 5 1. (5 points) Why is multiplexing so cost-effective? 2. (5 points) How is interference avoided by using frequency division multiplexing? 3. (10 points) A voice signal is sampled at 8K samples per second, 8 binary bits are transmitted for each sample value. Twenty-four voice signals are to be multiplexed and transmitted over twisted pair. What is the bandwidth required for FDM? Assuming a bandwidth efficiency of 1 bps/Hz, what is the bandwidth required for TDM using PCM? 4. (20 points) The information in four analog signals is to be multiplexed and transmitted over a telephone channel that has a 400- to 3100-Hz bandpass. Each of the analog baseband signals is bandlimited to 500 Hz. Design a communication system (block diagram) that will allow the transmission of these four sources over the telephone channel using a. Frequency division multiplexing with SSB (single sideband) subcarriers b. Time division multiplexing using PCM; assume 4-bit samples Show the block diagrams of the complete system, including the transmission, channel, and reception portions. Include the bandwidths of the signals at the various points in the systems.Explanation / Answer
Cost effectiveness of multiplexing:
Multiplexing helps different entities to share the cost of the medium or link. The resultant is a very cost effective method. For example, if we want to send two signals each of it being 50 MHz over a band of 80MHz.
There are 2 obvious ways to do this.
The first method is costly. The second method wastes a lof of the bandwidth. Since we are sending only 50 MHz signal at a time over 80MHz band, so 30 MHz of capacity is wasted.
Thus, we need to use multiplexing to get close to 100% efficiency and without the extra cost that the above two methods incur.
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