EC6501 Digital Communication Important questions
EC6501 Digital Communication Important questions regulation 2013 Anna University free download. Digital Communication EC6501 Important questions pdf free download.
Sample EC6501 Digital Communication Important questions:
Part A 2 marks
1. What is inter symbol interference in baseband binary PAM systems?
In baseband binary PAM, symbols are transmitted one after another. These symbols are separated by sufficient time durations. The transmitter, channel and receiver acts as a filter to this baseband data. Because of the filtering characteristics, transmitted PAM pulses are spread in time.
2. What are eye pattern? (ec6501 digital communication important questions)
Eye pattern is used to study the effect of ISI in baseband transmission.
1. Width of eye opening defines the interval over which the received wave can be sampled without error from ISI.
2. The sensitivity of the system to timing error is determined by the rate of closure of the eye as the sampling
time is varied. (ec6501 digital communication important questions)
3. Height of the eye opening at sampling time is called margin over noise.
3. How is eye pattern obtained on the CRO?
Eye pattern can be obtained on CRO by applying the signal to one of the input channels and given an external trigger of 1/Tb Hz. This makes one sweep of beam equal to Tb seconds.
4. What is correlative coding?
Correlative level coding is used to transmit a baseband signal with the signaling rate of 2Bo over the channel of bandwidth Bo. This is made physically possible by allowing ISI in the transmitted in controlled manner. This ISI is known to receiver. The correlative coding is implemented by duo binary signaling and modified duo
binary signaling. (ec6501 digital communication important questions)
5. Define Duo binary baseband PAM system.
Duo binary encoding reduces the maximum frequency of the baseband signal. The word duo means to double the transmission capacity of the binary system. Let the PAM signal ak represents kth bit. Then the encoder the new waveform as
Ck =ak + ak-1 Thus two successive bits are added to get encoded value of the kth bit. Hence Ck becomes a correlated signal even though ak is not correlated. This introduces intersymbol interference in the controlled manner to reduce
the bandwidth. (ec6501 digital communication important questions)
6. What are the three broad types of synchronization?
1. Carrier synchronization
2. Symbol & Bit synchronization
3. Frame synchronization. (ec6501 digital communication important questions)
| Subject Name | Digital Communication |
| Subject Code | EC6501 |
| Regulation | 2013 |
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