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All computer network Interview Questions
21.Define bit rate and bit interval?
Ans: Digital signals are aperiodic.so instead of using period and frequency we use bit interval and bit rate respectively.Bit interval is the time required to send one single bit.Bit rate is the number of bit intervals per second.
22.What is Nyquist bit rate formula?
Ans: For a noiseless channel, the Nyquist bit rate formula defines the theoretical maximum bit rate
Bitrate=2* Bandwidth*log2L
Where Bandwidth is the bandwidth of the channel
L is the number of signal level used to represent the data
Bitrate is the bit rate in bits per second.
23.Define Shannon Capacity?
Ans: Shannon Capacity determines the theoretical highest data rate foe a noise channel.
Capacity= Bandwidth * log2 (1+SNR)
Bandwidth is the bandwidth of the channel.
SNR is the signal to noise ratio, it is the statical ratio of the power of the signal to the power of the noise.
Capacity is the capacity of the channel in bits per second
24.What is sampling?
Ans: It is the process of obtaining amplitude of a signal at regular intervals.
25.Define pulse amplitude modulation?
Ans: It is an analog to digital conversion method which takes analog signals, samples it and generates a series of pulse based on the results of the sampling. It is not used in data communication because the series of pulses generated still of any amplitude. To modify it we use pulse code modulation.
26.Define pulse code modulation?
Ans: Pulse code Modulation modifies pulses created by PAM to create a completely digital signal.
For this PCM first quantizes the PAM pulse. Quantization is the method of assigning integral values in a specific tange to sampled instances.PCM is made up of four separate processes: PAM, quantization, binary encoding and line encoding.
27.What is Nyquist Theorem?
Ans: According to this theorem, the sampling rate must be at least 2 times the highest frequency of the original signal.
28.What are the modes of data transmission?
Ans: Data transmission can be serial or parallel in mode
In parallel transmission, a group of bits is sent simultaneously, with each bit on a separate line.In serial transmission there is only one line and the bits are sent sequentially.
29.What is Asynchronous mode of data transmission?
Ans: It is a serial mode of transmission.
In this mode of transmission, each byte is framed with a start bit and a stop bit. There may be a variable length gap between each byte.
30.What is Synchronous mode of data transmission?
Ans: It is a serial mode of transmission.In this mode of transmission, bits are sent in a continuous stream without start and stop bit and without gaps between bytes. Regrouping the bits into meaningful bytes is the responsibility of the receiver.
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