PDF Drive is your search engine for PDF files. As of today we have 78,, eBooks for you to download for free. No annoying ads, no download limits, enjoy . Modern digital and analog communication systems / B. P. Lothi, Zhi Ding.—4th ed. p. Eºrl. iSBN Browse's Introduction to the Symptoms & Signs of Surgical. PDF | I am extremely happy to present the book ''Analog and Digital Communication'' as per the revised syllabus (R) of Anna University.
|Language:||English, Spanish, Arabic|
|Genre:||Fiction & Literature|
|Distribution:||Free* [*Registration Required]|
How to Use the Book The book can be used for an introductory course on analog and digital communications in different ways, depending on the background of. Download An Introduction to Analog and Digital Communication By Simon Haykin, Michael Moher – The second edition of this accessible book provides. This book will help students, irrespective of their level of study, to grasp the fundamental aspects of electronic communication by starting from the basics and .
Normally, this synchronization information consists of 1 bit per frame, alternating between 0 and 1. Each source places its data to the link only when the corresponding slot arrives. In synchronous TDM, if a device does not have data to send, then its time slots remain empty. The transmission of data with synchronous TDM is shown in Figure 9. Figure 9. Synchronous TDM transmission representation. The capacity of the transmission link must be higher than the total capacity of input lines.
It is very complex to implement. It dynamically allocates the time slots on the demand to separate input channels, thus saving the channel capacity. Here the time slots are flexible, and the total capacity of input lines can be greater than the link capacity of the channel. In synchronous TDM if there are n input lines, there must be n time slots, but in asynchronous TDM if we have n input lines, then the frame may contain less than n slots.
Here the number of slots in a frame is based on a statistical analysis of the number of input lines.
The transmission of data with asynchronous TDM is shown in Figure Figure Data transmission with asynchronous TDM. An output slot in synchronous TDM is totally occupied by data, in statistical TDM; a slot needs to carry data as well as the address of the destination. It requires buffer, and address information is needed as there is no separate slots assigned for each user.
It uses spread-spectrum communication, and a narrowband signal is spread over a large band of frequency; it allows multiple signals from multiple users to share a common communication channel. CDM involves the modulation of data with this spreading code in the transmitter side. The receiver also wants to know the same code used at the transmitter side in order to decode the signal at the receiving side.
Here different random sequences correspond to different communication channels from different stations. To separate other channels, CDM assigns each channel with its own code. The main advantage of CDM is protection from interference and tapping because only the sender and the receiver know the spreading code Figure CDM is widely used in second-generation and third-generation wireless communication network.
In CDM more number of users can share the same bandwidth. It is scalable. It is well-matched with other cellular technologies. Interference is reduced because different code words are allocated to each user. Efficient utilization of fixed frequency spectrum.
As the number of users increases, the overall quality of services decreases. More complex system and primarily it is used in wireless transmission.
It is a multicarrier modulation scheme. Now it is used in 4G broadband communication system and next-generation systems. OFDM is popular in broadband wireless systems due to its resistance to multipath fading. OFDM has high data rate capability with reasonable computational complexity. OFDM divides a broadband channel into multiple parallel narrowband subchannels, and each channel carries a low data rate stream of signals.
Finally these signals are summing and then transmit as a high data rate stream. In an OFDM transmitter, the input signal bits are mapped into a bank of quadrature amplitude modulator which encodes these into complex symbols.
This is fed to an inverse fast Fourier transform IFFT to ensure the orthogonality of the subchannels.
This output is converted into parallel to serial, modulated into a carrier wave, and then transmitted into the air.
At the receiver the reverse process is performed for recovering the original signal. The advantages of OFDM are that its low computational complexity because OFDM may be viewed as a many slowly modulated narrowband signals rather than a rapidly modulated wideband signal.
For OFDM transmitter, a serial stream of binary digits is considered as the input. The input is converted into N parallel streams using inverse multiplexing. The transformation of N parallel streams into the state-space mechanism is performed by means of modulation techniques like quadrature amplitude modulation QAM and phase shift keying PSK.
OFDM transmitter. A digital modulation system for data communication by varying or modulating the phase of the reference signal or the carrier wave signal is known as PSK.
A finite number of phases is involved in PSK with each phase having a distinctive pattern of binary digits. An integration of trouble-free AM and simple phase modulation is called QAM in which the large amount of data is transmitted over the same bandwidth due to the synergistic effect of simple amplitude modulation and phase modulation.
Hence, QAM increases the efficiency of data transmission for radio communication systems Figure OFDM transmitter simple block diagram. Later, the time-domain samples are quadrature mixed to passband in the normal way. By the use of digital-to-analog converters DACs , the real and imaginary components are primarily converted to the analog domain.
Such analog signal helps to modulate corresponding cosine and sine waves at the carrier frequency. Finally, those signals are summed up to provide the transmission signal. The transmitter-generated signal is further transmitted over the channel for receiving.
The receiver receives the baseband OFDM signals, and then it passes through a low-pass filter to remove the unwanted signals. The baseband signals are then sampled and digitized using ADCs, and a forward FFT is used to convert back to the frequency domain. By means of an appropriate symbol detector, the frequency domain signals are converted to N parallel streams, and each stream is converted to a binary stream.
A sequential stream combining all binary stream acts as an estimate of the original binary stream at the transmitter side. OFDM signal is robust and more tolerant in multipath propagation environment to delay spread. OFDM is more resistant to frequency selective fading than single carrier transmission systems. OFDM system gives good protection against co-channel interference and impulsive parasitic noise.
OFDM system uses pilot subcarriers to prevent the frequency and phase shift errors. OFDM system has also certain limitations rather than the abovementioned potential capabilities.
OFDM is very sensitive to carrier frequency offset and hence becomes difficult to synchronize during sharing of subcarriers different transmitters.
Digital multiplexer Digital multiplexer [ 6 , 7 , 8 ] or data selector is a logic circuit that has several input lines and a single output line. It also consists of data selector switch which is used to select the inputs and permit the data into the device to output. Circuit diagram of four-in-one multiplexer. Here D0, D1, D2, and D3 are data input lines. S0 and S1 are data selector or logic switches. Thus the data from D0 line is outputted through this AND gate.
At that time the other gates are in 0 output position. Check your Email after Joining and Confirm your mail id to get updates alerts.
Other Usefu l Links. Your Comments About This Post. Is our service is satisfied, Anything want to say? Cancel reply. Please enter your comment! Please enter your name here. You have entered an incorrect email address!
Get New Updates Email Alerts Enter your email address to subscribe this blog and receive notifications of new posts by email. Join With us. Today Updates.
Statics and Dynamics By R. Hibbeler Book April Punmia, Ashok Kumar Jain, Arun April 8. April 7. Popular Files. January June 2. Trending on EasyEngineering.
October Lindeburg PE Book December Freeman Book Free Download August Never Miss. Load more. Sponsored By. Sharing is Caring.
About Welcome to EasyEngineering, One of the trusted educational blog. Get New Updates Email Alerts Enter your email address to subscribe to this blog and receive notifications of new posts by email.
Search Your Files.