DCOM PRCATICAL-QPSK

                                                    


                                                                                     

 Name of Experiment :-Experimental study of Quadrature Phase shift keying 

The Quadrature Phase Shift Keying QPSK is a variation of BPSK, and it is also a Double Side Band Suppressed Carrier DSBSC modulation scheme, which sends two bits of digital information at a time, called as bigits.

Instead of the conversion of digital bits into a series of digital stream, it converts them into bit pairs. This decreases the data bit rate to half, which allows space for the other users.

QPSK Modulator

The QPSK Modulator uses a bit-splitter, two multipliers with local oscillator, a 2-bit serial to parallel converter, and a summer circuit. Following is the block diagram for the same.

QPSK Modulator

At the modulator’s input, the message signal’s even bits (i.e., 2nd bit, 4th bit, 6th bit, etc.) and odd bits (i.e., 1st bit, 3rd bit, 5th bit, etc.) are separated by the bits splitter and are multiplied with the same carrier to generate odd BPSK (called as PSKI) and even BPSK (called as PSKQ). The PSKQ signal is anyhow phase shifted by 90° before being modulated.

The QPSK waveform for two-bits input is as follows, which shows the modulated result for different instances of binary inputs.

QPSK Waveform





 
           PRE TEST 




                                                               THEORY                     PRACTICAL

 
                                                                                                                                          POST TEST


Reference:- 














Comments

Post a Comment

Popular posts from this blog

DATA COMMUNICATION PRACTICAL-PCM

Image
TE ELECTRONICS  DATA COMMUNICATION PRACTICAL                                                                                        Introduction to Practicals   Name of Experiment :-Experimental study of Pulse Code Modulation   Modulation  is the process of varying one or more parameters of a carrier signal in accordance with the instantaneous values of the message signal. The message signal is the signal which is being transmitted for communication and the carrier signal is a high frequency signal which has no data, but is used for long distance transmission. There are many modulation techniques, which are classified according to the type of modulation employed. Of them all, the digital modulation technique used is  Pulse Code Modulation  P C M . A signal is pulse code modulated to convert its analog information into a binary sequence, i.e.,  1s  and  0s . The output of a PCM will resemble a binary sequence. The following figure shows an example of PCM output with respect to instantan
Read more

DCOM PRACTICAL -LINE CODE

Image
                                                                                                                                           Name of Experiment :-Experimental Study of Basicline codes and Multilevel line codes. A  line code  is the code used for data transmission of a digital signal over a transmission line. This process of coding is chosen so as to avoid overlap and distortion of signal such as inter-symbol interference. Properties of Line Coding Following are the properties of line coding − As the coding is done to make more bits transmit on a single signal, the bandwidth used is much reduced. For a given bandwidth, the power is efficiently used. The probability of error is much reduced. Error detection is done and the bipolar too has a correction capability. Power density is much favorable. The timing content is adequate. Long strings of  1s  and  0s  is avoided to maintain transparency.               PRE TEST                                                           
Read more

DCOM PRACTICAL-AMPLITUDE SHIFT KEYING

Image
                                                                                          Name of Experiment :-Experimental study of Amplitude shift keying  Amplitude Shift Keying  A S K A S K  is a type of Amplitude Modulation which represents the binary data in the form of variations in the amplitude of a signal. Any modulated signal has a high frequency carrier. The binary signal when ASK modulated, gives a  zero  value for  Low  input while it gives the  carrier output  for  High  input. The following figure represents ASK modulated waveform along with its input.               PRE TEST                                                                         THEORY                         PRACTICAL                                                                                                                                     POST TEST Reference:-  Manual
Read more