Study of PSK Modulation and Demodulation

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Experiment Name

Study of PSK Modulation and Demodulation

 

Theory

Phase Shift Keying (PSK) is a digital modulation technique where the phase of a carrier signal is changed according to the digital data being transmitted. There are several types of PSK, including Binary Phase Shift Keying (BPSK) and Quadrature Phase Shift Keying (QPSK), with BPSK being the simplest form.

Modulation is the process of varying a carrier signal to transmit data, while demodulation is the process of extracting the original information from the modulated carrier signal.

In PSK, the binary data (1s and 0s) are used to shift the phase of the carrier signal by 0 or 180 degrees. During demodulation, the received signal is correlated with a reference signal to retrieve the transmitted binary data.

  

Apparatus

Signal generator

PSK modulator and demodulator

Oscilloscope

Function generator

Data acquisition system or PC with data processing software

Connecting cables and probes


Circuit Diagram:




Procedure

Modulation

 Connect the signal generator to the PSK modulator input.

Set the signal generator to output a sine wave at the desired carrier frequency.

Connect the binary data source to the modulator input. This could be a pre-programmed data pattern or a live data stream.

Observe the output of the PSK modulator using an oscilloscope. Ensure that the phase of the carrier signal changes according to the binary data input.

Demodulation

Connect the output of the PSK modulator to the PSK demodulator input.

Ensure the demodulator has access to the same carrier frequency and phase reference as used in modulation.

Connect the demodulator output to the data acquisition system or oscilloscope.

 Observe the demodulated signal and verify that it matches the original binary data input.



Results

PSK Modulation and Demodulation

On the oscilloscope, the PSK modulated signal shows phase shifts of 180 degrees corresponding to the binary data input. 

The demodulated signal successfully recovers the original binary data, indicating accurate phase detection.

The PSK modulated signal shows phase shifts of 0, 90, 180, and 270 degrees, corresponding to the bit pairs of the input data. 

 The demodulated signal accurately recovers the bit pairs, confirming correct phase shift interpretation.

 

Discussion

The experiment successfully demonstrated the principles of PSK modulation and demodulation. Key observations include:

The phase of the carrier signal shifts between 0 and 180 degrees, effectively encoding the binary data.

The carrier phase changes to one of four distinct values, representing two bits per symbol, enhancing data transmission efficiency




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এই ব্লগটি থেকে জনপ্রিয় পোস্টগুলি

Assembly LAB: Character Input Output

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 .model small .stack 100h .data  ms db 'Enter A Character: $' .code main proc     mov ax, @data     mov ds, ax          mov ah, 9     lea dx, ms     int 21h                mov ah, 2     mov dl, 10     int 21h     mov dl, 13     int 21h          mov ah, 1     int 21h     mov bl, al          mov ah, 2     mov dl, 10     int 21h     mov dl, 13     int 21h          mov ah, 2     mov dl,bl     int 21h          exit:     mov ah, 4ch     int 21h     main endp end main
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Assembly LAB: Print Alphabet(A-Z)

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 .MODEL SMALL  .STACK 100H    .DATA     PROMPT  DB  'The Alphabets are : $'    .CODE    MAIN PROC      MOV AX, @DATA                ; initialize DS      MOV DS, AX        LEA DX, PROMPT               ; load and print PROMPT      MOV AH, 9      INT 21H        MOV CX, 26                  ; initialize CX        MOV AH, 2                    ; set output function      MOV DL, 41H                    ; initialize DL with 0        @LOOP:                       ; loop label        INT 2...
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