In binary phase shift keying (BPSK) modulation scheme, the phase of a carrier is changed in accordance with the digital pulse signals. BPSK modulator is basically a phase modulator. Here the transmitted signal is a sinusoid of fixed amplitude. It has one fixed phase when the data is at one level and when the data is at the other level, phase is shifted by 180 degree. Binary phase shift keying method has variety of applications in digital communications systems such as the wireless LAN standard, IEEE 802.11, digital modems, wireless telephone networks etc.
Differential phase shift keying (DPSK) is an other type of phase shift keying technique which depends on the difference between successive phases. DPSK is significantly simpler to implement than ordinary PSK , since there is no need for the demodulator to have a copy of the reference signal to determine the exact phase of the received signal (it is a non coherent scheme). Here is the practical circuit of BPSK, it is build around CD4016 and 741 Op amp.
Also read: Binary Amplitude Shift Keying(BASK)
Differential phase shift keying (DPSK) is an other type of phase shift keying technique which depends on the difference between successive phases. DPSK is significantly simpler to implement than ordinary PSK , since there is no need for the demodulator to have a copy of the reference signal to determine the exact phase of the received signal (it is a non coherent scheme). Here is the practical circuit of BPSK, it is build around CD4016 and 741 Op amp.
Also read: Binary Amplitude Shift Keying(BASK)
BPSK Circuit Diagram
Components Required
- Resistors (10kΩ)
- 741 Op Amp
- CD 4016 IC
- Not Gate 7404
PSK Output Waveform
Working
- An Op amp inverting amplifier with gain 1 is used to invert the phase of the input sine wave.
- Sine wave can be obtained from a function generator or by using a RC phase shift oscillator.
- Two switches inside the quad analog switch CD 4016 are used in the circuit.When the enable input of one gate is high, the input will appear at the output.
- When the binary data is 1, sine wave is switched to output because the sine wave is connected to 1st switch and the binary data is applied to enable pin (13th pin) of 1st switch.
- When binary data is 0, the 1st switch is disabled and 2nd switch is enabled using NOT gate arrangement. Thus we get an inverted sine at the output.
- The output pins of both first and second switches are shorted and the output is taken from it. The block diagram is self explanatory.
Components Pin out
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Nice explnatn of the circuit..thanks
ReplyDeleteit doesn't work properly. because the sin wave and digital binary is not synchronized. the bit duration should be as same as sin wave period and also they should begin and end as same time.
ReplyDeleteThere is no scope of synchronization. It's only an analog switch.
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