B INARY P HASE S HIFT K EYING (BPSK) & Q UADRI P HASE S HIFT K EYING (QPSK)

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Transcript of B INARY P HASE S HIFT K EYING (BPSK) & Q UADRI P HASE S HIFT K EYING (QPSK)

Binary Phase Shift Keying (BPSK) & Quadri Phase Shift Keying (QPSK)

Binary Phase Shift Keying (BPSK)&Quadri Phase Shift Keying (QPSK)Binary Phase Shift Keying (BPSK)The BPSK signal is generated as:

The transmitted signals are:

- -

Illustration of BPSK

Note: Bits 1 and 0 have the same amplitude and frequency but they differ in phase.Frequency Spectrum of BPSK SignalNote : The spectrum of the binary BSK resemblesthat of double sideband suppressed carrier modulation.

BPSK DemodulatorThe detection of BPSK is achieved by:

XOR-gate

Low pass filter ( LPF)

Quadri - Phase Shift Keying (QPSK)In QPSK, the phase of the carrier takes on one of four equally spaced values such as /4, 3/4, 5/4, 7/4 or 0,/2, , 3/4.

The transmitted signal is:

Generation of QPSK SignalsSignal space representation

- si(t) can be expressed as:

Constellation Diagram

Illustration of QPSKQuadri means 4 messages are to be transmitted. Hence, 2 bits are needed to present each message

Detection of QPSKOptimum Receiver:

Examples on M-ary Constellation Diagrams

M-ary PSK Versus BPSKM-ary PSK requires more complexity in thedecision-making process.

M-ary PSK requires more transmitted power.