Quadrature Phase Shift Keying

Represent 2 bits using 4 phases, doubling spectral efficiency

Real-World Applications

Satellite TV (DVB-S), 3G mobile communications (WCDMA/CDMA2000), and cable TV modem uplinks. QPSK provides the best balance of bandwidth efficiency and noise resistance, a "jack of all trades" in modern communications.

Experiment Steps

Gray Coding: Adjacent phases differ by only 1 bit
Constellation: 4 points at 45°/135°/225°/315°

Simulation Experiment

Time Domain (X: Time, Y: Amplitude)

Spectrum Analysis (X: Frequency, Y: Amplitude)

Bit Stream Analysis

Bit Stream AnalysisBER = 0.0000 (0.00%)

If BER is too high, try increasing SNR

Parameters(Real-time)

Carrier Freq500 Hz

Symbol Rate100 Baud

Eb/N010 dB

Functions: models.phy.generateQAMConstellation(), models.phy.qamModulate()

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