QPSK Receiver

QPSK Receiver Integrate & Dump MF 2 stufiger Prozess

Phasor diagram We can represent the BPSK signal using a phasor diagram which shows the two possible BPSK states. This is referred to as a signal constellation. 90˚ 180˚ = binary 0 0˚ = binary 1 180˚ 0˚ 270˚

Noise effects - BPSK 0˚ 180˚ 90˚ 270˚ 20 dB SNR 10 dB SNR 90˚ 0˚ 180˚

QPSK Receiver

M-ary PSK In order to increase the data rate without increasing bandwidth, we can further increase the number of bits per symbol. In the 8-PSK constellation below, 8 possible phase shifts allow 3 bits to be transmitted by each symbol. 0˚ = binary 000 45˚ = binary 001 90˚ = binary 011 315˚ = binary 100 270˚ = binary 101 135˚ = binary 010 180˚ = binary 110 225˚ = binary 111 0˚ 180˚ 90˚ 270˚

Noise effects (8-PSK) What is the relative likelihood of an error? 0˚ 180˚ 90˚ 270˚ 10 dB SNR What is the relative likelihood of an error?

Squaring loop Recover frequency using squaring Lowpass Filter Squaring Device Bandpass Limiter (or PLL) Frequency Divider

Costas Loop 180 Grad Unsicherheit engl. „Phase Ambiguity“ Bekannte Präambel notwendig

Costas loop Goal of Costas loop: e0 Baseband LPF VCO -90 Phase shift