The difference about QPSK, BPSK and 16-QAM in spectrum

1. What is the difference between QPSK and BPSK?
2. What is BPSK spectrum?
3. Why is QPSK and BPSK the same?

What is the difference between QPSK and BPSK?

Two common examples are "binary phase-shift keying" (BPSK) which uses two phases, and "quadrature phase-shift keying" (QPSK) which uses four phases, although any number of phases may be used.

What is BPSK spectrum?

Convolution of any spectrum with a frequency impulse centers this spectrum about the frequency of the impulse. Therefore, the BPSK spec- trum is the spectrum of the baseband symbols, centered about the carrier frequency. The spectrum of the baseband symbols is rather complicated.

Why is QPSK and BPSK the same?

The probability of error is identical for BPSK and QPSK because the BER has been measured in terms of signal to noise ratio per bit.