Compare the BPSK and BFSK modulation schemes. Also, explain the generation of BPSK and BFSK signals.

Comparison of BPSK and BFSK Modulation Schemes:

1. Modulation Technique:

• BPSK (Binary Phase Shift Keying): BPSK is a digital modulation technique where the information is encoded by shifting the phase of a carrier signal between two discrete values, typically 0 and 180 degrees.

• BFSK (Binary Frequency Shift Keying): BFSK is a digital modulation technique where the information is encoded by shifting the frequency of a carrier signal between two discrete values.

2. Signal Representation:

• BPSK: In BPSK, the binary data is represented by two distinct phase values of the carrier signal. The phase shift is typically 180 degrees, resulting in two possible signal states:

0: Carrier signal with a phase shift of 0 degrees
1: Carrier signal with a phase shift of 180 degrees

• BFSK: In BFSK, the binary data is represented by two distinct frequency values of the carrier signal. The frequency shift is typically a fixed amount away from the center frequency. The two possible signal states are:

0: Carrier signal with a frequency of f1
1: Carrier signal with a frequency of f2

3. Bandwidth Requirements:

• BPSK: BPSK has a bandwidth requirement of approximately twice the symbol rate (bit rate).

• BFSK: BFSK has a bandwidth requirement of approximately twice the frequency deviation.

4. Signal Detection:

• BPSK: BPSK signals are typically detected using a phase-locked loop (PLL) or a correlation receiver. The PLL tracks the phase of the received signal and compares it to a reference phase to determine the transmitted data.

• BFSK: BFSK signals are typically detected using a frequency discriminator or a matched filter. The frequency discriminator measures the frequency of the received signal and compares it to a reference frequency to determine the transmitted data.

Generation of BPSK and BFSK Signals:

1. BPSK Signal Generation:

• A BPSK signal can be generated using a phase modulator. The phase modulator shifts the phase of the carrier signal by 180 degrees depending on the input binary data.

• Another method for generating a BPSK signal is to use a quadrature modulator. The quadrature modulator takes two input signals: the in-phase (I) signal and the quadrature (Q) signal. The I signal is modulated with the binary data, and the Q signal is set to zero. The output of the quadrature modulator is a BPSK signal.

2. BFSK Signal Generation:

• A BFSK signal can be generated using a frequency modulator. The frequency modulator shifts the frequency of the carrier signal depending on the input binary data.

• Another method for generating a BFSK signal is to use a voltage-controlled oscillator (VCO). The VCO is tuned to a center frequency, and the input binary data is used to control the tuning voltage of the VCO. This causes the frequency of the VCO to shift between two discrete values, resulting in a BFSK signal.