*Question E7F04:
Which method generates an SSB signal using digital signal processing?*  

*Correct Answer is  D: Signals are combined in quadrature phase relationship*  

### AI Response: (may contain errors)  

To generate a Single Sideband (SSB) signal using digital signal processing (DSP), the correct method involves combining signals in a quadrature phase relationship. Let's break down why this is the correct answer and why the other choices are incorrect:

### Correct Answer: D

**Signals are combined in quadrature phase relationship**

- **Explanation**: In DSP, generating an SSB signal often involves using a technique called the "Hilbert Transform" to create a 90-degree phase shift. This results in two signals that are in quadrature (i.e., 90 degrees out of phase). These signals are then combined to cancel out one of the sidebands, leaving only the desired sideband. This method is efficient and precise in the digital domain.

### Incorrect Answers:

**A: Mixing products are converted to voltages and subtracted by adder circuits**

- **Explanation**: This method describes an analog approach to SSB generation, such as the phasing method, but it does not specifically involve digital signal processing. DSP typically uses mathematical operations rather than physical adder circuits.

**B: A frequency synthesizer removes unwanted sidebands**

- **Explanation**: A frequency synthesizer is used to generate precise frequencies but does not inherently remove sidebands. Removing sidebands is a function of filtering or phasing, not frequency synthesis.

**C: Varying quartz crystal characteristics are emulated in digital form**

- **Explanation**: Quartz crystals are used in oscillators for frequency stability, but emulating their characteristics digitally does not directly relate to SSB generation. This choice does not address the process of sideband suppression.

### Key Concept:

- **Quadrature Phase Relationship**: In DSP, creating a quadrature phase relationship is crucial for SSB generation. By shifting one signal by 90 degrees and combining it with the original, you can effectively cancel out one sideband, achieving the desired SSB output.

Understanding these concepts will help you recognize the correct method for generating SSB signals using digital signal processing.