*Question E7H13:
Which of the following is a technique for providing highly accurate and stable oscillators needed for microwave transmission and reception?*  

*Correct Answer is  D: All these choices are correct*  

### AI Response: (may contain errors)  

To ensure highly accurate and stable oscillators for microwave transmission and reception, several techniques can be employed. Let's explore each option:

1. **Use a GPS signal reference**:  
   - GPS signals are highly accurate and stable because they are synchronized with atomic clocks on satellites. By using a GPS signal as a reference, an oscillator can achieve high precision and stability.

2. **Use a rubidium stabilized reference oscillator**:  
   - Rubidium oscillators are a type of atomic clock that provide excellent frequency stability. They are commonly used in applications requiring precise timing and frequency control.

3. **Use a temperature-controlled high Q dielectric resonator**:  
   - A high Q (quality factor) dielectric resonator is used to maintain frequency stability. By controlling the temperature, the resonator's frequency drift due to temperature changes is minimized, enhancing stability.

**Correct Answer: D: All these choices are correct**

- Each of these techniques independently provides a method to achieve the desired accuracy and stability in oscillators for microwave applications. Therefore, the correct answer is that all these choices are correct.

**Why the other choices are incorrect:**

- In this case, none of the individual choices (A, B, or C) are incorrect. Each one is a valid technique for achieving the goal of a highly accurate and stable oscillator. The question is designed to test your understanding that multiple methods can be used to achieve the same objective.