*Question E4B01:
Which of the following factors most affects the accuracy of a frequency counter?*  

*Correct Answer is  B: Time base accuracy*  

### AI Response: (may contain errors)  

The accuracy of a frequency counter is primarily determined by the accuracy of its time base. Here's why:

1. **Correct Answer: Time base accuracy (B)**
   - The time base in a frequency counter is a highly stable oscillator that provides the reference time interval for counting cycles of the input signal. The accuracy of this oscillator directly affects the frequency measurement. If the time base is inaccurate, the frequency counter will not measure the frequency correctly, regardless of how well other components function.

2. **Why the other choices are incorrect:**
   - **Input attenuator accuracy (A):** The input attenuator is used to reduce the amplitude of the input signal to a suitable level for the counter. While important for preventing damage and ensuring proper operation, it does not affect the frequency measurement accuracy.
   - **Decade divider accuracy (C):** The decade divider is used to scale down the frequency for easier counting. While it needs to function correctly, its accuracy is not as critical as the time base because it simply divides the frequency by a known factor.
   - **Temperature coefficient of the logic (D):** This refers to how the logic circuits' performance changes with temperature. While it can affect the operation of the counter, it is not as significant as the time base accuracy in determining the overall frequency measurement accuracy.

3. **Useful Formula:**
   - The frequency measured by a counter is given by:
     $$ f_{\text{measured}} = \frac{N}{T} $$
     where:
     - $N$ = number of cycles counted
     - $T$ = time interval determined by the time base

   - Any error in the time base $T$ directly translates to an error in the measured frequency $f_{\text{measured}}$. Thus, ensuring the time base is accurate is crucial for precise frequency measurements.