*Question E4E03:
Which of the following types of noise are removed by a noise blanker?*  

*Correct Answer is  B: Impulse noise*  

### AI Response: (may contain errors)  

A noise blanker is a feature in some radio receivers designed to reduce or eliminate certain types of noise that can interfere with signal reception. Let's examine the types of noise mentioned in the question:

1. **Impulse Noise (Correct Answer: B)**:  
   - Impulse noise is characterized by short, sharp bursts of interference. It is often caused by sources like lightning, engine ignitions, or electrical switches.  
   - A noise blanker is specifically designed to detect these short bursts and remove them from the received signal, improving the clarity of the communication.

2. **Broadband White Noise (Choice A)**:  
   - Broadband white noise is a continuous noise that covers a wide range of frequencies. It is more random and persistent than impulse noise.  
   - Noise blankers are not effective against broadband white noise because it lacks the distinct, short-duration characteristics that the blanker is designed to detect and remove.

3. **Hum and Buzz (Choice C)**:  
   - Hum and buzz are typically low-frequency noises often caused by power line interference or ground loops.  
   - These types of noise are continuous and do not have the impulsive nature that a noise blanker can effectively eliminate.

4. **All these choices are correct (Choice D)**:  
   - This choice is incorrect because a noise blanker is specifically effective against impulse noise, not the other types of noise listed.

In summary, a noise blanker is most effective at removing impulse noise due to its ability to detect and suppress short-duration interference, which is not the case for broadband white noise or hum and buzz.