What is a controlled signal?

Related questions

1. Why do trains have signals?
2. What is a shunt signal?
3. What is Warner signal?
4. What do train signal lights mean?
5. What is moving block system?
6. What is fixed block?
7. What is a subsidiary signal?
8. How many types of signals are there in railway?
9. When approaching a railroad crossing with flashing lights you must?
10. What is signal overlap?

Tags

1. #computer
2. #light
3. #wireless
4. #command
5. #electricity
6. #travels
7. #pulse
8. #represents
9. #signal
10. #control
11. #definition
12. #frequency
13. #channel
14. #network