1.   A radio signal has both electrical and magnetic properties.

2.   Of course, the in-coming signal does not have to be live television.

3.   But officials have long said that the analog radio had problems operating in high-rise buildings, where their signals have difficulty penetrating many floors of steel and concrete.

4.   Obviously, the signal still has a way to go.

5.   Tall people impede the signal more because the signal has farther to travel.

6.   The signal has no trouble passing through non-conducting materials like wood and glass.

7.   These digital camcorders record onto one-hour, matchbox-size tapes called mini-DV cassettes whose signals have high quality that can last forever.

8.   While some current mobile devices can communicate through infrared signals, those signals must have a clear, straight path from one device to the other.

9.   The relative steadiness of the market Tuesday could signal that stocks have more or less reached bottom, analysts said.