Cell+Phones

1. Nikolai Tesla in the 1880's 2.CB radios are half-duplex devices so two people talkingon a CB radio use the same frequency, so only one person can talk at a time. A cell phone is a full-duplex device. so you use one frequency for talking and a different frequency for listening. 3.because the are made up of multiple cells 4.FSK uses two frequencies, one for 1s and the other for 0s, switching between the two to send information between the cell tower and the phone. Clever modulation and encoding schemes are required to convert the analog information to digital, compress it and convert it back again while maintaining an acceptable level of voice quality