Caffeine Information. Caffeine is naturally found in cocoa beans, coffee beans and tea and is synthetically produced for use in certain medications and in beverages. This substance is a stimulant drug that quickly enters the bloodstream and affects the brain.
Frequency Range Chart. The radio spectrum refers to the section of the electromagnetic spectrum that holds all possible radio frequencies ranging from 3 kHz to 300 GHz.Radio frequency is used for radio communication technology, wireless networks and telecommunication systems.he radio spectrum refers to the section of the electromagnetic spectrum that holds all possible radio frequencies ranging from 3 kHz to 300 GHz. Radio frequency is used for radio communication technology, wireless networks and telecommunication systems.
What is frequency band? Frequency bands are groupings of radio frequencies that are used by mobile networks to communicate with mobile phones. The frequency bands that a phone supports determine to a large degree where and on which networks it can be used. For example, T-Mobile USA uses the 1900MHz band for its GSM network, while AT&T uses both 1900MHz and the newer 850MHz frequency bands. Europe and most of the rest of the world use the 900MHz and 1800MHz frequency bands for GSM. So for a device to work properly on T-Mobile USA as well as work in Europe, it would need to support the 1900MHz band and one or both of the 900MHz and 1800MHz bands used in Europe.