Daily Impact
Every day, users rely on allocation of frequencies for efficient use of such devices as:
- cell phone
- cordless phone
- garage door opener
- car key remote control
- broadcast television and audio
- Standard time broadcast
- vehicle-speed radar, air traffic radar, weather radar
- mobile radio
- Global Positioning System (GPS) navigation
- satellite TV broadcast reception; also backend signal dissemination
- Microwave oven
- Bluetooth
- Wifi
- Zigbee
- RFID devices such as active badges, passports, wireless gasoline token, no-contact credit-cards, and product tags
- toll-road payment vehicle transponders
- Citizen's band radio and Family Radio Service
- Radio control, including Radio-controlled model aircraft and vehicles
- wireless microphones and musical instrument links
Power levels vary widely (from 1 milliwatt in a Bluetooth node to 1 kilowatt in a microwave oven). While the general RF band controls propagation characteristics, who uses what is arbitrary and historical. A particular frequency may require line of sight, or may be attenuated by rain, but whether it carries ambulance or pizza delivery traffic depends on what region it's used in.
Earlier equipment could not process higher frequencies, nor was it compact enough to support certain uses. Over time the exploitable frequencies have increased and semiconductors have shrunk. A tube radio is neither mobile nor reasonably battery powered; GPS works at 1,500 MHz and fits in a pocket. A Bluetooth headset can talk to a mobile phone which is trunked on a microwave link, and at the other end someone is on a cordless phone.
Read more about this topic: Frequency Allocation
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