Difference between revisions of "Smartphone Wireless"

Revision as of 18:04, 20 December 2020

Full Title or Meme

There are a large number of radios on a Smartphone. This wiki looks at those that are not part of the cellular network.

Context

Terminology

• RF = Radio Frequency
• HF = High Frequency
• UHF = Ultra High Frequency
• IR = Infrared
• Light is even higher, but that is handled by the camera and not radios
• Exciter = an antenna that is designed to send energy to a passive RFID tag

Existing Bands

RFID

RF Identifier

• Passive = no battery, typically a tag applied to a inventory item - read range has been 12-15 originally now 30+ feet
• Battery Assisted Passive = typically a monitored sensor that is polled by RF
• Active = has batter and dual antenna - read range 300 feet
• Low Frequency 120 to 150 kHz.
• HF/NFC 13.56 MHz
• UHF = 300 MHz to 3 GHz
• UHF Gen2 = 860 to 960 MHz (works through rain)

NFC

Near Field Communications

• Apple Pay
• Android Pay
• Smart card with build in antenna
• 13.56 MHz

BLE

Bluetooth low energy + battery powered

• Also excited by a stationary antenna that causes the smartphone to respond
• Needs to have an app on a smartphone that is powered up and has bluetooth enabled that responds to the message with a UUID
• Operations at 2.4 GHz at about 70 meters between device and anttenna.

WiFi

Generally used for local internet connections. Can also be enabled by one of the above to send a UUID.

References