wireless sensor basics

This page covers wireless sensor basics and mention wireless sensor types. It include NFC, RFID, bluetooth and zigbee based wireless sensors.

Wireless sensors will have two parts viz. transmitter and receiver. The transmitter part converts signals from process control instruments into wireless radio transmission. The receiver part converts wireless signal into specific desired output(such as analog current or data) .

Day by day Wireless standards are evolving and hence wireless sensors are available for these various standards. Common wireless sensors include NFC sensor, RFID sensor, bluetooth sensor and zigbee based sensor.

wireless Sensor types

NFC sensor: It is a short range wireless communication device where in antenna size is smaller than operating wavelength. It operates either on E field or H field and do not support EM waves.

In mobile phones, NFC used is based on E-field and operates on 13.56 MHz frequency at wavelength of 22.11 meter. This NFC sensor based devices are used at ticket counters as well as for car parking. Refer NFC basics for more.

RFID sensor: This consists of small antenna with small chip. This technology is used to track the items at a distance. It is used for low byte data transfer. The system composed of tags attached to the items and readers. The readers transmit RF waves and receive the reflected waves to determine the distance as well as other parameters.

It is used as barcode or magnetic strip on back of the credit card or debit ATM card. It is basically a unique identifier.
Refer RFID tutorial for more.

Bluetooth sensor: These wireless sensors use UHF band in ISM frequency band. It is used to exchange data over shorter distances. There are various classes of bluetooth devices based on distances and power ranges.
Refer bluetooth versions and bluetooth tutorial for more.

Zigbee sensor: These wireless sensors are based on zigbee standard(IEEE 802.15.4). These high level of communication protocols are used to create PANs. These are low power devices. It covers distance coverage from 10-100 meters in LOS.
Zigbee routing protocols are developed to take care of long distance transmission with the help of mesh network topology. The zigbee network is composed of end devices, routers and co-ordinator.
Refer Zigbee tutorial for more.

Sensors and Transducers Related Links

Proximity Sensor
Occupancy Sensor vs Motion Sensor
LVDT and RVDT sensor
Position, displacement and level sensor
force sensor and strain sensor
temperature sensor
pressure sensor

Also refer IoT compliant sensors which includes ambient light sensor, optical sensor, gesture sensor, proximity sensor, touch sensor, fingerprint sensor etc.

Refer Sensors and transducers article which covers types, basic functions and provide links to sensors and transducers. It include temperature sensor, humidity sensor, strain sensor, proximity or occupancy sensor, force or load sensor, voltage and current sensor, pressure sensor, speed sensor, resistance sensor, power sensor, level sensor, event or state sensor etc.

RF and Wireless Terminologies