SAR, NFC and GPS…interesting

There are uncountable terms about smartphones that we have heard but we don’t really know what they are. In this article let’s get to know about some of the most talked terms when one talks about smartphone utility tech. These are SAR (Specific Absorption Rate), NFC(Near Field Communication) and GPS(Global Positioning System).

Lets begin:

  • Specific Absorption Rate (SAR):

SAR is a measure of the rate of energy absorption by the Human body tissues when exposed to Radio Frequency Waves of the electromagnetic spectrum. Each GSM handset has a radio transmitter and receiver in order to operate in the wireless GSM network. That transceiver is manufactured so that when used next to the ear or when kept in belt pocket, it won’t exceed the limits for exposure to radio frequency energy set by the authorities.

The authorities maintaining SAR protocols are the Federal Communications Commission (FCC) of the U.S. Government, Industry Canada of the Canadian Government (IC), and the Council of the European Union.

The SAR limit set by various authorities are:

  • 1.6 W/kg by FCC/IC (averaged over 1gm of actual tissue)
  • 2.0 W/kg by Council of the European Union (averaged over 10gm of actual tissue)
SAR value information
Source: Gadgets to use
  • Near Field Communication(NFC):

NFC is a short-range high frequency wireless communication technology that enables the exchange of data between devices over about a 10 cm distance.

NFC is an upgrade of the existing proximity card standard (RFID) that combines the interface of a smartcard and a reader into a single device. It allows users to seamlessly share content between digital devices, pay bills wirelessly or even use their cellphone as an electronic traveling ticket on existing contactless infrastructure already in use for public transportation.

The significant advantage of NFC over Bluetooth is the shorter set-up time. Instead of performing manual configurations to identify Bluetooth devices, the connection between two NFC devices is established at once (under a 1/10 second).

Due to its shorter range, NFC provides a higher degree of security than Bluetooth and makes NFC suitable for crowded areas where correlating a signal with its transmitting physical device (and by extension, its user) might otherwise prove impossible.

NFC can also work when one of the devices is not powered by a battery (e.g. on a phone that may be turned off, a contactless smart credit card, etc.).

NFC photo
Photo by osde8info
  • Global Positioning System(GPS):

Global Positioning System was developed by the United States’ Department of Defense and is the most commonly used navigation system.

Some countries have their own location systems which are:

  1. Russia’s GLONASS (Global Navigation Satelite System),
  2. China’s BeiDou (BeiDou Navigation Satellite System),
  3. European Union’s Galileo,
  4. India’s IRNSS(Indian Regional Naviagtion Satellite System).

It uses between 24 and 32 Medium Earth Orbit satellites that transmit precise microwave signals. This enables GPS receivers to determine their current location, time and velocity. The GPS satellites are maintained by the United States Air Force.

GPS is often used by civilians as a navigation system. On the ground, any GPS receiver contains a computer that “triangulates” its own position by getting bearings from at least three satellites. The result is provided in the form of a geographic position – longitude and latitude – to, for most receivers, within an accuracy of 10 to 100 meters. Software applications can then use those coordinates to provide driving or walking instructions.

Getting a lock on by the GPS receivers on the ground usually takes some time especially where the receiver is in a moving vehicle or in dense urban areas. The initial time needed for a GPS lock is usually dependent on how the GPS receiver starts.

The GPS receiver has to attempt to lock onto a satellite signal from any available satellites, basically like polling, which takes a lot longer than knowing which satellites to look for. This GPS lock takes the longest.

In an attempt to improve lock times, cellphone manufacturers and operators have introduced the Assisted GPS technology, which downloads the current ephemeris for a few days ahead via the wireless networks and helps triangulate the general user’s position with the cell towers thus allowing the GPS receiver to get a faster lock at the expense of several (kilo)bytes.


I hope that now you have better understanding of the terms mentioned above. Now go and flaunt your knowledge.


Thanks a lot for coming and happy reading :-).