Wireless communication is becoming an important part of our everyday life. Design engineers need to be mindful of have multiple design parameters when designing products for wireless applications. One of the parameters that need careful evaluation is the frequency band to be used for the wireless application.
In the world of ultra low power wireless devices compliant to the IEEE 802.15.4 standard, the number of bands to choose from are relatively low – it’s basically a choice between the 2.4GHz ISM band available worldwide, or the regional Sub1Ghz frequency bands at 700/800/900MHz.
Looking at the characterstics of the Sub1GHz vs 2.4GHz designs, ahcieving maximum range, yet keeping the power consumption to the ultimate minimum – it’s pretty much all about the physics.
At lower frequencies it takes less power to achieve the same range as higher frequencies. Free space path loss (FSPL) is given by the formula:
FSPL (dB) = 20 log10 (d) + 20 log10 (f) + 32.44
d is the distance of the receiver from the transmitter (km)
f is the signal frequency (MHz)
The result shown in the table below comparing two IEEE 802.15.4 compliant transceivers, operated at the same conditions, one at 2.4GHz and one at 915MHz shows a range benefit of ~2.6x for the Sub1GHz system.
In addition to the superior range given by the law of physics, Sub1Ghz also penetrate concrete, walls and humid environment much more effieciently. In some regions you will also experience a less crowded environment, not subject to interference from Wi-Fi, Bluetooth, and other consumer devices operating in the 2.4GHz frequency band.
Atmels® AT86RF212B Ultra Low power Sub1GHz RF transceiver has been designed for wireless products compliant to the IEEE 802.15.4 standard. It is a direct sequence spread spectrum RF transceiver, supporting various datarates from 20kb/s to 1000kb/s. Power consumption is as low as 0.2uA in sleep, 9.2mA and 18mA in receive and transmit, respectively. Maximum RF output power is +10dBm, while the receiver is able to receive signals down to -110dBm.
The AT86RF212B is designed to meet the tough requirements of systems in harsh environments, demanding years of maintenance free operation from a single battery cell. Example uses such as gas- and water-meters, ligthing control, environemental monitoring and other proprietary systems up to 1000kb/s.
If you are interested in experiencing the benefits of this ultra low power Sub1GHz RF transceiver, please visit store.atmel.com to purchase your AT86RF212B Evaluation Kit today. We’ll follow up with tips/tricks on how to evaluate the AT86RF212B using the Wireless Composer in Atmel Studio 6. Stay tuned!!!