Interferences from ‘hostile’ radio communications may harm your system and are difficult to identify. Understand how to able to scan your environment.

Graph showing potential interferences by RF fields in the 860-960MHz frequency band

Graph showing potential interferences by RF fields in the 860-960MHz frequency band

Wireless communications and, in particular, wireless sensor networks enjoy lots of advantages when compared to wired systems. However, they also pose some disadvantages, such as a limited security – depending on the protocols used – or reduced liability in the communication.

Oh, Jesus! What’s the problem now?

You have experienced yourself those uncertainty moments where you are unable to receive reliable data from your wireless system. In fact you have been working with the system in what looked a perfect performance but for some reason you can’t get it to work properly that day.

The odds are high that you modified the system somehow – even if you didn’t notice – to act that way so you will have to go through a hard time spotting what your mistake was. We have all been there, especially if you work in SW development.

‘Hostile’ electromagnetic fields – interferences

However, there may be another issue which is difficult to identify without the proper tools: RF fields creating interferences in your environment. All wireless communications are sensitive to other RF fields. When these RF fields are in the same frequency and bandwidth, interferences occur.

In simple (and not technically accurate) words, when the power level of the signal of your system is similar or lower than the other RF field in your environment, your system will not be able to communicate properly as the ‘noise’ created by the ‘hostile’ field is stronger than the communication created by your system.

In fact, this is how frequency jammers work. They basically transmit high levels of signals in the desired frequency band, thus impeding any wireless system in the area to communicate in that frequency band. These are generally used by military and security bodies to prevent wireless systems from activating potentially harmful devices (i.e. activating a bomb with a cell phone signal).

Unmasking the enemy

You never know who may be working with wireless networks around you – or your system – but they may be interfering with your system! Quality tools such as an spectrum analyzer will scan the environment and tell you which signals are present, at which frequencies and with which power levels. They can be pretty expensive but may be worth having one if you work in this field – starting from $1,000 for the 1GHz frequency band example.

You may also be interested in simpler devices to tell you whether there’s a field that could be affecting your system. In the 860MHz to 960MHz, we have developed a product that lights up an LED whenever there’s a strong RF field in the environment.

Photon detects RF fields that could generate interferences

Photon detects RF fields that could generate interferences

The Photon is a battery-free solution that uses energy harvesting in this frequency to light up an LED. This way we know when a ‘hostile’ RF field is present just by bringing the Photon close to the desired spot.

Again, interferences of RF fields are hard to detect so follow this recommendation: never discard the possibility of a nearby wireless system when ‘random’ things start going on. If you have the proper tools it takes no time and can save you lots of headaches over time.