The signal to noise ratio is also referred to as SNR. Simply put, it is the ratio between the maximum signal strength that a wireless connection can achieve and the noise present in the connection. Here “noise” refers to the stray frequencies that interfere with the transmission of data in a wireless network.
The SNR of a network needs to be as high as possible. The higher the value of SNR, the better will be the signal strength and the quality of transmission. This value can decrease due to various reasons. At the time of rain or fog, the air is denser than usual, so the signals may get attenuated (i.e., get reduced in strength). In these cases the value of SNR will be lowered to some extent. Also, the presence of any strong electrical field in the path of signal, like high tension electrical wiring, can reduce the value of SNR substantially. Too much electronic equipment placed in close proximity of the equipments for wireless network can also interfere with signal strength to quite an extent. The frequencies emitted by other electronic gadgets can often interfere with wireless transmissions, causing a sharp drop in signal strength. Even high powered cell phone handsets have been suspected as possible causes for loss in strength of wireless signals.
If your wireless connection continually suffers from slow data transfer speed, pay close attention to your equipment and look for possible sources of signal disturbance nearby. Some international brands market equipments for wireless networking that naturally resist disturbances in the network. Purchase these equipments whenever possible. Additionally, look out for the following: