The Definition and Meaning of Wireless Internet Signal in Decibels
A decibel is a measure of relative power. In order to measure absolute power, a dBm is defined as the ratio of the measured power relative to one milliwatt. WiFi power levels are measured in dBm.
Other People Are Reading
-
Base 10 Logarithm
-
A decibel, or dB, is defined as 10 times the base 10 logarithm of a power ratio. The logarithm base 10 means "What number could I use as an exponent of 10 to get the number in question?"
The Meaning of dB Levels
-
Numbers are useful only if you know what they mean. A dB of 0 means that the two power levels are equal. A dB level of -20 means the power is 100 times smaller. With WiFi networks, adding up the losses gives the total loss. For example, a plaster wall can cause a 3dB signal loss. A distance of 100 meters can cause an 80 dB loss. A WiFi terminal 100 meters away from an access point and on the other side of a plaster wall will have an 83 dB loss.
-
Power Measurement With dBm
-
Power levels are limited for WiFi transmitters. Absolute power is measured by relating it to milliwatt, expressed as dBm. A dBm level of 0 means the measured power is 1 milliwatt. WiFi power levels are limited to 30 dBm, or 1 watt transmit power.
-
References
Resources
- Photo Credit decibel scale image by Vladislav Gajic from Fotolia.com numbers on sign image by Evan Meyer from Fotolia.com the power image by Rich Johnson from Fotolia.com
