View source for Eb/N0

The term Eb/N0 ("e bee over en zero") is used in digital communications as a measure of signal strength to estimate the [[BER|bit error rate]].

It is defined as the average energy per bit (Eb) relative to the spectral noise density (N0) and
gives a basic measure how strong the signal is at the receivers input.

The definition assumes that inside the channels bandwidth B the Gaussian distributed noise energy can be calculated
as N0 = k*T*B (may be additionally shaped by filters), where k is Boltzmann's constant and T is absolute temperature in Kelvin.

With the knowlegde of modulation and Eb/N0 one can estimate the available [[BER]] or vice versa calculate the RF power for a given data set of modulation, channel bandwidth, symbol rate, losses and wanted bit error rate. Eb/N0 gives also modulation choices for a channel depending on wether bandwidth (i.e. cable TV) or power (i.e. sat) is the limiting factor. 
 

== Relation to CNR==
C/N = Eb/N0 * fb/B 

fb : bit rate at receiver
B  : channel noise bandwidth

==Relation to SNR==

TODO: add text.

==Estimated BER vs Eb/N0 for a few modulations==

[[File:est_BER_vs_EbN0.png|left|]]

NOTE: Eb/N0 in logarithmic scale here.

[[Category:Technology]]