G / T

G / T , short for English gain-to-noise temperature , in English mostly as reception quality denotes the ratio is off gain G and noise temperature T a receiving device . The unit is 1 / K . If the ratio is given in decibels , it is called dB / K; this term is a closed expression, not a quotient of dB and K.

The reception quality summarizes the quality of the reception chain, including the reception antenna and intermediate amplifier .

G / T is proportional to the carrier-to-noise ratio  C / N :

${\displaystyle G/T={\frac {k_{\mathrm {B} }\cdot B\cdot F}{P_{\text{t}}\cdot G_{\text{t}}}}\cdot C/N}$

With

• Boltzmann's constant ${\displaystyle k_{\mathrm {B} }}$
• Bandwidth B
• Free space attenuation F
• Transmission power ${\displaystyle P_{\text{t}}}$
• Antenna gain of the transmitter. ${\displaystyle G_{\text{t}}}$

Example: A receiver has an antenna gain of and a noise temperature Then the ratio is ${\displaystyle G=10\,\mathrm {dB} =1\,\mathrm {B} ={\frac {P_{2}}{P_{1}}}=10}$ ${\displaystyle T=100\,\mathrm {K} .}$

${\displaystyle \Rightarrow {\frac {G}{T}}={\frac {10}{100\,\mathrm {K} }}=0,1{\frac {1}{\mathrm {K} }}=10^{-1}\,{\frac {1}{\mathrm {K} }}=\mathrm {\frac {-1\,B}{K}} =\mathrm {\frac {-10\,dB}{K}} .}$

literature

• Jürgen Detlefsen, Uwe Siart: Basics of high frequency technology . 2nd, expanded edition. Oldenbourg, Munich et al. 2006, ISBN 3-486-57866-9 ( limited preview in the Google book search).