Receiver Thermal Noise
Apply receiver thermal noise to complex signal
Libraries:
Communications Toolbox /
RF Impairments and Components
Description
The Receiver Thermal Noise block applies receiver thermal noise to a complex signal. The block simulates the effects of thermal noise on a complex signal. The Specification method parameter enables specification of the thermal noise based on the noise temperature, noise figure, or noise factor.
Examples
Extended Examples
Ports
Input
Output
Parameters
Block Characteristics
Data Types 

Multidimensional Signals 

VariableSize Signals 

Algorithms
Wireless receiver performance is often expressed as a noise factor or figure. The noise factor is defined as the ratio of the input signaltonoise ratio, S_{i}/N_{i} to the output signaltonoise ratio, S_{o}/N_{o}, such that
$$F=\frac{{S}_{i}/{N}_{i}}{{S}_{o}/{N}_{o}}\text{\hspace{0.17em}}.$$
Given the receiver gain G and receiver noise power N_{ckt}, the noise factor can be expressed as
$$\begin{array}{c}F=\frac{{S}_{i}/{N}_{i}}{G{S}_{i}/\left({N}_{ckt}+G{N}_{i}\right)}\\ =\frac{{N}_{ckt}+G{N}_{i}}{G{N}_{i}}\text{\hspace{0.17em}}.\end{array}$$
The IEEE defines the noise factor assuming that noise temperature at the input is T_{0}, where T_{0} = 290 K. The noise factor is then
$$\begin{array}{c}F=\frac{{N}_{ckt}+G{N}_{i}}{G{N}_{i}}\\ =\frac{GkB{T}_{ckt}+GkB{T}_{0}}{GkB{T}_{0}}\\ =\frac{{T}_{ckt}+{T}_{0}}{{T}_{0}}\text{\hspace{0.17em}}.\end{array}$$
T_{ckt} is the equivalent input noise temperature of the receiver and is expressed as
$${T}_{ckt}={T}_{0}(F1)\text{\hspace{0.17em}}.$$
The overall noise temperature of an antenna and receiver T_{sys} is
$${T}_{sys}={T}_{ant}+{T}_{ckt}\text{\hspace{0.17em}},$$
where T_{ant} is the antenna noise temperature.
The noise figure NF is the dB equivalent of the noise factor and can be expressed as
$$NF=10{\mathrm{log}}_{10}(F)\text{\hspace{0.17em}}.$$
The noise power can be expressed as
$$N=kTB={V}^{2}/R,$$
where V is the noise voltage expressed as
$${V}^{2}=kTBR,$$
and R is the reference load.
Extended Capabilities
Version History
Introduced before R2006a
See Also
Blocks
 I/Q Imbalance  Free Space Path Loss  Memoryless Nonlinearity  Phase Noise  Phase/Frequency Offset