Test and Measurement World Terminology Section

One Stop For Your Test and Measurement Need

What is ENR | Excess Noise Ratio definition | Y-factor to ENR

This page describes ENR (Excess Noise Ratio) definition. It mentions formula to convert Y-factor to ENR (Excess Noise Ratio). This guide will help in Excess Noise Ratio measurements from ENR and Y-factor equations.

Excess Noise Ratio definition

• It is parameter used in the measurement of noise performance of RF amplifier.
• It is mostly used in the connection with noise diodes.
• Noise level at input of receiver is expressed as follows.
➤ Pn = K*T*B
Where,
K = Boltzmann constant = 1.38 x 10-23
T = Temperature in oK
B = Bandwidth (Hz)
• Receivers with less bandwidth will have high sensitivity.

First stage in a receiver dominates overall noise of it. Overall noise can be reduced when first stage is kept at cold or low temperature. Noise diode device has defined ENR (Excess Noise Ratio).
➤Diode is in OFF state: Noise will be thermal noise as calculated using above formula where as bandwidth (B) is the receiver bandwidth.
➤Diode is in ON state: Noise increases from the thermal noise figure by an amount known as "ENR (Excess Noise Ratio)". The ENR value here can be 6 dB or 16 dB depending upon amplifier gain high or less respectively.

Y-factor to ENR (Excess Noise Ratio) conversion formula

Y-Factor vs ENR (Excess Noise Ratio)... Equation-1

• The formula or equation-1 above mentions relationship between Y-factor and ENR with respect to NF (Noise Figure). If Noise figure or gain of amplifier is known, Y-factor can be converted to obtain ENR value.

• ENR = {( TsON - TsOFF )/To } ... Numeral form
• ENR (dB) = 10* Log10 { ( TsON - TsOFF )/To } ... decibel form
Where,
TsON = Noise temperature when noise source is in ON state
TsOFF = Noise temperature when noise source is in OFF state
To = Reference temperature, 290 oK

Y-factor is expressed as ratio of two noise power levels as follows.
Y = NON/NOFF
Where,
NON = Noise power level when noise source is ON.
NOFF = Noise power level when noise source is OFF.

➤Y = TON/T OFF, (As noise power is proportional to noise temperature)

• Once we have determined Y-factor and ENR using above formula, NF can be easily calculated or measured using equation-1.



Links to useful Measurements

Following are the links to other useful measurements available on Test and Measurement World website.
Difference between EVM vs subcarriers and EVM vs symbols
Current measurement vs Voltage measurement
Inductance measurement vs Capacitance measurement
Difference between Power and Energy measurements
EMC measurement vs EMI measurement
Electric and Magnetic Field Measurements

What is difference between or comparison between

Following links mention difference or comparison between various equipments and terms:
comparison between SPI and I2C
difference between PXI and PCI
Microscope vs Telescope
Amplitude Modulation vs Angle Modulation
difference between modem and router
Air Fuel Ratio Sensor vs O2 Sensor
Radiometer vs Spectrometer vs Spectroradiometer
Clamp meter vs digital multimeter
Colorimeter vs Spectrophotometer
difference between Prism and Grating
difference between Venturi meter and Orifice meter
difference between Lux and Lumens




Share this page

Translate this page

Latest Posts