Noise Figure

This section is for performing most functions regarding Noise Figure. Noise Figure is a figure of merit of Signal to Noise and the performance of devices and their effect on this signal to Noise ratio or the total noise power.

Noise Conv

This screen is used for converting Noise and Noise Power Units and Noise Measure. For the left side enter the Device Noise Figure in dBF and the Device Gain in dB and press the “Calculate” button to figure the Noise Measure. For the right side enter any one Noise value in Noise Figure in dB, Noise Temperature in Kelvin or Noise Factor and it will  figure the remaining two conversions. I defaulted the Ambient Temperature to 290K or 27C for ease. This temperature is used to figure the temperature of the noise source. Press Calculate to compute and display. Clear to reset and reenter value to retry and Close to Quit.

Figure 103 – Noise Figure Conversions and Noise Measure

Noise Source

This screen is used figuring the Noise Power of a source. For the left side enter the Temperature in Kelvin, the Bandwidth in Hz, the Impedance in Ohms, Device Noise Figure in dBF and the Device Gain in dB and press the “Calculate” button to figure the Noise Power in dBm and Watts and also in Vrms. I defaulted the Ambient Temperature to 290K or 27C and the Bandwidth to 1Hz and the Impedance to 50 Ohms for ease, but the user can change if desired. Press Calculate to compute and display. Clear to reset and reenter value to retry and Close to Quit.

Figure 104 – Noise Figure Noise Source

 

SPA - DANL/NF

This function set calculates the Noise Figure in dBF, the DANL/ANL Displayed Average Noise level or Average Noise Level and the Tangential Sensitivity. Enter the Temperature in Kelvin, the bandwidth in Hertz and one of the three DANL, Noise Figure or Tangential Sensitivity. It will compute the missing factor. If the DANL/ANL check box is checked it computes to/from DANL and unchecked it computes to/from ANL. In the case below I entered the temperature, bandwidth and checked the DANL box and entered the DANL of –88dBm/Hz. It calculated the Noise figure and Tangential Sensitivity of the receiver. Press Calculate to compute and display. Clear to reset and reenter value to retry and Close to Quit.

 

Figure 105 – Noise Figure DANL/ANL to NF and TSS

 

Input Noise Power

This screen is used figuring the Input Noise Power to a Noise Figure Meter or other receiver like a Spectrum Analyzer for instance. It can also be used to back calculate the noise figure of a device given the temperature, gain and Noise Power at Resolution Bandwidth (Bw>1Hz) or Spectral Noise Density or Noise Marker value (Bw=1Hz). This calculation is useful for performing “Cold Power” noise figure measurement vs a Hot/Cold Noise Figure measurement such as with a Noise Figure Meter or the Spectrum Y Factor method. If using the cold power method be sure to clear the value in the DUT NF test box, so it detects the missing value to calculate and add the Input Noise Power value. It senses the missing value and calculates it.

 

Enter the Temperature in Kelvin, the Bandwidth in Hz, the ENR Excess noise Ratio in dB, Pre-Amp Gain in dB, Device Noise Figure in dBF and the Device Gain in dB and press the “Calculate” button to figure the Total Noise Power in dBm/Hz. I default the Ambient Temperature to 290K or 27C and the Bandwidth to 1Hz for ease, but the user can change if desired. Press “Clear” to clear and start over and “Close” to quit the screen.

This screen can also be used to back calculate the device Noise Figure for “Cold Power” measurements. That is the Output Noise Power of a device is dependent on the device gain and Noise Figure. If the Gain is known (measured) you can then back calculate the Noise Figure from the Output Noise Power.

 

Figure 106 – Noise Figure input Noise Power

 

Y Factor

This screen is used for figuring the Noise Figure and Gain of a device using the Y-Factor method. Measure the Noise On and Noise Off power ratio to figure the Noise Figure Using a Spectrum Analyzer, Power Meter or other receiver. Enter the Temperature in Kelvin, the Bandwidth in Hz, Excess Noise Ratio (ENR) of the Noise Source in dB, Input Loss in dB, Noise Power On and Off in dBm and press the Calculate button to figure the Noise Figure Power in dBF and Gain in dB. I default the Ambient Temperature to 290K or 27C and the Bandwidth to 1Hz for ease, but the user can change if desired. Clear to reset and reenter value to retry and Close to Quit.

Figure 107 – Noise Figure Y Factor

 


De/Embed Noise

This screen is used for figuring the Cascaded or Embedded or DeEmbeded Noise Figure of a system. Enter the Input Loss before DUT in dB, the First Stage Gain and Noise Figure and the Second Stage Noise Figure and press the Calculate button to figure the F21 Noise Figure in dBF. In addition you can work the equation backwards to figure what F1 would be needed to get a specific F21 and F2 for the system. I default the Ambient Temperature to 290K or 27C for ease, but the user can change if desired. Clear to reset and reenter value to retry and Close to Quit.

Figure 108 – Noise Figure DeEmbedded/Embedded Noise

ENR Offset

This screen is used for figuring the Excess Noise Ratio (ENR) correction for non-standard ambient temperature and input loss. Enter the Temperature in Kelvin, ENR Excess Noise Ratio of the Noise Source in dB, Input Loss in dB and press the Calculate button to figure the Corrected ENR in dB. I default the Ambient Temperature to 290K or 27C for ease, but the user can change if desired. Clear to reset and reenter value to retry and Close to Quit.

 

Figure 109 – Noise Figure ENR Offset for Loss and Temperature

Noise Error

 

Gain Uncertainty

Enter the System Total Noise Figure (Device 1 and 2), DUT Gain, DUT Gain Uncertainty and the Noise Figure Meter Noise Figure. Press Calculate to perform the calculation and get the Upper and Lower Limit of the DUT (Device 1) Noise Figure measurement. Clear to reset and reenter value to retry and Close to Quit.

 

Figure 141 – Noise Figure Error Gain Uncertainty

 

ENR Error

Enter the Noise Source ENR, the Input Loss, the temperature of the lossy component and the uncertainty of reading that temperature. Press Calculate to perform the calculation and get the Upper and Lower Limit of the Excess Noise Ratio ENR. Press Clear to clear all variables and redo and Close to quit the screen.

 

Figure 142 – Noise Figure Error ENR Error

 

System Noise Error

Enter the Noise Source S11 or Input Return Loss, the DUT Noise Figure, DUT Gain, DUT S11 Input and S22 Output Return Losses. I have some initial estimates of the Known Uncertainties defaulted for the operators help. These particular values are the ones I found for the Agilent instruments. Press Calculate to perform the calculation and get the Calculated Uncertainties: System Total Noise Figure NF12, Noise Figure Meter NF2, DUT Gain and finally DUT Noise Figure. Press Clear to clear all variables and redo and Close to quit the screen.

 

Figure 143 Noise Figure Error System Noise Error

 

Available Gain/Loss

This section computes the available gain for the loss correction factor for input noise test systems from the source, load and input network S-Parameters. Enter the values as shown in Figure 137 and Press Calculate to compute, Close to quit and Clear to clear the value to retry.

 

Figure 144 – NF Available Gain/Loss