The applet applies the Wiener-Kinchine relations and convolution theory, and offers a variety of band shape examples, to demonstrate the performance of wideband IFM frequency discriminator and phase discriminator subsystems.
In this applet, there are no restrictions on the RF band shape, but the accuracy improves with the number of data points. Also, there are no restrictions on video bandwidth.
The plot at the top of the display area shows the normalized spectra of signal x noise and noise x noise vector in-phase and quadrature video output components.
As well as the total output SNR, vector in-phase and quadrature SNRO is calculated for the selected spot signal frequency.
The lower three plots show the total output SNR and the RF input gain and noise figure data.
Figures to the left of the lower three SNR, gain and noise figure plots, refer to the nominal mean parameter values.
Gain and noise figure may be modified interactively as a function of frequency for the first three examples by aligning the mouse on the subband center black spots and dragging these vertically to new values.
Actual within-band values for RF, subband, gain, and noise figure, referenced to the mouse x-axis position within the RF band are displayed at the top of the display region.
There are five band-shape examples selectable via a drop-down menu.
The final two examples are more realistically defined by Butterworth and Chebyshev filter characteristics. Modifying the RF band and bandwidth controls demonstrates likely band edge performance.
Number of subbands, nominal gain, noise figure, video bandwidth, and diode video TSS are modified by the relevant scrollbar.
SNRO defines the receiver performance and becomes a function of both of input signal power and signal frequency.
The noise spectra are normalized for the display, but the total, vector in-phase, and quadrature SNRs resulting, are listed. These track the signal frequency selected using the scrollbar.
Adjustment of the Line Delay scrollbar affects the spectra detail. A zero value simulates the RF amplifier-detector reciver while its maximum value simulates the interferometer. Intermediate values model the IFM discriminator.

User Notes:
The video TSS is referred to a video bandwidth of 2 MHz which is as usually quoted in manufacturers data. Changing the video bandwidth scrollbar automatically adjusts the diode video noise contribution, and the predicted value for this video band is also displayed.
Modifying the gain and noise figure plots in the examples shows directly the effect of parameter variation on the resulting SxN and NxN output noise.
Data from real systems is evaluated by loading user data based on the load file specification. as a formatting guide.
An example user file RFA.txt may be loaded, edited if necessary, and selected from the Examples drop-down menu.
The output SNR determines the likely parameter measurement uncertainty.
Diode detector noise is modeled although any quadrature multiplier phase errors are ignored