Band-stop filter
to reduce or prevent audio feedback, while having little noticeable effect on the rest of the frequency spectrum (electronic or software filters).
However, in the audio band, a notch filter has high and low frequencies that may be only semitones apart.
The difference in the starting and ending frequency points causes the two filters to connect effectively without any overlapping.
A more general approach is to design as a low-pass prototype filter which can then be transformed into a bandstop.
This would be used to filter out the mains hum from the 60 Hz power line, though its higher harmonics could still be present.
When measuring the non-linearities of power amplifiers, a very narrow notch filter can be very useful to avoid the carrier frequency.
Use of the filter may ensure that the maximum input power of a spectrum analyser used to detect spurious content will not be exceeded.
A notch filter, usually a simple LC circuit, is used to remove a specific interfering frequency.
This is a technique used with radio receivers that are so close to a transmitter that it swamps all other signals.
The wave trap is used to remove or greatly reduce the signal from the nearby transmitter.
[3] Most affordable software-defined radios (SDR) on the market today suffer from limited dynamic and operating ranges.
In other words, in real-world operating environments, a SDR can easily be saturated by a strong signal.
FM notch filters are very useful for SDR applications and have increased in their popularity.
In the case of transmission gratings and prisms, polychromatic light that passes through the object will be redirected according to wavelength.
Filters of this design may be high-pass, band-pass, or low-pass, depending on system configuration.
Smoothing filter is essential in many fields, such as signal and image processing, computer vision, statistics, stated by Roonizi (2021).
[5] Algorithms such as quadratic variation regularization and smoothness priors are the most common way to perform signal denoising.
These algorithms are implemented to band-stop smoothing filters and being investigated by Roonizi (2021).
Moreover, it was suggested that positive noise correlation promises to obtain the best band-stop smoothing filter.
The development of telecommunications applications raises the demand of radio frequency and microwave filters, stated by Haddi (2019).
Microwave filters have high flexibility of actualization and low cost.
The band-stop filter in the telecommunications field, has a respectable place which it is essential for microwave transceivers.
For example, wireless communication systems make use of band-stop filters to achieve the requirement of miniaturization.
Microstrip-line band-stop filter is convenient to implement with low cost and light weight.
Hsieh & Wang (2005) stated that, conventional microstrip band-stop filters are made of shunt open-circuited resonators.
The advantages of the microstrip band-stop filter designed by Hsieh & Wang (2005) is its compact size and easy implementation.
This improved band-stop filter with wide stop-band has additional amount of transmission zeros.
As a result, a simple structured band-stop filter with easy implementation can bring advantages of lower-order resonators, great stop band performance when compared to conventional microstrip band-stop filters.
