Adaptive Signal Processing

Adaptive filters, LMS algorithm, RLS algorithm, and applications in noise cancellation, system identification, and channel equalization.

What is an adaptive filter?

"An adaptive filter is a system with a linear filter that has a transfer function controlled by variable parameters and a means to adjust those parameters according to an optimization algorithm."

Why are almost all adaptive filters digital filters?

"Because of the complexity of the optimization algorithms, almost all adaptive filters are digital filters."

Why are adaptive filters required for some applications?

"Adaptive filters are required for some applications because some parameters of the desired processing operation are not known in advance or are changing."

How does a closed loop adaptive filter work?

"The closed loop adaptive filter uses feedback in the form of an error signal to refine its transfer function."

What is involved in the closed loop adaptive process?

"The closed loop adaptive process involves the use of a cost function, which is a criterion for optimum performance, to feed an algorithm, which determines how to modify the filter's transfer function."

What is the most common cost function used in adaptive filters?

"The most common cost function is the mean square of the error signal."

How has the power of digital signal processors affected the use of adaptive filters?

"As the power of digital signal processors has increased, adaptive filters have become much more common and are now routinely used in devices such as mobile phones and other communication devices, camcorders and digital cameras, and medical monitoring equipment."

What are the variable parameters in an adaptive filter?

"An adaptive filter has a linear filter that has a transfer function controlled by variable parameters."

Why are optimization algorithms used in adaptive filters?

"Because of the complexity of the optimization algorithms, almost all adaptive filters are digital filters."

In what kind of space would the locations of reflective surfaces be unknown or changing?

"The locations of reflective surfaces in a reverberant space."

What factor determines how the filter's transfer function is modified?

"An algorithm determines how to modify the filter's transfer function."

What kind of signal is used as feedback for an adaptive filter?

"An error signal is used as feedback for an adaptive filter."

What is the purpose of the cost function in adaptive filters?

"The cost function is a criterion for optimum performance of the filter."

How are adaptive filters used in mobile phones and communication devices?

"Adaptive filters are now routinely used in devices such as mobile phones and other communication devices."

Which type of filters have become more common as digital signal processors became more powerful?

"Adaptive filters have become much more common."

What type of filters are commonly used in camcorders and digital cameras?

"Adaptive filters are routinely used in camcorders and digital cameras."

Where are adaptive filters used in medical applications?

"Adaptive filters are routinely used in medical monitoring equipment."

What is the function of the cost function in adaptive filters?

"The cost function is a criterion for optimum performance of the filter."

Why are variable parameters necessary in adaptive filters?

"The transfer function of an adaptive filter is controlled by variable parameters."

What is the main goal of adaptive filters?

"The main goal of adaptive filters is to minimize the cost on the next iteration."