Filter Design - Non Recursive Flashcards
Whats the general form of the casual LTI processor:
What are the idealised responses for low pass, high pass, bandpass and band stop
What is the frequency response and transfer function that corresponds to the difference equation relating to the output of a non recurisive filter.
What are non recursive filters equal to - what are the parts to this?
FIR Filter impulse response - Transfer function and frequency response are what this is made up of?
What is H(Ω) to?
The real function of Ω, implying a zero phase filter
DEscribe what a simple moving average filter is? what is the supporting formula that goes along with this filter
Describe how the frequency response magnitude characteristics configurations can be show… and how 21 terms and 51 terms may change the result respectively
How might a simple bandpass filter be derived from a low pass prototyple? - graphic
Summarize how a high or band pass filter may be deived from a low pass filter
multiply (modulate) the origional impulse response by signal cos(nΩ0) where Ω0 = desired center frequency of the new filter
(knowing that time domain convolution = frequency domain multiplication)
this shifts the pass band from Ω = 0 to Ω0 = +- Ω0
What is the moving average impulse response
Describe the basis of the fourier transform method
emphaises on seros and poles
Take the transform equation(X(Ω)) and the inverse function rewritten to describe a LTI Processor rather than a signal (h[n])
Starting with H(Ω) and deriving the impulse response h(n)
Fourier transform method equations
Describe what truncation is
truncation is where you just cut off a signal. The effect is you get sidelobes of a certain size (dB)
Decribe an idea low pass filter (graphic)
DEscribe 3 different frequanecy responses to an ideal linear phase band pass filter . Talk through each one
Describe windowing in both the time domain and the freqency domain
Describe how the dB system is used and which are the important log values that correspond to it.
Describe how side lobes work and the ideal value for them to be in a filter design
ideally below -40dB (0.01)
What is the spectrum given by a rectangular window?
Triangle window spectrum and its technical name
Barlett
Hamming window definition
von Hann window definition
What does the kaiser window give the design the ablility to do?
It gives the designer the ablility to control how much ripple the filter has. As shown in this image
Kaiser window definition
Describe what happens with the Eqiripple filter
This is where the designer can choose exactly what parameters the signal should ripple against
What are the corresponding formulas relating to the the equiripples filter
What are the difference betwen a recursive and non recurisve filter and what are the disadvantages and advantages of each other
Recursive (typically IIR) = feedback - alot less terms and therefore memory required to create filters of the same performance as there corresponding non-recurisve design. They can be integraters
non-recursive are always FIR (filter Impulse Response). they are split into window designs. They are capable of being differentiators..
Recursive filters transfer function difference equation definition and pole zero description.
