Teledyne-lecroy DFP2 - Digital Filter Package 2 Instrukcja Użytkownika Pobierz pdf (Strona 10)

8 ISSUED: June 2013 923134 Rev A

Raised Root Cosine (a low-pass filter)

Band 1: Pass Band — DC

to corner frequency minus

half width; signal passes unattenuated.

Band 2: Transition Region — corner minus half width to

corner plus half width; attenuation increases with

frequency with a rolloff shape of 0.5[cos(a) + 0.5]½,

where a ranges from 0 to p over the transition region.

This region is determined by b, which is specified as a

percentage of the corner frequency.

Band 3: Stop Band: — above corner frequency plus

half width; signal is highly attenuated.

The impulse function for the square-root raised cosine

filter is:

Gaussian

Band 1: Pass Band — DC

to half power bandwidth%

times modulation frequency, pass; 3 dB down at half

power bandwidth.

The shape of a Gaussian filter’s frequency response is

a Gaussian distribution centered at DC. The signal

becomes more attenuated with increasing frequency. It

is not possible to specify a transition region or a stop

band for Gaussian filters. However, the BT value, a

fraction of the symbol frequency, determines the filter’s

width, where:

B = half power bandwidth

T = bit (or modulation period)

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Teledyne-lecroy DFP2 - Digital Filter Package 2 Instrukcja Użytkownika Strona 10