LeCroy 6000 SERIES Operator's Manual page 354

Operator's Manual
Raised Root Cosine (a low-pass filter) Band 1: Pass Band — DC to corner frequency minus
Gaussian
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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:
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)
ISSUED: October 2003 WR6K-OM-E Rev A