R&S SMJ100A, Руководство по эксплуатации, Страница: 353 / 874

Instrument Function
R&S
®
SMJ100A
337 Operating Manual 1403.7458.32 ─ 14
Cut Off Frequency
The cut-off frequency or corner frequency is a filter characteristic that defines the fre-
quency at the 3 dB down point. This frequency is bound to the transition band; here the
filter characteristic changes form the passband to the stopband, where the signal is
suppressed.
Rolloff Factor
The rolloff factor is a measure for the excess bandwidth compared to the ideal band-
width of a "brick like" filter. The roll off factor affects the steepness of the filter flanks. A
"Rolloff Factor" = 0 would result in the steepest theoretically possible flanks ; values
near to 1 make the flanks more flat.
Passband
The passband describes the frequency span that the filter passes unchanged. The
total passband of a filter is given as follows:
Bandwidth = (1 + "Roll Off Factor") * "Symbol Rate"
Cut Off Frequency Shift
The "Cut Off Frequency Shift" affects the cut-off frequency in the way that the filter
flanks are "moved" and the passband increases by "Cut Off Frequency Shift"*"Sample
Rate":
Cut Off Frequency = (1 + "Cut Off Frequency Shift") * "Sample
Rate"
Baseband Signal - Baseband Block