e .
Band-Reject F i l ter
The two channels of the instrument, one in High-Pass and the ather in Law-Pass
mod e , may be connected i n para l l e l , as shown i n F i g . 2-11 to provide B and
Reject o peration . F l at Ampl itude response should be uti l ized i n both channe l s .
The i n put signal should be connected to both i n puts ( I N 1 and I N 2) . The outputs
( OUT 1 and OUT 2) should be summed through 1 K, 1% resistors . The output
signal is ava i l able at the common poi nt of these resistors. This connection produces
a possband i nsertion loss of
6
dB .
CAUTION
Both channe I s must be set to the same gai n setti ng . I f
they are bath set to 0 d B g a i n , the output wi l l b e
6
dB
be low the input l eve l in the passban d . If they are both
set to 20 dB gain , the output w i l l be 1 4 dB above the
i n put level in the possband .
The reje ction band i n this configuration extends from the Low -Pass Cutoff Frequency
to the H igh -Pass Cutoff Frequency. Again , the overa l l response may be determ i ned
by combining the normal ized plots g iven in Figures 2-3 through 2 -6 .
f.
S harp-Notch Fi l ter
(Model 452 on ly)
The Sharp-Notch response shown in Fig . 2 -12 is a special case of Bond -Reject
operation of Model 452 . Input signa l , channel connections, etc . should be
made as described under Band-Re ject fi l te ring .
To obta i n a notch (or nul l ) at a desi red frequency fa , the High-Pass Cutoff Frequency
is set to 1 .75 fa and the Low-Pass Cutoff Frequency is set to 0 . 57 fa . For
optimum re jection the H igh-Pass and Low-Pass settings should be a l ternati ve l y
adjusted , starting with the least signifi cant digits.
CAUTION
While the maximum rejection obtainable i n this mode of
operation approaches the noise floor of the i nstrument, the
maximum measurable re jection may be l imited by the harmonic
content of the input sinewave . In this made of operation , it
is thus possible to use the i nstrument for distortion ana l ysis.
2-9
Summary of Contents for 452
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