
12. Noise Sidebands Test
11. A correction factor of 2.5
dB
must be added to the value
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
measured in step 9 to compensate for logarithmic amplification
and envelope detection. Add this correction, then subtract 10 log
(BW,,,) to compute the noise sideband level in
dBc
referenced to
a 1 Hz bandwidth:
dBc
+ 2.5
dB
-
10
log(BW
enp)
=
dBcil
Hz
The result should be
<
-80
dBc/l
Hz.
Press (SHIFT) [SWEEP
TIMES.
Change
CFREQUENCY
SPAN) to 2.5
kHz.
Press
[SHIFT)
(VlDEoJ
G.
When the VID AVG readout reaches 10,
press
@iYiF),
TRACE B
@LXiZ].
Press MARKER (PEAK SEARCH), Ln] and key in 1
kHz.
Record the MARKER A amplitude:
dBc.
Compute the noise sideband level at a 1
kHz
offset by the
procedure of steps 10 and 11, but find BW,,, for the 30 Hz
resolution bandwidth filter:
dBc
+ 2.5
dB
-10
log(BW,,,)
=
dBcil
Hz
The result should be
c-85
dBc/l
Hz.
Press
@iF)
[SWEEP
m4tE~.
Change
~FREQUENCY
SPAN) to 25
kHz.
Press (SHIFT) (VIDEO]
G.
When the VID AVG readout reaches 20
or higher, press
cm]
TRACE B
@FiFJ
Press MARKER (PEAK SEARCH], la] and key in 10
kHz.
Record the MARKER A amplitude:
dBc.
Compute the noise sideband level at a 10
kHz
offset by the
procedure of steps 10 and 11, using the 3
dB
bandwidth recorded
in
Table
2-5 for the 300 Hz resolution bandwidth filter:
dBc
+ 2.5
dB
-
10
log(BW,,,)
=
dBc/l
Hz
The result should be
c-90
dBc/l
Hz.
Press
(SiYiFj
(SWEEP.
Change [FREQUENCY SPAN] to 250
kHz.
Press [SHIFT)
I-1
G.
When the VID AVG readout reaches 30
or greater, press
(*I,
TRACE B
(j-j.
Press MARKER (PEAK SEARCH)
Ia]
and key in 100
kHz.
Record the MARKER A amplitude:
dBc.
Compute the noise sideband level at a 100
kHz
offset by the
procedure of steps 10 and 11, using BW,,, for the 3
kHz
filter:
dBc
+ 2.5
dB
-
10 log (BW,,,) =
dBc/l
Hz.
The result should be
c-105
dBc/I
Hz.
2-52 Performance Tests
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