I
-
Test Descriptions
In-Channel Frequency Response Test Description
I
REF
04 58 NOV 23. 1993
CHANNEL 4
tsTD)
MKR 70.875
MHz
GTPOf
LOG
4
dB/
WA St
SC
Ft
CORI
MARKER 1
MARKER 2
MORE
I
CENTER 69.000 MHZ
SPAN 6.000
MHz
XRES
EW 300
kHz
#VBW
3
MHz XSWP
6.90
set
Figure g-17. Multi-Burst Response
Single line
VITS
Testing Single line vits testing can be performed on multiburst, sin X/X, Philips ghost
canceling reference (GCR), or NTC-7 combination.
GCR provides the best results because it has the most signal level and it is a
swept frequency over the range of interest.
The sin X/X is also a continuous signal in the frequency domain when using
100
kHz
resolution bandwidth for detection. Its lower energy content requires
higher signal levels or averaging to be used to get equivalent results to the
GCR.
Multiburst can be used but it does not provide a continuous display across the
channel as does GCR and sin X/X.
The NTC-7 combination signal is the least ideal. It would be useful for
relative measurements. The frequency burst’s lengths are not equal and
too short in duration for the 300
kHz
resolution bandwidth to capture them
accurately. Some modified NTC 7 combination test signals have near equal
pulse widths and are more suitable for this test.
Refer to “In-channel frequency response test” in Chapter 2 for illustrations of
the various test signals.
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