Cisco Headend System Release 2.5 Guida Utente
1-44
DHCT Status Reporting Utility
78-738186-01 Rev B
DHCT Transmit Level Saturation Report,
Continued
Case 2
In this example, a quick examination of the graph may lead the system operator to
In this example, a quick examination of the graph may lead the system operator to
believe that the system is healthy. The graph depicts a bell curve with the peak of the
bell curve centered around 40 dBmV, the midpoint between Cisco’s recommended
transmission level of 25 and 55 dBmV.
DHCT Transmit Level Saturation Report - QPSKMOD1
Current Tuner Input Attenuation Level: 2 (-5 to 11
dBmV
)
|-------------------------------------------------------------------------
| T T
| T|T |
| T||| |T T
| T |||| || |T
| | ||||T|| || T
| T T| |||||||T|| |
| T T| ||T||||||||||T|T
| T T| ||T||||||||||||||||TT T
| T TT TT TTTT|T||T|||||||||||||||||||||TT|TTTT
|---------+T--T---T+-T--+----+---------+--------+----+----+--------+--------
|
10 20 25 30 40 50 55 60 70
=================>|<==>|<==========================>|<==>|<=================
^ ^
| |
Settop Signal Core Population Settop Signal
| T T
| T|T |
| T||| |T T
| T |||| || |T
| | ||||T|| || T
| T T| |||||||T|| |
| T T| ||T||||||||||T|T
| T T| ||T||||||||||||||||TT T
| T TT TT TTTT|T||T|||||||||||||||||||||TT|TTTT
|---------+T--T---T+-T--+----+---------+--------+----+----+--------+--------
|
10 20 25 30 40 50 55 60 70
=================>|<==>|<==========================>|<==>|<=================
^ ^
| |
Settop Signal Core Population Settop Signal
Too Weak (25-55
dBmV
) Too Strong
An examination of the chart, however, shows one demodulator (DMod 2) supports
DHCTs that transmit at an average of 25.47 dBmV. Another demodulator (DMod 7)
supports DHCTs that transmit at an average of 50.42 dBmV. Demodulators assigned
to a specific modulator should be configured to expect approximately the same
transmit level from DHCTs. Therefore, system operators should investigate whether
adjustments to the combining or padding networks of these demodulators are
necessary.
Transmit Level Breakdown
QPSK Mod Name ID Avg. Md 20db 25db 30db 50db 55db 60db
----------- --- ----- -- <-----+------+------+------+------+------+-------->
QPSKMOD1 8 41.99 42 9| 43| 219| 5865| 490| 225| 0
DMod: 1 40.98 41 2| 5| 26| 755| 46| 18| 0
DMod: 2 25.47 40 0| 0| 8| 633| 84| 42| 0
DMod: 3 39.42 40 7| 23| 64| 713| 36| 16| 0
DMod: 4 40.56 41 0| 9| 46| 718| 35| 20| 0
DMod: 5 43.51 44 0| 2| 14| 828| 94| 34| 0
DMod: 6 41.96 42 0| 3| 38| 1029| 84| 45| 0
DMod: 7 50.42 47 0| 1| 15| 853| 74| 37| 0
DMod: 8 43.33 44 0| 0| 8| 336| 37| 13| 0
<-----+------+------+------+------+------+-------->