Operation Manual Part 1

Digital Liquid Cooled UHF
TV Equipment
Detailed operational description
9946 V1
45321648.01 104 A E
preliminary
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Numéro / Number Doc. Rev. Lan
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16/06/2006
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Information contained is this document is confidential, is THOMSON property and cannot be disclosed in whatever form without prior written authorization of THOMSON.
In a transmitter configuration containing several cabinets, each cabinet has its own protection system
controlled by the multiplex card. The two loop protection systems are connected together so that open
circuiting the first either one will cause the shutdown of the cabinet. The protection systems are
identical on both cards with the exception of the station protection.
In the case of a 3.75 or 5 kW transmitter in which the second multiplex card is in the same cabinet, the
loop protection system on the second card does not accept the surveillance signals; it is simulated by
a hardwired closed loop.
2.3.6. Computing the overall quality assessment of the RF signal
The quality of the RF output signal of a digital transmitter is assessed by a number between 1 and 20,
called overall quality assessment (QN).
This overall quality assessment is indicated in a window of the PCL and also on the remote control
position.
This assessment is processed by the transmitter CPU and a "fault" signal is sent on a hard wired
connection. This fault loop, along with the overall quality assessment, is used in PR or N+1 transmitter
systems for automatic transmitter changeover.
For a transmitter, the overall quality assessment (QN) is obtained by computing the cubic root of the
quality assessments for the following parameters:
♦ Shoulder level of the RF signal,
♦ Ripple level of the RF signal,
♦ RF output power of the transmitter.
For a given parameter, the quality assessment is computed from:
♦ The Correction threshold of the parameter (C
S: Correction threshold for Shoulder, CR: Correction threshold for
Ripple,
PN: Nominal Power), beyond which the MODAP performs a correction,
♦ The actual parameter value (as measured),
♦ The Quality threshold of the parameter (S:
quality threshold for Shoulder, R: quality threshold for Ripple, P:
quality threshold for Power), beyond which the transmitted signal quality is considered to be bad. When
this threshold is exceeded for a parameter, the quality assessment for that parameter equals «5».
The quality assessments for the parameters are computed as follows:
♦ Quality assessment for Shoulder : N
S = 20 – ((Measured value of parameter – CS )* 15 / S)
♦ Quality assessment for Ripple : N
R = 20 – ((Measured value of parameter – CR )* 15 / R)
♦ Quality assessment for Power : N
P = 20 – ((Measured value of parameter – PN )* 15 / P)
These equations provide the following
results:
♦ A quality assessment of 5 when the
difference between the Measured
value and the Correction threshold of
the parameter equals the Quality
threshold of the parameter.
♦ A quality assessment of 20 when the
Measured value of the parameter is
higher than or equal to the Correction
threshold.
Measured value
of parameter
Correcting threshood
of
p
aramete
r
Quality threshold
of parameter
Quality
assessment of
parameter
20
05
When the quality assessment for one parameter is 5 while the other two assessments are 20, the
cubic root is 13. Such overall transmitter quality assessment is considered a major fault.