Operation Manual Part 3

Digital Liquid Cooled UHF
TV Equipment
Operating modes and Control modes
9946 V1
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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.
♦ when the manual on-air mode is selected, switching to air and switching off-air are available as
specific operator commands; when the transmitter has been switched on all power supplies are on
irrespective of the presence or not of video at the input.
4.4. Different operational states of exciter
(Dual drive version)
An exciter will be in one of the following states :
♦ selected and switched to the RF power amplifiers and hence to air (to antenna); this is the normal
operational state for the transmitter assuming that an automatic changeover has not taken place,
♦ selected but not switched to air; this is the case for an exciter which has been selected but there
has been an automatic exciter changeover,
♦ in reserve; this is the case for an exciter which has not been selected and is not switched to air,
♦ not selected but switched to air; this is the case for the reserve exciter after there has been an
automatic exciter changeover.
In all of these states the exciter can be operational or not.
The operational states of the exciters can be checked in the "EXCITER 1" window on the PCL.
4.5. The two exciter changeover modes
(Dual drive version)
The changeover switch between the two exciters can take place automatically or under manual
control.
♦ In the automatic changeover mode the facilities for an automatic switch between the two exciters
(A
→ B or B → A) if a fault appears on the selected exciter channel have been enabled; in this
mode it is possible to initiate the changeover switch manually.
In the automatic changeover mode the identity of the selected exciter is not changed; this is not the
case with manual changeover.
♦ In the manual changeover the switch can only take place as a result of a command from a user
interface (PCL or remote user interface).
The manual changeover changes the identity of the selected exciter.
The changeover mode which has been selected can be monitored and changed in the "EXCITER 1"
window on the PCL.
At any given time an automatic changeover between the exciters may have taken place, may have not
taken place or may be impossible. The "EXCITER 1" window on the PCL shows which of these three
is the case.
If an automatic changeover has taken place the On-Air exciter has not been selected and hence a
subsequent automatic changeover is impossible. Another automatic changeover can take place if:
♦ a manual changeover has been commanded, or,
♦ a transmitter "RESET" operation is carried out. In this instance care must be exercised because the
records of all cleared faults as well as their consequences to the system will be erased; all
selections effected on the PCL will also be erased.