Linear AT7120, Руководство пользователя, Страница: 19 / 76

AT7120 Owner Manual Rev. 1.1
– March 2009 19/76
Lack of lock voltage of the PLL at the Up-converter - Module 4492.
Excessive temperature of the 60W UHF amplifier - Module 4407 – (above 65ºC).
Excessive reverse power (above +4V at CON-9).
Overflow of the FIFO register in the 8VSB modulator (communication between microcontroller
and modulator).
Failure of synchronization of the transport data (MPEG) stream
Presence of non-programmed hardware (a false alarm may present during the warm-up phase of
the equipment).
Imperfections associated with the generation of master clock signal in the modulator 8VSB -
Module 4549.
Nominal operation of the equipment pr5Vdc on the alarm pins on CON-4 and CON-6; CON-5
indicates that there is no alarm condition. An alarm state is indicated by a voltage of less than 5 VDC.
In most cases the alarm state will present zero volts dc to the associated connector. The microcontroller
(CI-4) will inhibit transmission during an alarm state.
The alarms generated in the system are shown in the LCD display of the MCU. The corresponding
indication for these alarms are “*” for active alarms - - and “#” for previous alarms (an alarm state that
has been resolved or that has ended.) - PAST. The occurrence of an alarm “*” will automatically end the
transmission. When the reason for this alarm “*” is resolved, a symbol “#” will appear and the
transmission will be restored automatically. To erase old alarms, just press the “CLR.ALL” key on the
front panel of the equipment or when using a hyper-terminal press “1” on the keyboard.
Communication with 8VSB modulator
The CIP8231 board communicates with the 8VSB modulator - Module 4549 - through a set of serial
port interfaces (SPI). These SPI’s are located on pins 2 to 5 of connector CON-3 and on pins 5 and 6 of
connector CON-5.
The communication between CIP8231 board and the 8VSB modulator - Module 4549 - monitors and
sets the configuration parameters of this module. For example, the adjustment of the pilot programming
stream (the 8VSB signal), and adjustment of the superior lateral band rejection are managed over this
communication interface.
Setting the FCC/UHF operational channel
The operational channel of the equipment is set via the CIP8231 board. The board generates a code that
represents the selected channel (UHF) which is then sent over the SPI to the up-converter - Module 4492
- This stream of information is composed by data, clock and enabling code, and is presented on pins 1, 2
and 3 of connector CON-4 of the CIP8231 board.