Axcera CHV400BTD, Техническое руководство

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Innovator CHV400BTD ATSC Transmitter Board Descriptions
Technical Manual, Rev. 0 51
The FPGA subsequently provides error signals to an analog phase locked implemented
with op amp stages U45-A, B and C. The output of these compensation stages is used
as the control voltage to the VCXO, U37. The phase locked output of U37 is applied to
an analog filter to remove harmonics of the pilot and then input to the quadrature
splitter Z1. The outputs of Z1 are used as the inputs to the mixers in the analog output
section.
Voltage Requirements
The ±12 VDC and +5VDC needed for operation of the board connect to J1 on the Power
Conditioner Board (1309404) which delays the +5VDC so that the ±12 VDC to the 8 VSB
Modulator Board is applied first. The voltage output of the power conditioner board is at
J2 that is jumpered to J30 on the 8 VSB modulator board.
The ±12 VDC connect to the 8 VSB modulator board at J30-1. The +12V SYS connects to
J18A, B & C and to regulator circuits. The +12V SYS is filtered by L2, L3, C105 and C106
before it is applied to the rest of the board as +12VQ and +12VI. The -12 VDC SYS
connects to J19A, B & C and to regulator circuit. The -12V SYS is filtered by L6, L7, C111
and C112 before it is applied to the rest of the board as -12VI and –12VQ.
The +12V SYS also connects through the resistor R81 to p5V EXT to the rest of
the board, and to the regulators U23 that pr3.3V to the rest of the board and to
U27 that pr1.8V output. The +3.3V also connects to U24 that su1.5V
output. The +12V SYS connects to the regulator U25 and U26 to supply the +5VA output.
The output of U25 also connects to U28, which provides the +5V output to the rest of the
board. +12V SYS is filtered by L4 and C107 to provide the +12V output to the board.
The –12V SYS also connects to the regulator U22 that provides the –5V VA to the rest of
the board. -12V SYS is filtered by L5 and C108 to provide the -12V output to the board.
J2
IF Input
0 dBm Pk Pwr
Pin
Attenuator
In Phase In Phase Splitter
Quad Quad Quad
Combiner
Amplitude and Phase Correction
Input and
Modulation
Detectors
Input Fault
Indicator
Video Loss
Indicator
Front Panel
ALC
Input
Fault
Modulation
Loss
Level
Detector
TP1 = 1V
Frequency
Response
Corrector
Frequency
Response
Corrector
Frequency
Response
Corrector
J1
IF
Output
(A3) IF Pre-Corrector Board (1308796)
The IF Pre-Corrector Board provides ALC, automatic or manual, gain control of the IF
level. The board also supplies pre-correction Response, In Phase and Quadrature Non-