User's Manual

Innovator CU0TD-1/CU0RD-1 – CU4TD/CU4RD Board Descriptions
ATSC Transmitter/Regenerative Translator
Instruction Manual, Rev. 1 57
MHz are divided down to a common frequency, which is then compared internal
to the FPGA. 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 provide +5V EXT to the
rest of the board, and to the regulators U23 that provides +3.3V to the rest of the
board and to U27 that provides +1.8V output. The +3.3V also connects to U24
that supplies +1.5V 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.
(A5) ALC Board, Innovator CX Series (1315006 or 1308570)
The ALC Board, Innovator CX Series, is used to control the RF drive power to the RF
amplifier chain in the CU0TD/RD-1 thru CU0TD/RD-5 systems. The board accepts an 8-
VSB RF input signal at a nominal input level of -3 dBm average power and amplifies it to
whatever drive level is necessary to drive the final RF amplifier in the drawer to full
power. The input signal to the board at J1 is split by U4, with one half of the signal
driving a PIN diode attenuator, DS1 and DS2, and the other half driving a detector, U13,
that is used to mute the PIN attenuator when there is no input signal. The output of the
PIN attenuator is sent to two cascaded amplifiers, U2 and U3, which are capable of
generating +10 dBm average power from the board at J2.
The PIN attenuator is driven by an ALC circuit or by a manual fixed voltage bias,
depending on the position of switch S1. When the switch is pointing to the left, looking
from the front of the drawer, the ALC circuit is enabled. When the switch is pointing to
the right, the ALC circuit is disabled and the PIN attenuator is controlled through the
Manual gain pot R62. When the switch is in either ALC or manual, the voltage in the
unused circuit is preset low by the circuitry connected to pins 4-6 on SW1. This allows
the RF power to ramp up slowly to full power when the switch changes positions. CR8,
C33 and associated components control the ramp up speed of the manual gain circuit.