Tektronix RTX100B, Service Manual

Page: 42 / 178

Theory of Operation
2-4
RTX100B ISDB-T RF Signal Generator Service Manual
A150 ISDB-T RF Output Board
The A150 ASI ISDB-T RF Output board consists of the following blocks:
The local bus interface communicates with the A12 Main board. There are two
sets of 16-bit signal lines for Rx and Tx: 8-bit data lines for single-end connec-
tion, 4-bit control lines for single-end connection, and 4-bit control lines for
differential connection. These lines are connected to the A12 Main board in
one-on-one.
This block changes an ASI signal received from the ASI In connector into
parallel transport stream data.
This block changes parallel transport stream data into an ASI signal and output
the signal.
This block consists of an FPGA of ALTERA. It is the interface for PCI and
interchange of an incoming transport stream signal. It also generates an interrupt
signal when an IIP of a transport stream is decoded and Mode is changed.
This block performs coding of ISDB-T. It has four synchronous SRAMs as
buffers for interleaving.
This block performs OFDM modulation using IFFT.
This is a digitally controlled PLL, which synchronizes the reference clock
(VCXO) with an internal reference clock or an external clock. This block has a
feature to pass the U600 output to U1100.
This block converts OFDM modulated data to an analog signal. It has an over-
sampling circuit and digital filter for reducing spurious events. The block also
has two A/D converters for I and Q signals.
This block generates a carrier signal for the RF output. It directly generates a
career frequency of UHF.
This block performs I/Q modulation to a carrier signal from the A/D converter
output.
Local Bus Interface
ASI RX and ASI Decoder
ASI Encoder and ASI TX
PCI Interface FPGA
Channel Coding FPGA
OFDM Modulation FPGA
Digital PLL FPGA
RF DAC
RF Carrier Synthesizer
Quadrature Modulator