Microwave Radio Communications LLC PTX127T1CG User Manual
Theory of Operation
8-2
PTX-PRO User and Technical Manual
All PTX-PRO configurations are available with Standard
Definition (SD) or SD and optional High Definition (HD) video
technologies.
Definition (SD) or SD and optional High Definition (HD) video
technologies.
The PTX-PRO can accept a wide variety of signal formats and
includes an RF up-converter for use in transporting signals over
a microwave link. The PTX-PRO also contains an MPEG/
COFDM module.
includes an RF up-converter for use in transporting signals over
a microwave link. The PTX-PRO also contains an MPEG/
COFDM module.
The PTX-PRO contains a universal power supply and can
operate on 90 to 264 VAC, 50/60 Hz or +11.0 to +36.0 VDC.
operate on 90 to 264 VAC, 50/60 Hz or +11.0 to +36.0 VDC.
8.3
System Theory of Operation
The PTX-PRO is comprised of the following primary
components:
components:
•
Command and control universal power supply module
•
MPEG encoder/COFDM modulator module
for a block diagram of the 13 GHz
PTX-PRO.
The PTX-PRO also contains the IF/RF module which accepts
either a 70 MHz COFDM or external 70 MHz input signal and up-
converts these signals to the 13 GHz RF band. The PTX-PRO
can therefore serve as a standalone digital video microwave
transmission system.
either a 70 MHz COFDM or external 70 MHz input signal and up-
converts these signals to the 13 GHz RF band. The PTX-PRO
can therefore serve as a standalone digital video microwave
transmission system.
The RF frequency synthesizer circuit included in the IF/RF
module, along with the command and control module, provide
the means to channelize RF video and audio signals in the 13
GHz RF band. Standard U.S. FCC band plans, as well as
custom channel plans, may be accommodated using the MRC
Radio Configurator (Configurator), when the Configurator
software is connected to the PTX-PRO.
module, along with the command and control module, provide
the means to channelize RF video and audio signals in the 13
GHz RF band. Standard U.S. FCC band plans, as well as
custom channel plans, may be accommodated using the MRC
Radio Configurator (Configurator), when the Configurator
software is connected to the PTX-PRO.
8.3.1
Command and Control Power Supply
The PTX-PRO command and control power supply modules
contain external and internal communications circuitry, as well as
supplying necessary system voltages.
contain external and internal communications circuitry, as well as
supplying necessary system voltages.
The PTX-PRO power supply accepts a wide range of DC input
voltages (+11.0 to +36.0 VDC) or 90 to 264 VAC, 50/60 Hz. The
supply converts the input voltage to the DC voltages required by
the rest of the PTX-PRO circuits and distributes the appropriate
output voltages to the various circuits.
voltages (+11.0 to +36.0 VDC) or 90 to 264 VAC, 50/60 Hz. The
supply converts the input voltage to the DC voltages required by
the rest of the PTX-PRO circuits and distributes the appropriate
output voltages to the various circuits.
The on-board microprocessor manages the system configuration
and operation of all modules to which it is connected, e.g.,
MPEG/COFDM, IF/RF modules, etc.
and operation of all modules to which it is connected, e.g.,
MPEG/COFDM, IF/RF modules, etc.
This ensures that the PTX-PRO can permit switching modes of
operation, change system Presets, etc. Therefore, system
control may be accomplished using front panel control or remote
control.
operation, change system Presets, etc. Therefore, system
control may be accomplished using front panel control or remote
control.
8.3.2
MPEG/COFDM Encoder/Modulator Module
The MPEG/COFDM module is the heart of the PTX-PRO digital
mode circuitry. This circuit may be configured to accept a wide
range of digital or analog video and audio signal inputs and
provide COFDM IF (70 MHz) video signal outputs.
mode circuitry. This circuit may be configured to accept a wide
range of digital or analog video and audio signal inputs and
provide COFDM IF (70 MHz) video signal outputs.
The various signal inputs and outputs are connected through the
PTX-PRO combiner circuit where they are switched under
software control.
PTX-PRO combiner circuit where they are switched under
software control.