ViaSat VMBR-1520, Installation, Operation And Maintenance Manual, Page: 25 / 88

VMBR-1520 Mobile Broadband Router Installation, Operation, and Maintenance Guide
General Description
Rev. 001 1075152
1-7
Power Distribution
The Power Supply accepts universal AC input - 100 VAC - 240 VAC,
50 Hz - 60 Hz, at a maximum current of 3 ampere. It is protected by a
250 V, 3 A, time-lag, circuit breaker which is part of the front panel AC
power switch. The AC switch controls the application of AC to the
Power Supplies. The Backplane uses Point-of-Load regulators to
convert the Power Supply output to the necessary DC voltages for
internal components.
Reference Signal
The VMBR-1520 contains a high-precision internal master reference for
all internal components. The reference is self contained and does not
require any configuration, calibration, or maintenance.
The VMBR-1520 provides a 10 MHz sine wave reference signal for the
BUC through the Tx RF port (J2), and for the LNB through the Rx RF
port (J3). The specifications for both reference signals can be found in
Table 1-2.
TXR
The TXR provides the transmit function for the Return Link, and also
serves as the command and control center of the modem. The
incoming user data enters the TXR through the User Ethernet port (J8).
User data comes in the form of TCP/IP packets. The TXR processes the
packets into a baseband data stream. The baseband data goes through
Forward Error Correction (FEC) encoding, filtering, symbol mapping,
and digital-to-analog (D/A) signal conversion. The D/A outputs, which
contains the in-phase (I) and quadrature (Q) analog waveforms, go
through a quadrature modulator to be upconverted to L-Band. The L-
Band Tx RF signal is then multiplexed with a 10 MHz reference and DC
power for the BUC before being applied to the Tx RF port (J2).
As the command and control center of the modem, the TXR configures
and controls the Forward and Return Link parameters, such as
frequency, data rate, etc. It also monitors the condition of the modem
and alerts the user in case of a fault condition.
Initial configuration and diagnostics of the modem is provided through
the console port (J5) on the TXR.
LFLR
The LFLR provides the receive function for the Forward Link. The
Forward Link is received from the antenna and passed to the modem as
an L-Band signal through the Rx RF port (J3). The Rx RF signal is
demodulated into baseband in-phase (I) and quadrature (Q) analog
waveforms. The I and Q signals go through analog-to-digital (A/D)
conversion, symbol mapping, filtering, FEC decoding, and re-
construction back into TCP/IP packets. The packets are transmitted to
the TXR where they will be sent to the user via the User Ethernet port
(J8). A 10 MHz reference and +18/12 V DC are provided to the antenna
LNB through the Rx RF port (J3).
Receive Signal Strength Indicator (RSSI) is provided by the LFLR to the
ACU through the ACU EIA-422 port (J4).