Jackson Labs RSR GNSS Transcoder, Руководство пользователя

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RSR GNSS Transcoder™ User Manual
12 © 2017 Jackson Labs Technologies, Inc.
typical 8th-generation target GPS receivers. This low RF power level avoids accidental
re-broadcasting of signals through faulty (leaky) antenna coax cables, and it closely imitates the
signal levels that a typical industry-standard active GPS antenna with a good view of the sky would
present to a GPS receiver. The RF output power level is adjustable through standard SCPI user
commands for further fine-tuning ability.
To enhance the capabilities of the unit, a 9-degrees-of-freedom (9-DOF) MEMS IMU is integrated
into the board that is used to create intermediate position- and velocity-fixes up to 10Hz and more,
and an optional CSAC is used to provide exceptional timing accuracy even during extended holdover
(flywheel) events during which the external GNSS receiver or 1PPS reference is not able to provide
a PVT fix. The RSR GNSS Transcoder™ also includes an internal GPS receiver that continuously
monitors the RF output signal on the SMA connector for signal strength and PVT/PNT fix quality.
3.2 Operating the Unit
The RSR GNSS Transcoder™ is physically designed to fit, and be mounted below a Rockwell RSR
SAASM Puck. An optional IP67-rated water-proof enclosure is available for vehicle mounted or
desktop applications. It can also be used as a stand-alone unit without external GNSS receiver.
Stand-alone use with the optional CSAC installed on the unit allows time-transfer to any GPS
receiver with nanoseconds accuracy and CSAC Atomic Clock holdover performance. Power can be
applied through the USB port, or through the Avionics-compatible 7V to 36V DC power port. Please
note that the unit will typically generate an RF output shortly after power is applied. The RF output
connector of the unit does not need to be terminated if unused, however it is recommended to
terminate the output to avoid leakage of GPS RF signals out of the coax connector.
The unit is available in a special-order variant from Rockwell Collins with a molded enclosure that
conforms to the Rockwell RSR Puck outline, or as a standard PCB module.
3.2.1 USB Control and Power
The integrated mini-USB connector can be used to power the RSR GNSS Transcoder™ from
external industry-standard USB battery sticks, USB Wall-Wart supplies, or from a PC. The allowable
voltage range for USB power is 2.7V to 5.6V with 5V nominal. Power consumption is low at less
than 1.2W, allowing extended operating times with small batteries. The unit will also show up as a
standard USB serial port when plugged into a PC (the integrated Si2104 USB interface chip drivers
can be downloaded from the Silicon Labs and/or JLT website), and can be controlled by GPSCon or
a terminal program at 115,200 Baud, 8N1, with no flow-control. The GPSCon Windows application
can be downloaded from www.jackson-labs.com. Typical power consumption through the USB port
is about 1.18W at 5V without the CSAC option, and about 1.35W with the CSAC option.
3.2.2 DC Power supply: 7V to 36V
An alternative way to power the unit other than through the USB port is to use the DC power input
port. The RSR GNSS Transcoder™ includes a vehicle and avionics-compatible DC-DC switching
power supply with noise filtering. DC Prime power is applied to pin 2 of connector J4, and ground
applied to pin 4 of J4. The allowable voltage range on this DC power port is 7V to 36V, with a
nominal voltage of 12V. The unit can be alternatively powered by the USB port, or from the DC port,
or from both at the same time. The USB port is diode-protected from back-feeding power from the
internal DC-DC switcher when operating from the 7V to 36V supply. Typical power consumption of