User's Manual Part 4

T ECHNICAL D OCUMENTATION P ROTECTING P EOPLE AND A SSETS
®
D
ATE
:
27
M
ARCH
2017
|
V
ERSION
:
1.8
81
R
ANGER
®
-
X5
R
ADAR
S
YSTEM
(M
OBILE
)
F
UNCTIONAL
O
VERVIEW AND
T
HEORY OF
O
PERATION
EEC
®
|
C
OMPANY
P
ROPRIETARY
4.3.3. Radiate Command
Radiate is turned on automatically when EDGE is in the scheduler mode or by command from the
Surveillance screen “Radiate.” Radiate is also available in the LOCAL mode through the LCI screen
at the Control Cabinet console. Before the RCU will initiate a “radiate on” command, the system
must meet all software tx_interlock conditions, and the radar must be in a STANDBY status. The
RCU will initiate a “radiate on” command when commanded to radiate by the EDGE Software.
4.3.4. IF to RF Signal Up and Down Conversion
The Up-down converter (UDC) / Transmiter Control for the Ranger-X5 radar translates information
between the intermediate frequency (IF) and X-band operating frequencies. It is a high performance
unit which greatly reduces the size, weight and complexity of a microwave transceiver subsystem in
weather radar, while maintaining excellent performance characteristics. The UDC / Transmit Control
system provides the local oscillator signals to both the up-converter and down-converter and utilizes
other components, such as filters, low-noise amplifiers (LNA), and RF Amplifier all integrated in the
same RF assembly.
A pulsed waveform produced by the IQ2 at the IF frequency of 60MHz drives the up converter, which
translates the signal to the desired X-band frequency. A range of RF values are available to select
as the up converter output, ranging from 9.2 to 9.7GHz with 20MHz resolution and controlled through
a serial interface. An on-board PLL and frequency synthesizer utilizes the 100MHz reference
oscillator signal and provides the LO to the single stage mixing network. Similarly, the down
conversion block mixes the RF signal with the LO to produce the 60MHz IF signal, then is passed
to the IQ2 for base band digitization. Prior to the RF input on the down conversion stage, a pre-
amplifier network ensures that the dynamic range of the transmitter assembly block is matched to
the input of the digital receiver, maximizing the capabilities of the system.
The UDC is a breakthrough in achieving excellent performance of image rejection (without narrow
band filters in the module or multiple conversion states), TR isolation, and phase noise in an
integrated module. This UDC design combines a very simple single-stage conversion structure and
image-rejection mixer technology, which achieves strong image rejection performance without
onboard filters or multiple stages of conversion. This technology also helps reduce complexity and
minimize space requirements. The shielded RF enclosure helps to achieve the required level of TR
isolation. The PLL circuitry gives the phase noise performance and frequency agility, which are
normally available only in much more complex microwave signal sources. This also enhances the
radar system performance such as clutter visibility and Doppler accuracy.
4.3.5. Fiber-Optic Rotary Joint
The Fiber-Optic Rotary Joint provides the transition Fiber Optic cable transmission through the
azimuth axis.
4.4. Receiver Signal Flow
The Ranger-X5 receiver (see Figure 67) is fully contained within the Payload Support Assembly on
the Pedestal. It is an integral part of the UDC and includes the UDC and IQ2-IFD.
4.4.1. IQ2-IFD
The IQ2-IFD receives the horizontal and vertical receive IF from the two UDCs. The IQ2-IFD digitizes