JRC NT337-XL2, Instruction Manual

Page: 59 / 187

4-36
4. WT
4.1. WT
4.1.1. Overview
The WT consists of the antenna section, RF section, IF section, digital section, interface section
and power supply.
4.1.2. Antenna section
Uses a Triplate planar antennas to make the antenna compact and to provide a high gain. When
you use an option, you can install a external antenna.
4.1.3. RF section
In the RF section, the transmission IF signals are up-converted into 24-26 GHz-band RF signals
using the local signal, which is generated by multiplying the 2.4 GHz synthesized oscillator. The
next-stage BPF eliminates unwanted sideband components. The up-converted 24-26 GHz-band
RF signals are amplified up to the desired level then fed to the antenna via the TDD-Switch and
the Waveguide Filter.
The received 24-26 GHz-band RF signals by the antenna are fed in to the LNA via the Waveguide
Filter and the TDD-Switch. The output signals of the LNA are down-converted into IF signals
using the local signal, which is generated by multiplying the 2.4 GHz synthesized oscillator. The
BPF is employed to eliminate the image components (interference).
The TDD Switch selects the transmitting or receiving function under the control of TDD/TDMA
framer installed in the WT-ASIC.
4.1.4. IF section
The transmission IF section performs quadrature modulation of 427.5MHz IF frequency according
to the transmission output from the digital modem installed in the WT-ASIC. The SAW filter in
the next stage eliminates undesired out-of-band signals. The output level of the transmission IF
section is adjusted by the automatic transmission gain control (ATPC) function of the digital
modem.
.
In the receiving IF section, the SAW filter eliminates the adjacent channel interference. The
received burst signal level is adjusted by the automatic gain control (AGC) function of the digital
modem. The quadrature demodulator downconverts the received IF signal into the baseband
signal.