MITSUBISHI ELECTRONICS AMERICA, INC.
ST200 Series Technical Support Manual
12
January 2000
4.7.1.1 Antenna
The integrated lid Antenna receives signals transmitted from the satellite and transmits signals
provided from the RFU. The OmniQuest
®
Antenna is comprised of a two element planar array
patch antenna integrated into the lid and connected to the OmniQuest
®
Base Unit. The antenna
provides a gain of approximately 10.8 dBic and emits 20 Watts of RF energy nominally in the L
Band frequency range (~1.6 GHz).
WARNING
: Stay 2 feet (24”) / 61 cm away from the antenna while transmitting
The OmniQuest
®
antenna must be manually pointed at the satellite which is aided by using the
Quick Reference Card and compass provided in the standard carrying case. Because the
beamwidth of the antenna is fairly wide (~30
o
), approximate pointing of the antenna is easy.
Once the approximate location of the satellite has been established, the pointing angle can be fine
tuned by using the Received Signal Strength Indicator (RSSI) displayed on the Handset (i.e.,
approximate or initial pointing of the satellite needs only to be accurate enough so that a signal
can received on the RSSI). See section 5.11 for operational considerations concerning the RSSI
and OmniQuest
®
setup.
NOTE:
If an approved external antenna is used, the cable must be securely attached to the
RFU prior to operation. Likewise, if switching from an external antenna back to the
OmniQuest
®
self-contained antenna, the antenna cable must also be securely attached.
Loose or improper connections may render the terminal inoperable (not able to power
on or low received signal) or result in error messages.
4.7.1.2 RF Unit
The RFU is contained within the Base Unit and provides an interface between the OmniQuest
®
antenna and the removable TU. The RFU contains a High Power Amplifier (HPA), Low Noise
Amplifier (LNA), diplexer, and control electronics that provide the proper amplification,
filtering, and control of the RF signals generated from the TU and received from the satellite
through the antenna.
4.7.1.3 Transceiver Unit
The removable TU201A Transceiver Unit is located inside the Base Unit, providing the
necessary interfaces for user devices and the RFU, as well as managing all signaling and
communications with the CGS via the satellite. It demodulates and processes the signals
received by the antenna through the RFU; processes, modulates, and sends signals to the RFU
for transmission, and manages all interfaces with user interface equipment, other connected
accessories, and network interfaces with the CGS.
NOTE:
All required interfaces for the OmniQuest
®
Transceiver Unit are available on the TU
connector panel. Distributors should not attempt to access the electronics inside the
Base Unit without prior authorization from MELA.
!
