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General Description
The Model 1800A is a microprocessor-controlled,
frequency agile transceiver. Its transmitter and receiver
can access all FCC assigned multipoint radio frequency
pairs. The radio's completely redundant architecture
also includes a duplexer, an internal battery, and automatic/manual
changeover capabilities. All of this comes in a case
that occupies only 5.25 inches of rack space. The master
station may operate as the status, diagnostic, and/or
control center for a multiple address radio system.
Also, a technician using the available Alligator Advanced
Diagnostic Software may routinely diagnose and calibrate
all Alligator remote radios over-the-air.
Applications
- Utility Data Communications
- Railroad Data Communications
- Oil and Gas Pipeline Monitoring
- Water and Wastewater Systems
- SCADA & Distribution Automation
Implementation
Alligator designed the Model 1800A radio to operate
as the master station of a Multiple Address Radio System
(MARS). Such radio systems are commonly used for remote
data acquisition and systems control. A typical radio
system would include a single master station and multiple
remote radios. The master station connects to a local
data acquisition computer or systems controller either
directly, via telephone line, or via microwave link.
A 4-wire VF interface module is available to simplify
installation of remotely monitored Model 1800A radios.
Each remote radio connects to a Remote Terminal Unit
(RTU) that collects data or enacts received control
signals. This radio network forms the basic model of
a Supervisory Control and Data Acquisition (SCADA) system.
More complex systems include multiple master stations,
repeaters, or polling remotes. The Model 1800A radio
is configurable to fulfill each one of these roles.
Automatic TX A/B Cycling
The transmitter modules can be programmed to switch
over automatically at fixed intervals and times. This
allows either transmitter module to act as a primary
unit at a 50% operating cycle. This procedure extends
the life expectancy of both modules and the entire radio.
Redundant High Stability Time Base
This optional feature supplies two separate time
bases, each with 0.15 PPM frequency stability. These
are used to provide approximately 10 years of on-channel
operation without having to calibrate the frequency.
One time base operates as primary, and the other operates
as redundant backup. Switch-over is automatic. This
optional feature is very beneficial when used in conjunction
with remote radios equipped with AGFC, where all remote
radios automatically calibrate their time base to match
the master radio time base.
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Common Time Base
The Model 1800A Master Station operates on a single
TCXO time base. The advantage of a single TCXO is that
there is no offset between the transmit and receive
modules within the master station. With all the remote
radios in the Automatic Global Calibration mode, the
entire MAS radio network is at zero frequency offset.
For redundant masters, a second TCXO with automatic
switchover capability is provided.
Hot-Warm Standby
This transmitter switchover scheme eliminates the
unwanted effects of a hot-standby system and combines
the advantages of the warm-standby system. The Hot-Warm
Standby master consumes less power, prolongs the life
of the RF power amplifier, has faster switchover time,
eliminates the notorious beat tone generated by two
active transmitters in a hot-standby system, and alerts
the operator of a failed standby unit before it is too
late.
Dial-Up Auto Answer
The master station diagnostics channel can be directly
connected to any phone outlet without the use of a modem.
With a dial-up interface module connected between a personal
computer and any phone outlet, a technician can dial up
any master station to perform diagnostics of the master
and remote radios, as well as perform controlling functions
of remotes and repeater stations.
With this feature, the factory can assist system set-up
or trouble shooting by dialing up the master station
directly from the factory. As an added bonus, there
is no need to remove remote radios from the sites to
upgrade future firmware enhancements. Alligator can
dial up the master from the factory and upload the new
software options to every remote radio and repeater
station.
Frequency Agile / Auto Channel Select
Over 1 MHz of frequency-synthesized range is available
in increments of 6.25 kHz. This covers all wide or narrow
channels within the authorized MAS frequency band. Using
a diagnostics computer, a technician can program the frequency
synthesizers to any of the FCC-approved 12.5 or 25.0 kHz
channels within a matter of seconds, without opening the
radio or any of its TX/RX modules. A single TX or RX module
can be used to back up any number of master radios. After
a defective module is replaced, the newly installed replacement
module will be automatically set to the assigned operating
frequency of that master station. There is no need to
look up the frequency assigned to a specific master station
or use sophisticated test equipment to re-tune the system. |
