|
The
Omnitech Electronics SM73 MDDS (Meteorological Data Distribution
System) is a meteorological measurement system for shipboard
installations. The MDDS was designed for the Canadian Navy’s Halifax Class ships but can be customized by Omnitech for almost any
application.
The MDDS measures air temperature, barometric
pressure, relative humidity and seawater temperature.
Additionally, it receives
digital inputs from the ship’s existing port and starboard wind
detector units and GPS receiver. This measured data is processed
and distributed to various shipboard systems. The SM73 MDDS
consists of three system components:
1.
The SM73-ADAS (Paroscientific MET3A) meteorological sensor
- to measure air temperature, barometric pressure and relative
humidity. This measured data is transmitted digitally to the MDDS
Display Unit using RS-422 protocol. Omnitech selected the MET-3A
for its outstanding accuracy, long term stability and rugged
construction suitable for shipboard installation.
2. The SM73-TS temperature sensor - to measure sea water
temperature and transmit this data using an analog 4-20 mA current
loop to the MDDS Display Unit.
3. The SM73 MDDS Display Unit - to monitor the digital and
analog signals from the SM73-ADAS and SM73-TS sensors. The display
unit also accepts inputs from the ship’s port and starboard wind
sensors and GPS receiver. The display unit processes this input
data and calculates the required meteorological output data for
distribution to the ship’s METS computer. The user interface
consists of a 40 character by 2 line LCD and a 16-button keypad
that together allow the user to view the meteorological data and
configure the various MDDS operating parameters. A simple menu
system guides the user through the operating modes and calibration
routines for each sensor. Should a sensor fail, it can be disabled
easily and manual sensor data can be entered to allow down stream
systems to continue to function. The MDDS display unit is
contained in a 19” wide by 2U high rack mount enclosure.
The
Display Unit transmits port and starboard wind speed and wind
direction, air and sea water temperature, barometric pressure and
relative humidity to the ship’s METS computer using a
proprietary MIL-STD-188C protocol once per second. It also outputs
relative and true wind speed and wind direction, sea water
temperature, air temperature, relative humidity, barometric
pressure, dew point temperature, ship’s latitude, longitude,
speed and heading, UTC and date in NMEA-0183 version 2.3 format. The
Display Unit includes a non-volatile data-logging capability to
record meteorological data for the previous seven days - recorded
at half-hour intervals. This data can be output
as NMEA-0183 messages for capture and/or viewing.
This article is submitted by
Omnitech
Electronics Incorporated
10
Akerley Boulevard
Dartmouth
,
Nova
Scotia
,
Canada
,
B3B 1J4
Tel: 902-468-5911 Fax: 902-468-5912
|
