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transmission in its area of coverage. Two operational geostationary satellites centered above the equatorial Eastern Atlantic and the Indian Oceans provide 11 international channels (402.0355–402.0685 MHz) and 234 regional channels
(402.0685–402.435, MHz) in the HF band (EUMETSAT 2013). The Japanese
Himawari 8 geostationary weather satellite operated by the Meteorological Satellite
Center of the Japan meteorological Agency receives DCP data through its international channel at 402.0–402.1 MHz and domestic channel 402.1–402.4 MHz. Data
is transmitted to ground segments in the radar Ka-band at 18.1–18.4 GHz.
The GLOBALSTAR system is a commercial constellation of satellites in low
earth orbit at an altitude of about 1400 km with a 114 min orbit period. Following
degradation of communications in the S-band amplifiers of the first generation, a
second generation of 24 satellites in 8 orbital planes with improved communications
capability was placed in orbit and is operational as of 2013. Forty ground receiving
stations complete the communications network. For data transmission from remote
locations, GLOBALSTAR offers uplink communications to the satellite within 1610
and 1625 MHz in the MF radio band and downlink communications to receiving stations within 2483.5–2500 MHz microwave band. GLOBALSTAR electronic modules (databoards), in addition to providing a data link, provide GPS reception
allowing platform tracking through this satellite network. Coastal area coverage is
provided for the Americas, Europe, Australia and Japan.
The IRIDIUM system is also a commercial satellite constellation that provides
global voice and data transmission. The 68 operational satellites in this constellation
orbit an altitude of approximately 780 km. In contrast to the GLOBALSTAR constellation which exhibits orbits inclined at 52°, IRIDIUM satellites use polar orbits
allowing coverage within the Polar Regions. With 66 satellites in 6 orbital planes,
IRIDIUM operates user links for DCPs within 1618.85 and 1626.5 MHz in the HF
radio band. A second generation of 66 operational satellites operating in the L radar
band is expected to be in place by 2020. IRIDIUM satellites communicate with four
neighboring satellites within the constellation in band between 22.55 and 23.55 GHz
allowing flexible communication relays.
5.2.2 Cellular Network Data Transmission for Coastal Ocean
Observing
Platforms generating low data density such as ODAS buoys communicate over cellular networks using the Global System for Mobile communications (GSM) system,
an international standard data transmission technology operating in the bands
between 300 and 1900 MHz. Since higher power output (up to 20 W) than that
allowed for cell phones is allowed for GSM radios operating at these frequencies,
transmission range is extended. Maximum GSM range is quoted at about 35 km.
Cellular communications networks are today fully digital, in large part, to facilitate
data transmission. The development of the fully digital GSM protocols (also known
as 2G to differentiate it from the first analog generation) primed the transition from
5.2 Electromagnetic Data Transmission for Coastal Ocean Observing
transmission in its area of coverage. Two operational geostationary satellites centered above the equatorial Eastern Atlantic and the Indian Oceans provide 11 international channels (402.0355–402.0685 MHz) and 234 regional channels
(402.0685–402.435, MHz) in the HF band (EUMETSAT 2013). The Japanese
Himawari 8 geostationary weather satellite operated by the Meteorological Satellite
Center of the Japan meteorological Agency receives DCP data through its international channel at 402.0–402.1 MHz and domestic channel 402.1–402.4 MHz. Data
is transmitted to ground segments in the radar Ka-band at 18.1–18.4 GHz.
The GLOBALSTAR system is a commercial constellation of satellites in low
earth orbit at an altitude of about 1400 km with a 114 min orbit period. Following
degradation of communications in the S-band amplifiers of the first generation, a
second generation of 24 satellites in 8 orbital planes with improved communications
capability was placed in orbit and is operational as of 2013. Forty ground receiving
stations complete the communications network. For data transmission from remote
locations, GLOBALSTAR offers uplink communications to the satellite within 1610
and 1625 MHz in the MF radio band and downlink communications to receiving stations within 2483.5–2500 MHz microwave band. GLOBALSTAR electronic modules (databoards), in addition to providing a data link, provide GPS reception
allowing platform tracking through this satellite network. Coastal area coverage is
provided for the Americas, Europe, Australia and Japan.
The IRIDIUM system is also a commercial satellite constellation that provides
global voice and data transmission. The 68 operational satellites in this constellation
orbit an altitude of approximately 780 km. In contrast to the GLOBALSTAR constellation which exhibits orbits inclined at 52°, IRIDIUM satellites use polar orbits
allowing coverage within the Polar Regions. With 66 satellites in 6 orbital planes,
IRIDIUM operates user links for DCPs within 1618.85 and 1626.5 MHz in the HF
radio band. A second generation of 66 operational satellites operating in the L radar
band is expected to be in place by 2020. IRIDIUM satellites communicate with four
neighboring satellites within the constellation in band between 22.55 and 23.55 GHz
allowing flexible communication relays.
5.2.2 Cellular Network Data Transmission for Coastal Ocean
Observing
Platforms generating low data density such as ODAS buoys communicate over cellular networks using the Global System for Mobile communications (GSM) system,
an international standard data transmission technology operating in the bands
between 300 and 1900 MHz. Since higher power output (up to 20 W) than that
allowed for cell phones is allowed for GSM radios operating at these frequencies,
transmission range is extended. Maximum GSM range is quoted at about 35 km.
Cellular communications networks are today fully digital, in large part, to facilitate
data transmission. The development of the fully digital GSM protocols (also known
as 2G to differentiate it from the first analog generation) primed the transition from
5.2 Electromagnetic Data Transmission for Coastal Ocean Observing