108
analog to digital transmission. Current fourth-generation (4G LTE) wireless mobile
telecommunications technology allows high-speed mobile ultra-broadband data
transmission in bands extending to 2100 MHz. Specialized data modems known as
cell data radios transmit and receive data using 3G protocols through the so-called
EDGE-GSM system, where GSM is the 2G European telecommunications standard
and EDGE is a backward-compatible 3G enhanced data-rate protocol employing
the advanced Eight Phase Shift Keying (8PSK) phase shift modulation scheme.
Eight 45° signal phase shifts are allowed, each carrying 3 data bits. High-speed
internet protocols (3G, 4G LTE) allow command and control with visual display of
the data output (Fig. 2.6) from remotely operated onsite computers as is used for HF
radar installations.
5.2.3 Cable Connections for Coastal Ocean Observing
Cable connections of subsurface instruments to surface communications platforms
in shallow waters are common. For buoy applications, instruments may be mounted
within specialized steel cages physically incorporated into the buoy mooring system
(Fig. 3.2). Power and communication cables are fairlead along the mooring cable to
waterproof bulkhead connectors mounted on the payload bay housing.
Cabled shore-piercing systems are in use at some of the research installations
discussed above such as LEO-15 off the New Jersey coast and the Martha’s Vineyard
Observatory off the eponymous island of the coast of Massachusetts. While they are
extremely reliable and their operational costs are modest, initial costs of cable
installation are largely prohibitive. Exposed cables crossing the shoreline are hazardous and subject to significant abrasion in the high energy (Pierce and Romanelli
1969) surf zone and are banned in many jurisdictions. An alternative, more environmentally sound installation entails directional drilling to tunnel beneath the shoreline zone, an effective but expensive technology common to the fossil fuel industry.
Such installations normally require official permits from various government agencies, a lengthy process in most cases.
5.3 Acoustic Data Links for Coastal Ocean Observing
The seawater medium is largely opaque to electromagnetic radiation in the frequencies commonly used for radio communicationns (3 kHz to 300 GHz) with the
exception of the extremely low frequency band (ELF 3–30 kHz). Naval submarines
rely on this band for communications to depths of around 100 m and ranges of up to
10,000 km. However, the low frequency results in low data density allowing only
brief communications such as a commmand to raise a conventional surface-piercing
5 Signal Conditioning, Data Telemetry, Command Signaling and Platform Positioning…
analog to digital transmission. Current fourth-generation (4G LTE) wireless mobile
telecommunications technology allows high-speed mobile ultra-broadband data
transmission in bands extending to 2100 MHz. Specialized data modems known as
cell data radios transmit and receive data using 3G protocols through the so-called
EDGE-GSM system, where GSM is the 2G European telecommunications standard
and EDGE is a backward-compatible 3G enhanced data-rate protocol employing
the advanced Eight Phase Shift Keying (8PSK) phase shift modulation scheme.
Eight 45° signal phase shifts are allowed, each carrying 3 data bits. High-speed
internet protocols (3G, 4G LTE) allow command and control with visual display of
the data output (Fig. 2.6) from remotely operated onsite computers as is used for HF
radar installations.
5.2.3 Cable Connections for Coastal Ocean Observing
Cable connections of subsurface instruments to surface communications platforms
in shallow waters are common. For buoy applications, instruments may be mounted
within specialized steel cages physically incorporated into the buoy mooring system
(Fig. 3.2). Power and communication cables are fairlead along the mooring cable to
waterproof bulkhead connectors mounted on the payload bay housing.
Cabled shore-piercing systems are in use at some of the research installations
discussed above such as LEO-15 off the New Jersey coast and the Martha’s Vineyard
Observatory off the eponymous island of the coast of Massachusetts. While they are
extremely reliable and their operational costs are modest, initial costs of cable
installation are largely prohibitive. Exposed cables crossing the shoreline are hazardous and subject to significant abrasion in the high energy (Pierce and Romanelli
1969) surf zone and are banned in many jurisdictions. An alternative, more environmentally sound installation entails directional drilling to tunnel beneath the shoreline zone, an effective but expensive technology common to the fossil fuel industry.
Such installations normally require official permits from various government agencies, a lengthy process in most cases.
5.3 Acoustic Data Links for Coastal Ocean Observing
The seawater medium is largely opaque to electromagnetic radiation in the frequencies commonly used for radio communicationns (3 kHz to 300 GHz) with the
exception of the extremely low frequency band (ELF 3–30 kHz). Naval submarines
rely on this band for communications to depths of around 100 m and ranges of up to
10,000 km. However, the low frequency results in low data density allowing only
brief communications such as a commmand to raise a conventional surface-piercing
5 Signal Conditioning, Data Telemetry, Command Signaling and Platform Positioning…