Maritime satcom: More providers, more options to meet an expanding world of needsJul 27, 2016 10:21 AM
Courtesy Iridium Communications
The newest generation of Iridium satellites are the Iridium NEXT, scheduled for launch this year. Like the current Iridium constellation, the NEXT satellites will have crosslink communications capability.
Trends in land-based and space-based communications seem to have gone in different directions. Land-based cellular coverage has become nearly ubiquitous — a commodity with just a few providers offering nearly identical coverage networks. Marine satellite communication, however, has become a more complicated area as satcom choices have multiplied. Unlike cellphone communication, finding the right maritime satcom provider and package is highly dependent on an organization’s communications needs.
In the old days, commercial maritime satcom meant Inmarsat. It was the only provider of satellite communications for marine applications. For users who needed a simple, text-based, store-and-forward system, there was Inmarsat C. For any type of satellite telephony, however, a stabilized dish antenna was required. The physics of the satellites and the frequencies used meant that the stabilized dish antennas were big, heavy and expensive, and their analog signaling didn’t provide much in the way of bandwidth.
Then the digital revolution transformed satcom just as it did computers and phones. Satcom antennas became smaller, digital signaling faster, satellites got bigger and more sophisticated, and the users got access to higher data rates. Competitors to Inmarsat emerged, some with their own satellite constellations and some that rented space on commercial satellites.
The result today is a much more complex marketplace of satcom products for a variety of vessel and fleet needs.
Inmarsat started out as a nonprofit, intergovernmental organization in 1979. By the 1990s the expansion of technology and the emergence of commercial rivals led to the privatization of the organization as a British company located in London.
Inmarsat has always based its products on big geosynchronous satellites, and the same is true today. In the late 1990s Inmarsat launched its third-generation satellites, the I-3 line. These were the first to use not only global beams that covered an entire hemisphere, but also smaller beams called spot beams that could be aimed at specific high-traffic areas.
In 2005, Inmarsat began launching its fourth generation of satellites, the I-4s, which had higher power and more spot beams. The I-4s were also equipped for true digital service, using packet-switched Internet Protocol (IP) signaling. Inmarsat called the marine flavor of this service FleetBroadband. And while the data capability is slow by land-based standards, for marine applications, FleetBroadband’s 432 kilobits per second (Kbps) offered a true window onto broadband at sea.
The stabilized dish inside a KVH Tracphone V7 IP mini-VSAT antenna unit.
The FleetBroadband service (which operates on L-band frequencies, 800 to 2,150 MHz) was broken down into differently priced products based on data rate. Though Inmarsat is in the process of transitioning to the latest generation of satellites, the I-5 models, the company still offers three versions of FleetBroadband based on price and the size of the vessel’s antenna. The lowest level is FB150, which provides up to 150 Kbps data; FB250 is capable of 284 Kbps data throughput, and the high-end FB500 can do 432 Kbps data. Since these services run in IP, the data stream can be transformed into a variety of products for the end user: telephony, email, short messaging service (SMS), file transfer protocol (FTP), etc.
For users who want a hand-held product, Inmarsat also offers a satphone service called the IsatPhone 2 for voice telephony and low-speed data.
Inmarsat’s latest I-5 satellites have 89 Ka-band spot beams generated by two transmit and two receive apertures. They also are equipped with six steerable spot beams to adjust coverage based on traffic needs. The I-5 satellites are coming on line now (I-5 satellites were launched in December 2013, February 2015 and August 2015, with one more set to launch on a SpaceX Falcon rocket at a yet unspecified date in 2016). These more powerful and capable satellites allow Inmarsat to offer a new digital service called GlobalXpress. This is a nearly worldwide, high-speed Ka-band broadband service designed to serve a variety of customers in aviation, oil and gas operations, government, military, and, of course, maritime industries. The maritime service is called Fleet Xpress, and it promises to provide users with continuous broadband connectivity over most of the world (since Inmarsat uses geosynchronous satellites sitting over the Earth’s equator, high-latitude areas experience weak signals and polar areas get no signal).
In addition to the high data rates of Fleet Xpress, Inmarsat also has begun offering a lower bandwidth service called Fleet One, which provides 100 Kbps and is intended for smaller vessels with less need for a high-end solution.
Like Inmarsat, another satcom service, Iridium Communications, also can boast of having a proprietary constellation of satellites. But unlike Inmarsat, which covers most of the Earth with a handful of geosynchronous spacecraft 23,000 miles above the equator, Iridium uses a swarm of 66 satellites in low Earth orbit (LEO) roughly 485 miles up. The advantage of this approach is that the signals don’t have to travel so far and signal strength can be lower, meaning that a stabilized dish antenna is not required as it is with Inmarsat services (other than text-based Inmarsat C, which does not require a stabilized antenna). This makes sense because Iridium was originally conceived as a hand-held satphone service, providing telephony to those areas lacking cellphone coverage. While smaller and less powerful communications gear is required to use Iridium, the drawback is a lower top-level data rate than the Inmarsat services.
Probably the most intriguing aspect of the Iridium satellite constellation, and a feature that was considered a technological tour de force when it was introduced in the 1990s, is the ability for the L-band Iridium satellites to “crosslink” or pass signal traffic between them. Most satellites are little more than “bent pipes.” A signal goes up to the satellite from the Earth’s surface and when it is received the satellite immediately retransmits it. For the message to get to its destination, however, a land station must be in range of the satellite’s signals. Iridium gets around this problem by relaying signals from satellite to satellite until the message packets reach a satellite that is in view of a land station. Then the message is sent to the ground. This feature is what makes Iridium a truly global network, providing coverage at high latitudes and at the poles where geosynchronous-based systems can’t.
As the focus of satellite communications moved from voice calls toward heavier data usage, Iridium introduced a broadband voice and data service called OpenPort — now called Pilot — that uses a domed antenna and various transceiver options. Unlike the stabilized dish needed for sending and receiving geosynchronous satellite signals, the Pilot antenna is unstabilized, reducing its cost. The Pilot service can provide broadband voice and data up to 134 Kbps.
Some vessel owners choose a VSAT solution. For example, the car carrier Sepang Express, above, is equipped with a KVH mini-VSAT V7 IP antenna. This level of satcom service provides a vessel with 3 Mbps download and 512 Kbps upload connectivity.
The current constellation of Iridium satellites was scheduled to be replaced by 66 Iridium NEXT satellites (plus six in-orbit spares) in 2015. Delays have pushed back the launch dates of the NEXT constellation to this year. The NEXT satellites will broadcast on both L band and Ka band and have better data capability than the original design, allowing for data rates up to 1.5 megabits per second (Mbps) on L band and 8 Mbps on Ka band.
Another satcom provider with its own constellation of satellites is Globalstar. Like Iridium it uses spacecraft in LEOs, so a stabilized antenna is not needed. Unlike Iridium, Globalstar satellites don’t have the capability to relay signals, so Globalstar coverage is limited to those areas within view of an earth station. Globalstar focuses its service more toward telephony users than Iridium and doesn’t have a product comparable to Iridium’s Pilot. Globalstar also offers a tracking and emergency signaling service called SPOT. It is not a full-featured communications service, however, intended primarily for search and rescue.
Finally the most wide-open area of satcom is the realm of the very small aperture terminal (VSAT) and the various companies providing hardware and/or air time and data packages to service it. VSATs are satellite terminals generally less than 3.8 meters (12.5 feet) in diameter. Unlike the integrated systems of Inmarsat, Iridium and Globalstar, which own the satellites and sell the service contracts and air time/data packages along with the antennas and associated end-user gear, the VSAT world is more specialized. It is broken up into satellite hardware companies, firms that sell air time and companies that sell end-user antennas. Some VSAT companies like KVH sell both air time/data packages and end-user antennas.
The VSAT world has big satellite communications companies (such as Intelsat, Telenor, Eutelsat, JSAT, NewSat, etc.) that launch and operate large geostationary satellites. These communications satellites have become ever larger and more powerful with the capability for multiple spot beams in the Ku (11 to 17 GHz) and Ka (18 to 31 GHz) bands. One company, ViaSat, for example, later this year will launch the most powerful communications satellite yet. Called ViaSat 2, it will have several hundred spot beams and the capacity for handling 350 gigabits per second (Gbps) of traffic. This is more than twice the 140-Gbps capability of the currently operational ViaSat 1.
The large satellite owners lease capacity to a wide variety of uses, from direct broadcast TV to direct broadcast radio to maritime communications. There are numerous companies that sell air time/data packages to end users, though there are a variety of ways air time/data packages are split up and resold. While this is a more complicated arrangement then the Inmarsat or Iridium model, it does provide a more wide-open market-based approach to air time/data pricing. Companies such as KVH, Marlink, EMC, Thuraya and NSSLGlobal are active players in the air time/data package market. Then there are firms like Intellian and SeaTel that concentrate on antenna hardware.
A new system designed for providing Internet connections to areas of the world that previously had only low-bandwidth links is O3b Networks, which currently has 12 satellites in middle Earth orbits. O3b also has a business segment providing satcom services to the cruise ship industry.
There are other satcom efforts in the works as well, including Sir Richard Branson’s OneWeb, which aims to provide worldwide Internet access using 648 LEO micro-satellites. OneWeb plans to build as many as 15 satellites per week in its newly announced facility near Kennedy Space Center.