Modern Offshore Satcom takes you to the 4th dimension

The need of modern and reliable offshore communication solutions have created a strong evolution of the satellite communication in the maritime sector during the last few years. Many ITC-managers in the offshore business have struggled through the past, just to keep the communication line up and running. In the past, many vessels in the shipping industry have not been incorporated into the company’s network just because if they do, they must be sure to be always on – and not almost always on. Now the scene has changed and there are many good available services out there, but where to find them, what to choose and when to get two dollars back from the dollar invested in equipment and services?

The world of marine satcom services is currently divided into the VSAT (Very Small Aperture Terminals) and the Inmarsat segments. The big difference between them is that VSATs are customer designed and the investment in equipment is higher, but the traffic fees are much lower. Inmarsat has some standard low speed services to offer and the traffic fees are high.

A rule of thumb is if you are connected at sea some 5 to 8 minutes per day, the VSAT solution soon gives you return of investment, depending on the mix of voice and data utilised in the service. Data services are more expensive compared to voice.

VSAT
Present VSAT systems on the market have similar basic design, the central pole, and experience similar issues. One issue is the so-called zenith paradox whilst operating in the tropics during dynamic conditions; another is the need for static balance of each axis for acceptable performance.

A new unique 4 axes stabilised antenna is now entering the market and it is different in many ways. Each axis has guidance & control at the circumference enabling an improved pointing accuracy without the need of balancing each axis.

The patented stabilised antenna control has a heart of fibre optic laser gyros, supported by the tracking device, updating the antenna control unit. This different hierarchy improves the reliability tremendously. For example if the signal for any reason is lost or rapidly decreasing, this new system does not need to be restarted. As soon as the tower, mountain or dark cloud is passed, the system still will be on-line.

The improvements in the link budget enables a higher speed of downloading or uploading data, increased number of telephone channels or reduced power of transmission, customer’s choice.

Interactive reliable communication between Oil & Gas rigs or FPSOs and the office ashore can considerably benefit from this unique technology. Networks running the open standard “Digital Video Broadcasting – Return Channel via Satellite” (DVB-RCS), with a prime target to optimise the use of the spectrum and the bandwidth, are designed to adapt the transmission power on demand, just like in common cell phone networks e.g. GSM.

Oil & Gas rigs, FPSOs, LNGs and mid-size vessels benefit from no external gyros or compass needed.

C2SAT, the Swedish stabilised antenna provider, launches a new, unique different 1.2 m Ku-band VSAT for maritime satellite communication. Question; is different different – or is different better?

The C2SAT patented stabilised antenna is different in many ways. It has no central pole and comprises four stabilised axes for solving the zenith paradox. Why four axes? Space only has three dimensions. During zenith path and during dynamic conditions common systems need to rotate the whole antenna half a revolution back and forth every time the ship rolls. In a region approximately between latitude 30 degrees north and 30 degrees south, vessels, FPSOs, LNGs etc during dynamic conditions will experience following issue each time it rolls. During each roll the satellite will be seen sometimes from above, sometimes from below. To keep the polarisation the whole antenna must be rotated half a revolver. The four axes design solves this problem. Using the additional 4th elevation axis, the antenna just swings back and forth like a pendulum, even in the region around the equator. Each axis has guidance & control at the circumference enabling not only an improved pointing accuracy without the need of balancing each axis, but also keeping the polarisation aligned to minimize loss of signal or speed loss measured in bits per second. Not needing counter weights and balancing is great advantage, saving time during installation and also contributes to the reduced need for maintenance.

The C2SAT? system makes it possible to increase the number of terminals in the off shore network, utilising the same satellite link. Since the traffic fees are based on a maximum bandwidth, it is interesting for every ITC manager in any fleet to carefully examine the C2SAT solution.

One major reason for not installing modern satcom equipment in the maritime industry has been the unpredictable monthly fee and a considerable investment cost. This seems to change rapidly. Better services are now available on flat fee basis and traffic costs for VSAT services are reaching very interesting levels for the customers, reducing time for return of investments.

Some price examples
Inmarsat: A typical 64 kbps voice & data service costs a monthly fee at about $200 and additional $10 per minute using ISDN or $19 per Mega Byte (MB) using Mobile Packet Data Service (MPDS).
Service provider Stratos offers the Fleet 55 service voice at off-peak hours for $2.29 per minute and at peak for $3.29.

VSAT solutions: The most interesting new approach from some VSAT service providers is the flat fee introduction, making it possible to predict the satcom costs much better than before.
Classic 64 kbps phone and data services are available for less than $1 per minute, not including licence fee or rental of equipment. If you choose the flat fee option you can get the 64 kbps service for $2,500 a month for a 3-year subscription and $1,995 a month for a 5-year subscription including lease of equipment.

The Service Provider NSSL has made following comparison:

	VSAT	Inmarsat B	InmarsatF77
1 MB download time	39 seconds	124 seconds	124 seconds
Usage for $59.00	24 hours	8 minutes	9 minutes

From a technical point of view, the most interesting part is the possibility for high frequency VSATs to send several times more data, for the same expense as with low frequency Inmarsat terminals. Attractive VSAT services are provided in so-called Ku-band (10 –15 GHz) compared to L-band services for Inmarsat (1 - 2 GHz) Economically the maritime industry can benefit from further reduced traffic fees.

To get availability to the Ku-band services a high performance stabilised VSAT antenna will be needed, to keep the alignment towards the satellite at sea even during harsh conditions. The higher frequency involved, the better stabilisation will be needed. Many common Ku-band systems have problem to detect and compensate for misalignment of the polarisation. This results in loss in the wanted polarisation and noise disturbance in the opposite polarisation. For this reason C2SAT has chosen to specify performance as tracking accuracy, including the polarisation losses. Specifying pointing accuracy only tells half the story. Including the polarisation issue is more fair, since it focuses on the benefits from the customers’ point of view.

The Swedish company C2SAT communications AB has developed a new generation of stabilised VSAT antennas, making it possible to utilise the bandwidth you actually pay for providing more bits for the buck. A few vital differences between the C2SAT stabilised antenna and the present competitors on the market have been highlighted e.g. the C2SAT patented system is not dependent on gravitation and inertia for the stabilisation.

The C2SAT system has total control of the stabilisation by servomotors holding a firm grip at the circumference on each axis, making the guidance and control superior. The extra ordinary pointing accuracy including keeping the alignment of polarisation, makes it possible to get the bandwidth actually paid for, by maintaining the direction within a 0.1 dB range of the optimal signal peak from the satellite. With other systems, a 3 dB loss due to misalignment is not uncommon. The result is a loss of half the power or half transmission speed. You pay for a 128 kbps speed, but get only 64 kbps. The C2SAT technology further improves the download time and transmitting speed.

The battle between Inmarsat and VSAT has just started, but right now we are standing at the crossroads. Low price terminal and high traffic costs or more expensive stabilised terminals, maybe leased, and low traffic fees with high-speed communication. The last words goes to Fredrik Hånell, President with C2SAT. “You never miss your water until your well runs dry -once they have the C2SAT VSAT onboard, they will never give it up”

C2SAT – The difference between always on, and almost always on!