High Availability Maritime SATCOM Starts on the Ship

By Dr Rowan Gilmore, Chief Executive Officer, EM Solutions

Featured in MilSat Magazine, May 2021

Discerning customers who require broadband communications at sea are completely dependent on satellite communications as it provides the only bearer available anywhere, anytime.

Many would not bear the expense unless the satellite link were resilient and high availability. Redundancy can be improved by using multiple satellite systems, and multiple transmitters, since high power solid-state power amplifiers (SSPAs) are usually the most failure prone component in the link.

Frequency stealth can improve resilience by switching or spreading either the modem output frequency or the RF frequency. Changing to a lower frequency band can also protect against weather effects that cause attenuation of the satellite link at higher frequencies such as Ka-band, in spite of their superior bandwidth and capacity.

More specifically, the shipboard terminal determines one critical part of the reliability equation. Communications availability can be improved when the link budget is optimized by using the highest power transmitters possible, the most sensitive receivers, and steered antennas to maintain maximum antenna gain and achieve the best lock on the satellite.

Terminals such as the EM Solutions maritime Cobra terminal are in demand by the world’s greatest navies as they offer all of these features. With multiple band resiliency in a single package, the Cobra covers both commercial and military Ka-bands, as well as X-band simultaneously [1,2].

The new Cobra Fleet terminal uses a 2 meter antenna and will cover X-band and the entire available Ka-band spectrum on any satellite system.

Even given these features, time-on-satellite is a big contributor to the availability equation: minimizing the time for an on-the-move terminal to acquire or reacquire the satellite is crucial, as is maintaining the link under violent motion conditions. That is achieved in the Cobra through its sophisticated monopulse pointing and tracking system.