Broadband communications anywhere, anytime, anyplace can only be provided by satellite communications. But when communications is mission-critical, how can it be made more assured, resilient, and resistant to hostile or environmental interference?
Recognising that such a requirement existed, the Royal Australian Navy, through Australia’s Capability Technology Demonstration Program, worked with EM Solutions to bring such a capability to fruition.
The solution was a satellite terminal that automatically switches between any of three satellite bands on different satellites, even while on-the-move. Mission-critical communications requires guaranteed antenna gain, satellite access, and clear line of sight regardless of weather. Gain can be controlled by carefully steering the antenna, while the choice of several satellites and multiple bands mitigates against weather effects. Although maritime terminals already exist with either commercial or military Ka-band capability, or with dual X-band and military Ka-band capability, none offer universal on-the-move capability (on land or sea) in a convenient size package, simultaneously operating in both X- and Ka-bands, or with fall back to commercial Ka-band on demand. Such a combination brings the benefits of assured communications whenever a satellite is visible without manual changeover of hardware and was the challenge set for the EM Solutions engineering team.
The team’s approach was to work closely with the customer, represented by the Australian Defence Science and Technology Group (DST) to understand the requirements, and cooperate with several collaboration partners. These included Inmarsat Global Government who provided support during the type approval process, and Intellian, who modified their GX modem and below deck unit to pass signal control information between the Inmarsat Operations Centre and the EM Solutions transmitter equipment and stabilised platform. By re-using the unique “monopulse” beacon tracking system found in EM Solutions’ original military Ka-band Taipan class COTM terminal, the new Cobra class terminal came together rapidly, achieving exceptional pointing accuracy and good broadband communications even under the most rugged motion profiles. The monopulse pointing system proved to be extremely fast and accurate, and equally capable of maintaining the link in rough seas as it does off-road.
However, product development never proceeds in a straight line! Midway into the development journey, the Australian Border Force came to Inmarsat and EM Solutions with an immediate requirement for a dual-band system that operated at both the military and commercial Ka-band frequencies. By adapting the work that had already been completed for the Australian Navy, and using EM Solutions Ka-multiband LNB and BUCs, EM Solutions was able to deliver the first of many terminals to the ABF for testing, less than six months after the order was received! Now type approved by Inmarsat GX and operational on Cape Class ships defending Australia’s coastline, these terminals are providing for the first time broadband services to the crew, capable of utilising either the military or commercial bands – the choice depending on satellite availability and network congestion.
The greatest innovation in the new Cobra X/Ka-multiband terminal is its antenna feed system. Optimised for its electromagnetics, the system generates antenna pointing vectors from both the X-and Ka-band beacons of the WGS satellite, and communicates normally at Ka-band, while supporting simultaneous communications on the satellite’s X-band transponder to protect against rain fade, or fall back to operation on the alternative Inmarsat GX satellite system in the case of congestion. Using a 1m diameter parabolic reflector, the terminal has a footprint of only 0.75m, and can be deployed on a range of vessels, from small patrol boats to large ships. At the same time, re-engineering effort has been applied to reduce cost, top weight, and overall terminal volume consistent with the other operating constraints. The newly developed terminal meets both WGS and Inmarsat specifications.
Compared with older terminals, the benefits of the new Cobra multiband terminal include:
- Fully transportable and operational on-the-move capability with unparalleled satellite tracking capability in three bands across all ranges and types of motion (land, sea, air)
- Support for broadband communications (data rates up to several Mbps) without using excessive satellite transponder resources consumed by a very small terminal
- Fall-back to a fully integrated commercial capacity (with built-in modem) in the event of failure or congestion of the military network
- Network survivability with assured communications in a contested environment
- Rapid and automatic self-healing in the event of rain fade or other link outage by switching satellites or band
- Configurability for a range of platforms to suit either a small or medium vehicle or vessel, with simplified field repair and cost optimisation
- Universal stabilisation to the most severe motion conditions i.e. the terminal can be used either on land or at sea
- All X-band and Ka-band electronics are integrated within the radome in a single RF “can”, avoiding the need for expensive and lossy waveguide runs to external equipment racks, and simplifying maintenance.
EM Solutions prides itself on its technological innovation delivered in record time – the new Cobra X/Ka multi-band terminal serving Australia’s Defence Forces is testament to that!
