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Viasat select ETL to design a custom build solution for NBNs satellite network infrastructure

We are very pleased with the quality of ETL's products and their willingness to provide customised couplers to fit our specific requirements. Thanks to ETL we saved considerable rack space cabling and achieved superior RF performance. We plan to continue working with ETL on future systems.
Keith Dishman, Antenna System Engineer, ViaSat

The Situation

ViaSat Inc. is a US-based communications company that delivers fast, secure communications, internet, and network access to virtually any location for consumers, enterprises and governments. Three years ago, the company was contracted by Australia's
National Broadband Network (NBN), an Australia-wide project to upgrade the existing fixed line phone and internet network infrastructure, including in remote and underserved areas. ViaSat, a world leader in Ka-band satellite systems, provided the ground
infrastructure for the NBN Long Term Satellite Service (LTSS) due to launch in 2016. Once complete, NBN's network of satellite ground stations will feature 24 satellite dishes across ten sites in Australia. The ground stations will be located in Bourke, Wolumna, Broken Hill, Carnarvon, Geraldton , Kalgoorlie , Waroona, Roma, Geeveston, and Ceduna. The antenna couplers posed a particular challenge for ViaSat since the couplers require very specific equipment.

Sat ground station Bourke

The Task

In order to overcome the complexity of the couplers for the antennas, ETL was tasked with developing a custom made solution that would simplify the entire coupler network. The couplers were part of the NBN satellite network infrastructure, which included 20 large 13.5m satellite earth station antennas provided by ViaSat for all 10 sites. ViaSat's system design required multiple L-band directional couplers to be installed in each of 12 transmit and receive signal paths. Each transmit path required four couplers in series, while each receive path required three couplers in series. All of these couplers were to be located in standard 19-inch equipment racks at each antenna location. The first approach considered by ViaSat was to purchase individual couplers, mount them on customised mounting plates within each rack, and then connect them together with short cable assemblies. This approach required significant space within the rack and a lot of individual cable assemblies, making ETL's involvement all the more vital.

The Actions

ETL provided ViaSat with passive components, directional couplers and slope equalisers, and the Enigma series of matrix switches, reducing the complexity of the system by designing a single compact module to contain three couplers in series. The size of the module allowed 12 modules to be mounted together on a single rackmount panel and one of the coupled ports from each module was located on the front of the panel assembly to provide a convenient test point for system operators, eliminating the need to open up the rack for access. Meanwhile, ETL's slope equalizers allowed ViaSat to compensate for the insertion loss over frequency caused by long RF cables between the rack-mounted equipment and the antenna. By increasing the bandwidth of its standard product, ETL was able to match the slope of the cable loss, resulting in a nearly flat frequency response in ViaSat's system.

The Result

ETL's compact module assembly not only saved considerable rack space and cabling, but also provided superior RF performance when compared to the traditional method of using individual components. Furthermore, the slope equalisers used were much more reliable and cost effective than previous active slope equalisers used by ViaSat. The installation and commissioning of all satellite earth stations at the 10 sites in Australia is now complete, with each ground station featuring two ViaSat 13.5 metre
satellite antennas, including RF equipment provided by ETL Systems. Two additional antennas at two of the sites, provided by satellite provider Space Systems Loral, will be used for command and control of NBN satellites. The majority of stations also have on-ground solar farms, designed to offset the power consumption of the facilities. The ViaSat antennas, with superior RF performance thanks to ETL Systems, will start operating when NBN launches its satellites later this year.

"When ViaSat explained the project to us we were confident that we would be able to design an effective solution, thanks to the extensive experience of our in-house R&D team. It is particularly pleasing that our RF equipment has been utilized in such an important infrastructure project that will see people's lives enriched through Internet provision." Andrew Bond, Sales Director, ETL Systems.

Sat ground station Wolumla