European Space Agency

JANUS Bi-Band Maritime Antenna System

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Objectives

JANUS Bi-Band Maritime Antenna System is based on a reflector antenna terminal able to operate in Tx/Rx Ku commercial band and in Tx/Rx Ka commercial band (not simultaneously). It makes use of an antenna aperture diameter of around 85 cm achieving high Tx and Rx antenna performances in the operative frequencies. The terminal specification is aimed to approach with a suitable cost effective mechanical design taking into account the maritime environmental requirements maintaining tracking performance in line with the existing COTS antenna solution.

JANUS Phase 1 study is aimed to verify a well set of needs and a baseline design for the antenna system that TeS intend to offer to the market of broad band satellite communications services and that shall be able to operate either in Ka- or in Ku-band according to user and service operators agreement.

The target clients of JANUS are mainly both commercial and leisure medium vessels even though it is feasible and desirable to also offer JANUS to the larger ships market. The maritime reference scenario and user requirement as well as the antenna terminal specification have been identified. In the first study phase the aim was also to define a strategy for the safe development of all innovative elements composing JANUS. The objective is to define the terminal specification and the baseline design to develop new technologies for a Ku-and Ka-Band cost-effective satcom system.


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Challenges

  

Benefits

Starting from the results consolidated at the end of Phase 1, the aim is to design, develop and test a prototype of bi-band maritime antenna system with the main outcome to manufacture a prototype having a Technology Readiness Level (TRL) equal to 5.

Features

JANUS Bi-band Maritime Antenna Architecture is composed by the following sub-systems:

  • Antenna Sub-system
  • RF Front-End Sub-system
  • Tracking and Stabilization Sub-system
  • Positioning Sub-system
  • Monitor and Control Sub-system

Figure 2: JANUS Bi-band Maritime Antenna Block diagram

The Antenna is able to transmit and receive signals in Ku-band with linear polarization (H and V) and signals in Ka-band with circular polarization (LHCP and RHCP). The main RF Front-End components are:

  • A Ku-band BUC and a Ku-band LNB (or a Ku-band TRX);
  • A Ka-band BUC and a Ka-band LNB (or a Ku-band TRX);
  • A filtering section;
  • A polarization realignment system for linear polarization, and a polarization switching system for circular polarization.

The Tracking and Stabilization is the sub-system devoted for the Positioning sub-system command and control in order to point the Antenna sub-system towards the satellite direction, taking into account the vessel attitude and the movements.

 

The sub-system integrates also the sensors (GPS, IMU, Encoders) necessary to know the position and the attitude of the terminal. The Positioning Sub-system will be able to:

  • Receive the commands from the Tracking and Stabilization Sub-system;
  • Perform the antenna and RF Front End rotations to maintain the tracking with the satellite signal;
  • Perform the switch from Ku-band to Ka-band and vice versa.

The Monitor and Control Sub-system is in charge of monitoring the status of the equipments and to configure the antenna operational modes and to set up the antenna pointing and satellite tracking. Figure below shows the proposed solution for the M&C S/S in terms of interfaces and functionalities provided.

Figure 3: Monitor and Control S/S block diagram


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M&C S/S communicates with the ACU in order to receive telemetries and to send telecommands for the antenna configuration (operational modes, pointing, tracking, etc.). The protocol utilized for the data exchange is a light and efficient proprietary protocol based on UDP. M&C S/S provides end users with a dedicated GUI to easily access the main functionalities of the system (e.g. display the information on the status of the satellite link, display information about the antenna pointing and ship position, etc.).

The Graphical interface is a standard web application and thus accessible by means of a standard internet browser. The M&C S/S is able to interface with the vessel gyrocompass (if available) in order to receive the ship yaw data. Protocol selected for this communication link is the NMEA 0183, a standard specification for communication between marine electronic devices. An SMNP server is included in the architecture of the sub-system in order to allow a remote management and the monitoring of the antenna system.

Plan

Completed.

Current status

Completed. Final Review.

Contacts

Status date

Tuesday, August 20, 2013 - 11:15