The widespread of the Internet, and the ever increasing demand by end users to be connected, every-time and every-where, is slowly but surely penetrating into the mobile satellite communication (Satcom) world in the Air, Train and Ground platforms, but especially in Marine applications. Moreover, in todays modern digital communication environment, broadband connectivity at low affordable cost is no longer a wish but rather a demand.
The Marine Satcom market has developed faster than the Air and Ground applications because the Trip Duration at sea is typically significantly longer than that of the Air or land trip duration, with the demand for the marine market for this service much greater. In addition, the early implementation of Mobile Satcom solution called for larger antennas that were able to comply with the basic standards and satellite regulations that existed then, applicable only for larger vessels (such as Oil Rigs, Tankers, Ferries, and so on) that are typical for the Marine world.
This market demand and the obvious business opportunity pushes the Mobile Satcom Antenna vendors to develop systems that are smaller in size. These are antennas able to fit onto smaller vessels. This enlarges the potential market to more vessels of smaller and smaller sizes. In the past few years, several small sized Ku-band antennas have become available at relatively low cost, opening a broadband channel to smaller sized vessels that can now enjoy always-on Internet connectivity at reasonable prices.
Nevertheless, the technical design of smaller Ku-band antenna systems is challenging. The need to comply with the regulation requirements of the satellite operators can result in higher operational costs and lower cost/performance ratio. As of this writing, low attention is paid to the importance of type approval of Mobile Satcom Systems; however, as the technology grows and the number of Mobile Satcom Systems increases, the need for type-approval and regulation compliance will become a necessity.
Why is regulation needed?
Geostationary satellites maintain their fixed relative positioning in space by moving along a specific orbit and hold a zero-sum force vector at all time. Geostationary positioning becomes possible at a predefined height of 35,680 km (22,170 mi), a predefined speed of 3.07 km/s (1.91 mi/s), and in an orbit that is directly above (parallel to) the earths equator.
As the demand for communication increases and more and more satellites are being placed in the geostationary orbit, it becomes very crowded in space and the satellites end up being positioned closer and closer to each other. This physical proximity between adjacent satellites currently standing at typical values of around 2 degrees requires transmitting earth stations to limit their EIRP per bandwidth toward the adjacent satellites.
As of today, most satellite regulation requirements are aimed for fixed earth stations VSATs, where there are usually no dimensional restrictions. This is not the case for mobile satcom application where there is a conflict of interest between the need of the market to reduce the size of the antenna and the regulation requirement to avoid adjacent satellite interferences.
| . In addition to the need for formal compliance with the regulation requirements, an antenna with better performance (low side-lobe levels) will be beneficial to the service provider, and in certain cases it will avoid the use of Spread Spectrum technology that uses a much larger bandwidth at higher cost to the service provider. .|
The ability to meet the satellite regulation while keeping the dimension of the systems as small as possible is the main differentiator between todays existing mobile satcom solutions. These differences between solutions are the main reasons as to why some systems are capable of obtaining the Type Approval while others fail. The results relate to the antenna size, the quality of the RF system, and the production repeatability capability of the system.
Also to take into account is the dynamic and tracking performance capabilities, with the provision of Cease Tx function (the ability of the system to stop its own transmission within 100 msec when tracking inaccuracy exceeding 0.5 degrees (as required by the FCC and ETSI).
In addition to the need for formal compliance with the regulation requirements, an antenna with better performance (low side-lobe levels) will be beneficial to the service provider and, in certain cases, it will avoid the use of Spread Spectrum technology that uses a much larger bandwidth at higher cost to the service provider.
The Satcom Regulation Status
The Satellite Communication both for Fixed and Mobile earth stations is governed by a three level spectrum management structure (see Figure 2)...
International Telecommunication Union (ITU) defines and recommend the envelope limitations under which transmissions of ships the aircrafts and trains could be operated with GEO satellites worldwide.
Regional regulatory organizations: ETSI for Europe, FCC for North America, Anatel for Brazil and others, derive their own standards and regulations based on the ITU recommendations.
Satellite operators Primarily concerned about the EIRP/Bandwidth as a function of the offset angle from beam center (EIRP/BW) and, about Cross Polarization Discrimination (XPD) at beam center, which is of practical importance for preventing interference to adjacent satellites and to their own satellites by XPD.
The Various Satellite Regulation Standards
Depending on the Authority (region) and type of Mobile Satcom System (Vessel, Train, Air), a relevant standard should be applied some typical & useful standards inlcude:
- Earth Station Vessels (ESV)
ETSI EN 301 447 V1.1.1. (2007-08)
Harmonized European Standard (Telecommunications series)
Satellite Earth Stations and Systems (SES);
Harmonized EN for satellite Earth Stations on board
Vessels (ESVs) operating in the 4/6 GHz frequency bands
allocated to the Fixed Satellite Service (FSS)
covering essential requirements of article 3.2 of the R&TTE directive
- Earth Station Train (EST)
ETSI EN 302 448 V1.1.1. (2007-12)
Harmonized European Standard (Telecommunications series
Satellite Earth Stations and Systems (SES);
Harmonized EN for tracking Earth Stations on Trains (ESTs)
operating in the 14/12 GHz frequency bands
covering essential requirements
under article 3.2 of the R&TTE directive
Federal Communications Commission FCC 04-286
§ 25.221 Blanket Licensing provisions for Earth Stations on Vessels (ESV) receiving in the 3700-4200 MHz (space-to-Earth) frequency band and transmitting in the 5925-6425 MHz (Earth-to-space) frequency band, operating with Geostation Satellites in the Fixed-Sattelite Service.
Sec. 25.22 Blanket Licensing provisions for EarthStations on Vessels (ESVs) receiving in the 10.95-11.2 GHz (space-to-Earth), 11.45-11.7 GHz (space-to Earth), 11.7-12.2 GHz (space-to-Earth) frequency bands and transmitting in the 14.0-14.5 GHz (Earth-to-space) frequency band, operating with Geostationary Satellites in the Fixed-Satellite Service.
RESOLUTION [COM4/20] (WRC-03)
Provisions relating to earth stations located on board vessels which operates in fixed-satellite service networks in the uplink bands 5925-6425 MHz and 14-14.5 GHz
- EARTH STATION MINIMUM TECHNICAL and OPERATION REQUIREMENTS STANDARD M EESS 502 ISSUE 11-Rev.0
INTELSAT EARTH STATION STANDARDS (IESS)
Document IESS-601 (Rev. 12)
PERFORMANCE CHARACTERISTICS FOR EARTH STATIONS ACCESSING THE INTELSAT SPACE SEGMENT FOR INTERNATIONAL AND DOMESTIC SERVICES NOT COVERED BY OTHER EARTH STATION STANDARDS (6/4, 14/11 and 14/12 GHz)
- ADDENDUM TO RESOLUTION No 364, APRIL, 29TH, 2004 NORMS TO CERTIFICATION AND HOMOLOGATION OF EARTH STATIONS ANTENNAS
In the Mobile Satcom Applications, there is a conflict of interest between the market demand for reduced size antenna and the regulation requirement to avoid adjacent satellite interferences.
The ability to meet the Satellite Regulation while keeping the dimension of the systems as small as possible is the main differentiator between todays existing mobile Satcom solutions/manufacturers.
In addition to the need for formal compliance with the regulation requirements, an antenna with better performance (low side-lobe levels while keeping the cross polarization requirement) will be beneficial to the service provider, and in certain cases it will avoid the use of Spread Spectrum technology that utilizes a much larger bandwidth at higher cost to the service provider.
The future need for Mobile Satcom Regulations is clear and, soon no Mobile Satcom System will be allowed to operate without a clear cut approval from local and regional authorities. Most equipment vendors are already taking into their design consideration the requirements that forcing their systems to operate within the imposed regulatory limitations.
There is a real and immediate need that the Satellite Operators will adapt too their requirements to fit the new huge demand for small/compact Mobile Satcom Systems by updating their Type Approvals requirements.
This update should be only for the On-Axis Gain Envelope (side-lobes). Co-polar and cross-polar EIRP per Bandwidth Densities (limitation of the spectral density interference to adjacent satellites and cross polarization interferences).
About the author
Guy Nayum is the V.P of Satcom Systems and R&D Programs for Orbit Technology. Mr. Naym joined Orbit Technology in 1969. Over the years Mr. Naym has gained a worldwide reputation as a technology pioneer in the field of Antenna Tracking / Stabilized Systems & Mobile Satcom, and was the originator of many technical and patented solutions that added to the technical know-how of the company. He leads several developments that involve the establishment of domestic and International cross-functional consortiums in the field of Mobile Satcom. Recently, he served as one of the leaders in the development/design of the OrSat marine system and led the activities to obtain Eutelsat, Intelsat, Anatel Type Approvals for the OrSat system. Mr. Naym holds a degree in PE Electronics as well as an M.B.A.