May 9th, 2007 - Satellite Communications |
Below are links to the various sections of this Newsletter. How do long distance cruisers communicate Satellite Systems, how they work Cost & Equipment Comparison Charts Satellite Antenna Manufacturers Helpful Resources Below are Evaluated sites that have important information on all aspects of communications .
Radio Licensing
YachtCom
USCG Navigation Center Radio Rules & regulations
Global Maritime Distress Safety System. Radio Operators guide
International Maritime Organization IMO communication Zones - Area A1 Within range of VHF coast stations with continuous DSC alerting available (about 20-30 miles)
Companies specializing in communications product and setup.
Three Phone rental Companies (an
alternative to owning)
|
Communications News©
Communication possibilities in the modern day offer a variety of options. We are providing newsletters on each, which include, Cellular phones, VHF, SSB, Satellite and Wifi.
How do long distance cruisers communicate Here are a couple of examples of cruisers and the mixture of communications they use. Quote courtesy www.Spinsheet.com magazine of the Chesapeake Bay. Joe Boyle is a round the world cruiser currently cruising a large sailing cat. Joe uses a Fujitsu Life book for navigation, communication (e mail & skype) and entertainment (DVD). For weather he uses Weathernet from www.Ocens.net, via Globalstar phone. He also uses www.sailmail.com for getting e mail on his SSB, but he found it easier to pay a little more and use the sat phone or internet connections. He uses Wifi a lot and found Wifi access in 80% of the harbors and marinas they visited. They run an antenna up a halyard which increases Wifi reception 10 times. They use www.skype.com to call friends Marine Computer has this article which describes various boats and their approach to communications. Boats ranged in size from a Hunter 376 to Swan 56. We first met Nigel MacEwan in 1999, when his onboard laptop computer started having trouble talking to his Inmarsat Mini-M satellite phone. Since then, he and his wife Judy have crossed the Atlantic twice, visiting the British Isles, the Iberian peninsula, Madeira, the Canaries and the Caribbean. Before making the last Atlantic crossing, the MacEwans added an Inmarsat C terminal to his existing mix which included a VHF radio and an SEA single sideband (SSB) radio. Inmarsat-C, or Sat-C, equipment consists of a $3,500 small black box that hooks into the boat’s laptop and provides access to a text based system enabling the reception of free weather in English at least four times a day, as well as sending and receiving email See other boats setups in this article Satellite Systems how they work Satellite communications are the most expensive form of communications. Satellites have three basic orbits around the earth. They are GEO (geosynchronous), MEO (medium Earth orbit) and LEO (low earth orbit). GEO satellites are 22,800 miles above the earth surface, while the MEO are around 8,000 miles and LEO between 200 and 930 miles. A little visualization is required to see that a GEO satellite's beam can cover a much greater portion of the Earths surface (footprint) simply because its much further away. Therefore for worldwide coverage only 5 satellites are needed. The GEO satellites are geostationary because they appear to be stationary in the sky as they mimic the Earths rotation. The GEO satellite are out or reach of the gravitational pull of the earth and so require little power. The problem with the GEO satellites is, for you to send a signal to one you will need a large directionally stable antenna. Being almost 23,00 miles away a very accurate signal is required from the sender. These antenna are too large for smaller boats as they need a stable mounting. MEO and LEO satellites can be accessed with much smaller antenna.
Because of their lower orbit these satellites need to travel around 17,000
MPH to counter gravity. Also because of the lower orbit, many more
satellites are required increasing costs. Iridium for example was named
for the element Iridium whose atomic number is 77 and represents the
original number of satellites in that system. To get a worldwide coverage
they use what they call "store and forward" signals. Because of the
number of satellites you send a signal to the closest one and it stores
the signal and then forwards it on the next satellite and the another and so on until it gets
to satellite which is closest to the party you are trying to contact. The Satellite Systems include INMARSAT The first products for the yacht use was the Mini M telephone. Too small and slow to surf the web but OK for small text based messages Inmarsat-C, is a text only e mail system between 70N and 70S. GMDSS safety distress signal sends out MMSI number lat & lon, course & speed, when the red distress button is pushed.. Priced per character The launch of Fleet 77 from Inmarsat upped offshore data communications. The antenna is 3ft wide and costs in the $24,000 region. The data speed is 64,000 bps which is close to land connections and can be always on. Other Fleet systems are the F55 and F33, both smaller slower than the F77 system.
Iridium mainly aimed at voice communications. Iridium operates 66 LEO satellites and is truly global. Handheld telephones can transmit to this lower orbit, without the need to be stabilized. Iridium operates at 2,400 bps same as mini -M. The department of defense uses Iridium. Iridium Satellite LLC is the only provider of truly global satellite voice and data solutions with complete coverage of the earth (including oceans, airways and Polar Regions). Iridium delivers essential communications services to and from remote areas where no other form of communication is available. Both Iridium and Globalstar have had their fare share of financial and technical issues and this may continues with such an expensive setup. However the ability to call from almost anywhere has to be attractive when on the Ocean or in a third world country. Globalstar provides affordable, dependable high quality satellite voice and data service across North America and to over 120 countries worldwide. Globalstar operates 48 LEO satellites. Handheld telephones can transmit to this lower orbit, without the need to be stabilized. GlobalStar offers crystal clear voice data and data speed of 9,600 bps. GlobalStar Coverage map
OCENS XWeb automatically compresses text
and images, and blocks irrelevant content from downloading, so that you
maximise your airtime minutes. Choose your preferred Web browser, and
communicate with confidence. Skymate has received full type approval by NOOA for its
VMS Vessel Monitoring System which is required for fishing vessels.
Comparison charts comparing various satellite communication systems Because there is no one size fits all. there are many systems and each has its own complexity. Some offer weather, some e mail, some voice and some data only. The spreadsheet from Marine Computer systems and the second from PassageMaker explain what each system costs and capabilities. Marine Computer specialize in Communications. This chart they provide compares all the major systems for global communications, whether they include voice, data only, if they are part of the GMDSS and relative costs.
Passage Maker in their May/June issue did an article on satellite based communications. Click for full comparison chart. This one includes data rates which the Marine Computer does not.
Satellite Antenna Manufacturers using Inmarsat If you opt for Iridium or Globalstar or Skymate they will set you up with antenna. If you opt for the Inmarsat system you will need to buy an antenna from the following list of manufacturers. There are others but this is a pretty good list. Remember these are stabilsed antenna. KVH
Sea
Tel
Thrane
& Thrane
Satellite Training Courses
The Long Range Certificate is the radio qualification for mariners venturing out of VHF range. (valid for vessels up to 300 grt).
GMDSS Long Range Certificate allows you to operate on any maritime MF/HF/VHF frequency/channel and Inmarsat from onboard your Yacht.
Hamble UK based Course.
This book is a complete guide to all forms of communication at sea. It examines the international marine use of cell phones, satellites, amateur radio, and email, cutting through the jargon and sales hype to enable readers to make the right choice for their needs. Comprehensive appendices on radio procedure, tables of radio frequencies and weather broadcast times provide invaluable reference information not available from any other single source.
Developed
by the United States Power Squadrons, the world's largest private,
nonprofit boating organization, Marine Amateur Radio is a complete
guide to the use of ham radio for two-way and network communications among
boats and between boats and shore stations. Briefly, succinctly, and
clearly, this sturdy handbook lays out the advantages of ham radio for
boaters. It explains how to get an operator's license, how to select and
install a receiver and antenna, and how to use the radio for voice and
Morse code communications with other boats and to shore--including
inexpensive telephone patches to home. It also shows readers how to link
up with marine voice nets for weather and safety communication. |
Other Communications newsletter topics VHF VHF and DSC explained
Glossary of Terms Azimuth Bandwidth Baud Footprint SMS Short message service aka text messaging. VOIP AIS IMO MARPA MMSI SAR DSC
|
|
We hope that by showcasing these
products that you will discover something that is of benefit to you. This is
the aim of MyBoatsGear
to bring together manufacturer and
consumer. This is a good sample of gear
you probably didn't see or perhaps explains the products available and what
they do.
Use of this newsletter is not authorized unless
accompanied by the |
For
under $1,000 you get silver box e mail system, which connects to your
computer. and VHF style antenna. Skymate is a "store and forward
system" and charges by character. In addition to text only skymate
offers the ability to send faxes and even voicemail, Weather downloads are
also a benefit. The outgoing message is read by computerized voice and
delivered to a phone number. Skymate is not GMDSS capable. The antenna is
a 38 inch whip. Pricing is per character transmitted, ranging from
a $16/month plan for 8,000 characters sent and received, to $70/month for
50,000 characters. 
logo and or link.