Zanshin I ICOM M801E SSB (Single-Sideband) Radio

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Zanshin I communications The two big radios aboad Zanshin I. The lower one is a Simrad VHF with DSC capability for short-distance and general communication, the upper radio is the SSB (single sideband) radio which, when the conditions are right, could reach around to the other side of the planet. It also has DSC capability.
Zanshin I communications

Communications aboard a ship, particularly on a long passage, are quite important. One needs to receive weather and security reports, monitor and receive distress and other alerts, communicate with other nearby and not quite adjacent vessels and, in the internet age, receive and send e-mails and other digital content.

The standard VHF (Very High Frequency) radio bands use on boats are in the same general frequency bands as what is used in walkie-talkies, aircraft radios and the like. These are transmitted as waves and for that reason are limited in range because the sender and the receiver must be in quasi-optical line-of-sight; basically if they are powerful enough they can reach the horizon but because of the curvature of the earth they cannot be received below the horizon. Having a very high antenna on both the receiving and transmitting ends can increase the range, but it is still pretty well limited to 25 miles.

The frequencies used by the marine SSB radios (which are very close to but not identical with those used by HAM radios) are in a different part of the spectrum and have the advantage that, at certain frequencies, the radio waves can and will bounce off various portions of the upper atmosphere and therefore propagate beyond the horizon. When conditions are right and the transmitter sufficiently strong and correctly installed one can communicate via radio with stations halfway around the world! There is an art to choosing the right frequency, though - conditions change during the course of the day and due to this bouncing around between the surface and the upper atmosphere there often exist areas where the waves don't reach, so-called “dead zones”. If one waits long enough, moves far enough, or chooses a different wavelength the “dead zone” can be shifted around so that it isn't exactly where the receiver is.

The SSB radio is a weighty and power-hungry device. The antenna (usually an isolated portion of a stay) needs to be set up correctly, as does the ground plane of the radio. Unlike FM (frequency modulated) radios, the amount of power used to transmit is amplitude modulated (AM) depends upon the volume you talk with - shouting into the mike will drain more power than merely talking would. Using the SSB for a lot of transmission chews through electrical power and since the transmitters are very finicky when it comes to low voltages it is important to have sufficient battery reserves.

Apart from being able to SSB to chat with your favorite taxi driver in Tokyo, the device can also be coupled with a special radio modem, called a Pactor modem, to allow digital communications. With an appropriate service, one can send and receive e-mails, including special GRIB files for weather information, anywhere at sea regardless of how far offshore the boat is. This can be crucial when traversing oceans and trying to get the best winds or avoid the worst storms and hurricanes/typhoons.

Because of the complexity of the system and potential for really messing up the frequencies that need to be shared with others, one needs to pass an examination and get a LRC (Long Range Certificate) in order to legally operate the radio. In addition, most countries require the radio to have a station license and in order to use a SSB as an approved GMDSS (global maritime distress safety system) device it needs to be registered and receive a unique MMSI (maritime mobile service identity) by the licensing authority for the country in which the ship is registered or under which flag it flies.

While the USA doesn't require licensing the operator of a SSB, the EU now has a requirement that one needs a LRC (Long Range Certificate) or higher license in order to use these frequencies (except in emergencies, naturally). The license isn't too difficult to acquire but it does involve both written and oral examinations.

Downloadable Manuals page - ICOM M801E Manual

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