Modem
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Modem
In order to send and receive email, your computer needs to send and receive a series of ones and zeros. This is called "digital data" and can be used to encode emails, GRIB files, pictures, etc -- basically any piece of data that your computer can handle all comes down to ones and zeros.
Propagating through the atmosphere, travelling through wires, and in many other places, there are electrical waves of various types. These are often "analog signals", for example music or voices that you hear, HF radio signals, satellite radio signals, etc, are all examples of analog signals.
A modem (short for "modulator-demodulator") is any kind of device that converts digital signals to and from analog signals. Modems allow your computer to talk to other computers over long distances. Even when you think that there are digital signals travelling directly to and from your computer (e.g. ethernet, wi-fi), these are in fact all modulated over analog waves travelling through wires or through the air (or through space).
Different types of modems are relevant at sea, but the main ones are:
- Pactor HF radio modems
- Satellite phones
Note that other types of modems exist -- the old style telephone modems, ADSL modems, etc, but these are outside of the scope of this article.
We don't normally refer to a satellite phone as a modem, but in fact all satellite phones are capable of operating as modems for sending digital data as well as making regular voice calls.
HF Pactor Modems
Installation and Setup Details
In order to use a Pactor modem, one of a few different types of HF Radio are required. Generally speaking these are:
- ICOM M710
- ICOM M801E
- ICOM M802
Older ICOM models such as the M600 can sometimes be made to work using a special type of adapter that needs to be patched into the internals of the radio, however last reports were that this adapter was no longer available for the M600.
In addition, the following items are required:
- A computer running Microsoft Windows
- An account with a service provider such as SailMail
- Free software called AirMail3.
Also see the Email at Sea page.
Satellite Modems
Although dedicated satellite modems (data-only devices) are available for use at sea, for the average sailor a satellite phone and connection kit is what is required. For all further details see the satphone page.
Software Modems
We don't normally refer to a piece of software as a modem, but in the case of WINMOR, the software does exactly what a modem does -- converting the ones and zeros inside your computer to and from analog audio signals in your PC mic/speaker jacks. These audio signals are then converted to HF radio signals by the HF Radio itself, just as if you were talking by voice over the radio. For more details on how this works see the WINMOR page.
References
Publications, etc.
Forum Discussions
List links to discussion threads on partnering forums. (see link for requirements).
External Links
Personal Notes
Personal experiences?
