Saturday, November 3, 2012

Inmarsat ISatphone Pro Data Service

ISatPhone Pro
Prior to leaving to cross the Atlantic I purchased an Inmarsat ISatPhone Pro from the Satellite Phone Store for emergency use. I used a prepaid plan and since the more minutes you purchase the longer they last before they expire I bought enough minutes to get a one year duration. After a few months I realized that I was not using up any of my minutes so I started to use the phone occasionally to call my sons.

While in Horta, Azores I installed the drivers for the telephone on my computer. One of the drivers converts the phone into a modem that runs at 2400 bps. This is very slow. Ancient, like me. Consider that the Hayes "Smartmodem" modem of early dial up fame (1987) was a 9600 bps modem. (Technical aside, the Hayes command set "AT" is still used as the standard for most all modems.)

Now consider that the normal setting to render color on your screen is 32 bit color. So we can transmit 75 pixels per second. At 1024 x 768 screen we are dealing with 786432 pixels! The good news is that web sites don't actually transmit all those pixels. They transmit a script that tells your computer how to "render" the page. The script is actually much more compact with one exception - every picture rendered has to be transmitted over the connection.The good news is that the pictures are compressed too so not all the pixels have to be transmitted. However, the end result is still 20 to 40 minutes to render a single web page. How is that for slow?

So what good is a 2400 bps modem on a satellite telephone? What you can do is transmit small amounts of text in a reasonable time. Thus, email works. One can use email to download Grib data (for example from Saildocs.)

Enough theory - how do I actually make it work?  What you need is a telephone number for your phone to call. There are three options:

Option 1 - Connect to Inmarsat

See for step by step instructions. The down side is that you are making a dial up network connection and your computer will do all its uploads and downloads (like automatic updates of your software) while connected. This can lead to quite a lot of minutes.

Option 2 - Use an dedicated (payed) email connection service

I use SPSMail. This is a dedicated service for email.that includes an email address and several options for managing your mail.

Option 3 - Connect to your Internet service provider

Some internet service providers give you a dial telephone number to use "on the road."  Setting up a dial up connection to your provider will also work.

A note: Passage Weather provides a link for "the bandwidth impaired."  Do not confuse "bandwidth impaired" with "bandwidth nonexistent." I have been told that the Passage Weather download takes 30 to 40 minutes on an ISatPhone Pro.

Fair winds and following seas.

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