Slow Speed Email

by Dan Piltch on 11 Jul 2006 Those who have tried sending and receiving email via satellite or SSB know that it can be an exercise in patience. The relatively slow speed of satellite means that it takes a considerable amount of time to send or receive a few email messages that on land would be handled in mere seconds - even on a dial-up modem. The chart below helps explain why this is so by showing the relative speeds of various communication devices.

Relative bandwidth: wider pipes allow more information to be transmitted each second.

Notice that the size of the 'pipe' is measured in bits per second or bps.

This reflects how much information (bits) a computer can pass along a certain communication channel each second.

Consider an email message to be represented by a certain quantity of water - that is, a message with three paragraphs of text might be equivalent to, say, a gallon of water.

Notice that the big, wide cable modem pipe can probably transfer this gallon-sized email with ease in a very short amount of time, while the narrow satellite pipe might take considerably longer to send the same gallon-sized message.

When sending multiple emails and the attachments they may carry, it's easy to see that using a satellite device to transfer a significant quantity of emails is like trying to drain a swimming pool through a drinking straw.

As satellite phones entered the mass market a few years ago, an attempt was made to make the data transfer a less painful experience for users. The early solutions involved automatic compression - every transmission first went through a filter that tried to compress the file or message down to a more manageable size.

Essentially, this is like trying to shrink the amount of water in the pool before sending it through the straw. This works well for some messages, but not others.

An email with plain old text is easy to compress down into a smaller size, but one with a photo attached will not compress as well due to the fact that the photo is likely already in compressed (JPG) format.

Many cruisers were still disappointed with the performance of their email sessions on their sat-phones. Much of this is attributable to the 'chatting' that happens behind the scenes during a typical email exchange. Here's how a typical exchange might look between a PC on a boat and a mail server holding email for delivery:

1. PC: Can anybody tell me where to find my mail server?
2. Address server: Yes, that mail server can be found at this address.
3. PC: Dear Mail Server, I'd like to check my mail, my name is Dan.
4. Mail server: OK, Dan, what's your password?
5. PC: My password is SuperSecret.
6. Mail server: Thanks, Dan. You have 1 message waiting.
7. PC: OK, go ahead and send it to me.
8. Mail server: OK, here's your message.
9. PC: Thanks, can you delete it so I don't have to download it again next time?
10. Mail server: OK, I took care of that for you.
11. PC: OK, thanks for the help. Bye now.
12. Mail server: Good bye.

Though most of these exchanges don't involve large amounts of information, there's a lot of back-and-forth transmissions. Given the delay involved in satellite transmission, this adds up to a significantly longer online experience.

A few clever folks figured out how to condense these exchanges into just a few transmissions, by writing their own software:

1. PC: Dear Mail Server (at pre-arranged address), I'd like to check my mail, my name is Dan, and my password is SuperSecret. Please send me all waiting messages.

2. Mail server: OK, Dan, I've verified your password. You have one message waiting, here it is.

3. PC: OK, got it. OK to delete it now. See you later.

4. Mail server: OK. Message has been deleted. Bye-bye.

By reducing the 12 exchanges above to only 4, considerable time is saved.

These clever folks then added other useful features. Some include the ability to receive only messages and attachments that are under a certain size - 'Send me only messages and attachments that take 5 minutes or less to download.'

Others will automatically forward any large messages to a separate mailbox that you can check when on land.

These clever developers continued with their innovations. Using similar protocols, other features were added such as the ability to fetch a given web page, or send changes to a web site. This is handy for those who wish to keep a log of their journey for their friends and family back home.

Another very useful feature is the ability to select a handful of weather charts for downloading. The selections are made offline and then downloaded during the next connection. These charts are the same as those that are broadcast via weatherfax on SSB airwaves, and many additional charts are also available.

The most feature-rich of these programs is Ocens' WeatherNet - a standalone application that focuses on delivering your choice of over 5,000 weather charts as quickly as possible. Ocens also offers a separate mail program appropriate called Ocens Mail.

UUPlus has its origins in work for non governmental organizations in third world countries looking for ways to reduce their satellite airtime bills. Since then UUPlus has successfully entered the marine market and offers a tremendous variety of features in its software.

MarineNet's FastMail has undergone a few changes in recent years, but still relies on a core of Calypso software - used in the wireless industry before being adapted for marine use. Global Marine Networks offers a robust solution, X-Gate, which is available directly from them or from one of their resellers such as Sea-Tech Systems.

In the end the choice between email (and weather chart download) solutions is just as difficult as many other decisions involving marine technology. Work with a knowledgeable dealer, who's well versed in more than just one solution, or poll other cruisers to find out what works best for them.


http://www.marinecomputer.com


The following standalone solutions will work with any satellite based device or service provider including Iridium, Globalstar, Inmarsat, data capable cell phones, and some will work with Pactor modems via SSB:

MailASail
Ed Wildgoose
United Kingdom
Email: info@mailasail.com
Web: www.mailasail.com

FastMail
MarineNet
418 North Cypress Drive Suite: D
Tequesta, Florida 33469
Telephone: 561-747-5686
Fax: 561-747-9357
Email: service@marinenet.net
Web: www.marinenet.net

Ocens Mail
Ocean and Coastal Environmental Sensing, Inc. (OCENS)
19655 First Avenue South, Suite 202
Seattle, WA 98148
Phone: 800.746.1462
Fax: 206.878.8314
Email: info@ocens.com
Web: www.ocens.com

UUPlus
UUPlus, LLC
P.O. Box 6991
Los Osos, CA 93412
Phone: 1.805.534.1425
Fax: 1.805.534.9502
Email: info@uuplus.com
Web: www.uuplus.com

X-Gate
Global Marine Networks
2668 Jericho Rd.
Maryville TN 37803
Phone: 865-379-8723
Fax: 865-681-5017
Email: info@globalmarinenet.net
Web: www.globalmarinenet.net

X-Gate
Sea-Tech Systems
PO Box 1352, Kemah, TX 77565.
Phone: (800) 444-2581,
Fax: (281) 334-3320
Email: navcom@sea-tech.com
Web: www.sea-tech.com


These solutions are typically offered by a satellite airtime provider as a value added feature for their customers. Some offer compression only, while others offer a more full featured set of options like those found in the stand alone solutions above.

StratosNet 2.0
Stratos Global Corp.
Bethesda, MD and Mount Pearl, Newfoundland, Canada
Phone: 888-766-1313
Fax: 709 748 4300
Email: info@stratosglobal.com
Web: www.stratosglobal.com

Velocity Acceleration
For use with TracNet 2.0
KVH Industries
50 Enterprise Center
Middletown, RI 02842
Phone: 401.847.3327
Fax: 401.849.0045
Email: info@kvh.com
Web: www.kvh.com

SatSpeed
For use with WaveCall
Sea Tel, Inc
4030 Nelson Avenue
Concord, California 94520
Phone: 888.798.7979
Fax: 925.798.7986
Email: seat