Ocean Navigator Communications Newsletter #27

SSB Email: Teaching and Old Radio New Tricks

It was recently pointed out to me that I was remiss in not giving enough due to the oldest form of maritime communication - high frequency (HF) radio. Actually, what I want to focus on this time is a specific subset of HF radio which allows you to send data (and therefore email) over the airwaves. The whole notion of email via HF or single-sideband (SSB) radio sometimes has an aura of mystique about it and that sometimes scares people away from investigating it as a real option.

A few years ago, I decided to poke my head out from my sat-comm oriented den and look further into SSB email. I started out just how most folks do - by seeking the advice of a local "guru". I found Tim Hassson - or more accurately, Tim found me - and I tapped into his reserves of knowledge regarding the topic of SSB email. I learned a lot. And then I hired him.

What I learned is that there's really nothing scary at all about sending email over SSB, and in fact it's getting easier than ever. The basics involve an SSB radio (found on many ocean going boats), an HF-modem, and a computer. On your boat, your computer sends the email out to the modem which converts the computer's message into an audio signal that can be sent over the airwaves. On land somewhere, a service provider hears this audio signal and reverses the procedure by processing the signal through a modem and turning it back into a message which is sent to a computer, and from there out to the Internet for delivery.

While there are a few different types of HF modems on the market, nearly all marine service providers use the Pactor series of modems. These modems were initially developed by Special Communications Systems (SCS) of Hanau, Germany and are still manufacturing the world's supply. The current models are the PTC-IIe ($649) and the PTC-II Pro ($985). For a list of dealers who sell Pactor modems, see http://www.yachtwire.com/PTC_dealer_list3.htm. For more about the Pactor technology itself, see http://www.marinecomputer.com/articles/pactor.html.

Once you have the modem and set up and cabled to your computer and radio, you'll need to sign up with a service provider to communicate with. For folks licensed to use the amateur (ham) bands, Winlink offers free service for non-business communications. Yes, that's right - free! All you need is a ham license. Volunteer ham operators at more than 30 stations around the globe then become availale for you use to send and receive emails. For the more common marine licensee, you'll need to choose from one of five other providers such as SailMail, SeaWave, MarineNet and others. When making your selection, consider the provider's coverage, pricing, and additionl services they might offer. For help, see Tim's excellent chart at http://www.marinecomputer.com/resources/HFEmailChart.pdf for a complete list along with current pricing.

OK, so now you've got the hardware and you've got an account with a service provider. All you need to now is tune in to the provider's frequency, listen for an opening when no one else is transmitting, and essentially just hit the "send" button on your computer. The message then gets sent from the computer to the modem, modulated into an audio signal, and sent to the radio to be transmitted. On the other end, the service provider's antenna will pick up your transmission, demodulate the signal with their modem, and process the message for delivery on their computer. The only "catch" in operation is that a provider may have several stations with several frequencies, and you'll need to figure out which station & frequency will offer the best connection for your current location. Here's where the issue of propagation comes in.

Some innovative providers are offering a form of automatic link establishment (ALE) which takes care of this problem for you. By listening to a beacon signal transmitted on all available stations and frequencies, your software can automatically determine which frequency is currently the strongest candidate for transmission and (perhaps) even tune your radio for you.

In addition to this development, SCS has developed a new transmission method called Pactor-III. By switching to the new Pactor-III mode, you're likely to see your transmission speed increase by 3 or 4 times its current (Pactor-II) speed. Your PTC-IIe or PTC-II Pro modem can be upgraded to support Pactor III for $150 at your local dealer.

Keep in mind that all the hardware discussed above is just a first step. Perhaps the most important thing to consider is that the best investment you can make is in some high quality advice and support. So, have fun with your radio, and . . .

Keep in touch.

- Dan Piltch
dpiltch@MarineComputer.com