While most mariners understandably think of an SSB radio as a device for voice communica-tions, the fact is that with the addition of a special modem most SSBs can be transformed into digital communica-tions devices for sending and receiving e-mail via new digital HF modulation techniques like Clover. In addition to giving voyagers the convenience of e-mail, this approach can mean significant savings compared to conventional SSB voice commun-ications that connect to land-based public telephone networks.
There are two companies that have spearheaded this revolution in marine HF communications and are providing e-mail services to mariners: PinOak Digital of Gladstone, N.J., and Globe Wireless of Half Moon Bay, Calif.
A big impetus for these new services is cost. Single-sideband ship-to-shore and shore-to-ship voice calls cost approximately $15 for the first 3-minute minimum. It is $4.98 for every minute thereafter, and there is no discount when one gets stuck on hold or ionospheric static bursts require a message to be repeated several times. Marine voice communications are based on connected minutes of air time, not on the quantity or quality of the message being passed.
“It’s usually a $35 call when I contact the office and give them the details of what I want handled in a one-page letter,” comments John Moore, owner of the 104-foot converted ARB Monsoon. “My single-sideband system has extraordinary range, and I’m not ready to spend $5,000 for a standard C satellite terminal soon,” adds Moore. He also points out that establishing phone calls through foreign public coast stations is more hassle than it is worth. “Half the time, they don’t speak English,” says Moore.
Electronic e-mail over HF SSB radio is one answer for cost-effective data communications to and from small vessels that are already equipped with a marine SSB. Since many blue-water sailors already have an onboard computer for electronic charting and keeping track of vessel inventory, etc., all that is necessary is a radio modem that plugs in between a computer and a marine SSB with digital input jacks.
Digital HF has higher connectivity If you haven’t used marine HF, high-speed digital radio before, you are in for a big surpriseit has a higher connectivity potential than voice transmissions. This is because the total power of the transmitter is concentrated in either two or four tones, instead of being spread over the entire voice bandwidth. In other words, HF digital radio uses only 100 or 200 Hz of bandwidth power instead of the typical 2,500 Hz that voice broadcasts require. As a result of this concentrated power, the user gets something up to 10 times the 100-watt “communications power” of a marine radio. In addition, since this process works in digital mode, computer software exists that can find a signal that a human operator can’t hear and can display the characters on screen. This is called “code gain” and is a new and exciting concept in which users get communications power out of software rather than hardware. Since a vessel at sea only has a fraction of the power available to a shore station, the concentrated power and code gain of digital radio help to even the score and allow for better connections.
In addition to sending and receiving e-mail using these new digital techniques, this same PC software technology can also turn an SSB into a low-cost, store-and-forward telex or fax message system using established simplex telegraphy, over radio (SITOR) channels.
An e-mail modem can cost less than $1,500, including the software, and a double-paragraph (50-word) message to the office could cost less than a few dollars with guaranteed 100% text accuracy.
Federal Communications Commission (FCC) ship station licensing for this capability is a snap. One can update one’s present station license by adding “radio telegraph direct printing” (item 22N on current FCC Form 506) and request a five-digit selective-call number (at item 26). A $45 check to the FCC not only adds digital operation to a ship station license, but also gives one the opportunity to add a new EPIRB, plus adding radar (item 22R). One should make sure to double check that marine SSB (items 22 T and U) has already been added to an existing marine VHF license.
This licensing update is important for Globe Wireless users because they need a selective-call number from the FCC. PinOak Digital’s system, on the other hand, operates in Clover and Pactor 2 (see sidebar on Pactor 2) modes, which do not require a sel-call but rather use the station call sign for linking and identifying. Users of PinOak are members of the PinOak Safe Seas Association, and they can connect with PinOak’s private coast station. They can get on the air immediately after they become a member and receive the system from PinOak.
A restricted operator’s permit filed on FCC form 753 costing an additional $45 will allow one to operate a worldwide marine SSB and digital communications system.
Marine radio digital channels can be prestored in non-erasable memory in those marine SSB transceivers listed in the accompanying sidebar. While channel number designators may appear as the same number for voice channels, the data-only channels are separate from marine voice channels.
Voice channel 401 (kHz)
Data channel 401 (kHz) 4,210.5 receive
Globe Wireless WNU
The data channels are located next to SSB marine voice channels, so your automatic antenna coupler or pretuned whip antenna resonates on these frequencies just as well as on the voice channels.
Who is listening? For data communications with shore stations, there are more than 200 radiotelex shore stations in the world as described in the Admiralty List of Radio Signals. All of these worldwide data stationslike WLO in Mobile, Ala., or British Telecom’s Portishead Radio GKA in the U.K.have been coordinated for international billing arrangements for ships of all nations that wish to connect to any foreign coast station along their route through the use of an international accounting authority code. These reciprocal billing arrangements have been developed primarily to meet the need of merchant shipping fleets, but they are also useful to yachts on offshore voyages. These days, however, most coast stations will also accept payment through a subscriber’s credit card.
With the deregulation of the communications industry becoming a worldwide trend, the ownership of and national interest in data coast stations are constantly changing, and many firms in the U.S. have chosen to integrate high-frequency and VHF voice services into one, including SITOR radiotelex and weather facsimile. Weather facsimile from U.S. government stations is constantly under budget attack, so data coast stations may also offer their own in-house weather systems, such as those provided by PinOak Communications, just in case the government weather facsimile stations ultimately get shut down.
Experienced SSB voice users will be familiar with powerful ATandT radio phone shore stations like KMI in San Francisco, WOO in New Jersey, and WOM in Miami. Stations such as KMI, WOM, and WOO (ATandT) do not carry data traffic but instead offer worldwide interconnects as public coast stations accessible to all mariners in conventional 50-baud radio telex. They all use a code derived from the Baudot code named after the French inventor J.M.E. Baudot (1845 to 1903).
SITOR radiotelex at 50 baud still survives due to its long-time use in maritime communications and its installed base in the merchant shipping fleets of the world. Baudot was also the language of 100-baud telex in the 1970s and to some extent still is. Today, however, the Baudot Code has been replaced by the American Standard Code for Information Interchange (ASCII) format. With 256 characters ASCII is the international language of computers. The same is true in international telex.
Individual public coast radio stations such as WLO (U.S.), Portishead Radio (U.K.), Cape Town Radio (South Africa), and many others, offer SITOR services locally to the maritime users in their particular ocean regions. Globe Wireless, with a central traffic facility near San Francisco, uniquely offers worldwide, multiple-station coverage to mariners of all flags in all ocean regions through a global network of coast stations. Telex and Globe e-mail services are provided by more than 26 ITU-authorized SITOR channels, with remote-control equipment feeding a centralized traffic facility in Half Moon Bay, Calif. Currently, the network of Globe Wireless public coast radio stations includes San Francisco, New Orleans, Chatham (Mass.), Hawaii, Bahrain, Sweden, Newfoundland, and New Zealand. Additional stations are planned for Barbados, South Africa, South America, and East Asia.
“The Globe Wireless network of high-frequency coast radio stations is designed to provide both spatial and frequency-diverse channel capacity, which includes Internet e-mail access to all mariners around the globe,” said Craig McCartney, vice president of marketing for Globe Wireless. “Multiple propagation paths together with automated control of the ship’s existing high-frequency SSB radio system provides transmission quality and link availability not previously obtainable in the difficult high-frequency radio propagation environment. Traffic lists, message traffic, weather, and other services are sent throughout all of our worldwide network of stations, for sailors anywhere in the world. This is truly a global radio network.”
PinOak Communications operates its high-frequency data station in Gladstone N.J. PinOak offers more than 4,000 worldwide weather forecasts, updated each minute in the case of sudden storms, or two to four times a day. For polar ice cap imagery, broadcasts occur as satellite availability permits. PinOak also provides e-mail between members and their home base or office and has just announced the forwarding of e-mail to and from vessels via the Internet and Internet access from vessels through its domain name, PinOak.com.
“PinOak was formed to overcome the difficult problems which the radiotelex industry has faced in adapting to a totally new technology which they weren’t configured for,” said Peter Detwiler, long-time sailor and founder/president of PinOak Digital. “PinOak started a totally new system designed around low-cost, powerful microprocessors and thus can exploit new high-speed modulation techniques that are in a state of constant change.” According to Detwiler, PinOak’s service costs the user 600% less than those charged by common-carrier public coast stations. “Our rates are calculated in the amount of bits transferred, which amounts to 12.1 cents per kilobit,” said Detwiler. “PinOak is a brand-new, highly automated station that aims to succeed by advanced software, low capital costs, and computer automation.”
The digital connection Sending and receiving text-based communications over the maritime airwaves began first as continuous wave (CW, Morse code) before moving to big and bulky radio teletype (RTTY) devices. But the big problem with sending RTTY over the airwaves was lost copy when the receiving station would suffer a fade in reception from the transmitting station. The result was several words or sometimes several lines of text that looked more like alphabet soup than a readable message. The sending RTTY station would have no confirmation of how well the message was received until the distant station replied with a command to send everything over again.
Marine telex communications (SITOR) converts the RTTY five-bit code to a seven-bit code with four mark and three space bits in every character. Shore stations broadcast to ships in the forward error-correction mode (FEC). In this mode, each character is sent twice to allow a smooth flow of data from one station to another should an occasional noise burst cover a character or two. The receiving system self-checks for the four mark and three space ratio. If both duplicate letters are covered with noise, the receiving station will leave a space or show an error message.
Normal message traffic to and from ships is carried out using a synchronous mode of SITOR called automatic repeat request (ARQ). The transmitting station sends blocks of three characters and then listens for the receiving station to acknowledge correct receipt of the characters, based on the 4/3 mark-to-space ratio. (The signals sound like a “chirping” over the data channels.) When radio propagation is troubled with noise bursts, the blocks of three characters are re-sent until the correct ratio is restored. In this mode the system is transmitting only half the time. Given noisy conditions, the throughput goes down to even lower effective data rates as characters need to be re-sent more often.
In the SITOR ARQ mode the bandwidth used is 500 Hz by FCC order, and the maximum data rate is a rather slow 50 bps. For example, it typically requires 30 to 40 minutes to receive a six-page daily Associated Press news report via SITOR. This is always a 12K to 13K file. (The basis for this statement is nearly a decade of the author’s personal experience, as well as the experiences of thousands of others, both commercial and amateur, including a generation of use by Jimmy Dezauche, the founder, owner, and CEO of radio station WLO.) SITOR telex costs about $2.00 a minute and approximately 300 characters can be sent per minute. This works out to be about three cents per word. When ship and shore stations are equipped with the right type of digital modems, they can switch into “overdrive” with a relatively new mode of data transmission called Clover. Both Globe Wireless and PinOak use this exciting new modem technology to greatly increase the data throughput of the 500 Hz radiotelex channels. Instead of the two-tone frequency-shift keying signal used in SITOR, Clover uses four tones. This makes upper- and lower-case ASCII characters possible, as well as a maximum data rate of 750 bps. Globe Wireless uses an adaptation of Clover in its product called Globe e-mail to send up to 600 bps in 400 Hz bandwidth so that emissions stay within the allowed 500 kHz channel. This is an increase of more than a 10 times the data rate over SITOR and allows for the transmission of graphics files.
After first establishing the link in SITOR, the Globe e-mail modem goes into Clover mode, increasing the data rate to the maximum error-free rate sustainable in the channel given propagation conditions. This is done via continuous sampling of the link error rate. Globe Wireless also employs a unique system of frequency scanning and adaptive radio control to determine the best propagation path based on the optimum shore station and frequency used. The radio is under continuous control of a background computer routine that scans all suitable channels, listens for incoming traffic, and automatically processes incoming and outgoing messages. All this happens without the intervention of the shipboard operator.
PinOak doesn’t use SITOR at all, but goes directly to either the Clover or Pactor 2 modulation format. Both systems incorporate sophisticated error-correction techniques, and data compression may be employed to further boost the effective use of the channel for graphics and other large file applications.
Both Globe Wireless and PinOak Digital e-mail only bill users for the number of kilobits that are successfully transferred from ship to shore or shore to ship. This means the user doesn’t have to pay for wasted air time due to propagation or other problems in the system. Globe Wireless charges $19.95 per month, including the first 40 kilobits in the monthly charge, and 69 cents per additional kilobit to low-volume users in its economy plan. The message cost goes down to 49 cents per kilobit for higher-volume users paying $39.95 per month, with 120 kilobits included in the monthly charge. This works out to about two cents per word or less than half what it would cost to send a comparable voice message.
PinOak Communications has a $25 annual membership fee plus an annual subscription to e-mail services of $250. On subscribing one obtains 100 file-transfer units that allow a user to upload or download 100 blocks of 1,000 bytes absolutely free. After that the rate is 12¢ per kilobit.
Equivalents One kilobit = 1,024 bits
= 128 bytes (8 bits/byte)
= 128 characters (1 char./byte)
= 26 words (5 char./word)
Globe Wireless has another way of estimating messaging coststhe average 8 1/2-by-11 page of typewritten text (approximately 300 words) will cost around $9.00. A quick message back to the office made up of 25 words would cost less than $1. And when Clover swings into high speed, that one full page of information could be sent in less than 30 secondsand the longer time needed to send a document when conditions are not so good does not increase the cost to get the message through. If a computer and marine SSB work for three hours to send the full text of a business letter, it will be the same exact rate as if conditions were great and the entire document were sent in less than 30 seconds. This is one of the big advantages of using digital communications from ship to shore and shore to ship compared to time-expensive voice SSB.Another advantage of data communications is that written text messages can be delivered far more efficiently than voice messages. Messages can be written and rewritten to get the meaning correct before connecting to either PinOak or Globe Wireless. Once connected, the message can then be sent with a few keystrokes at any time of day or night. (Even using slower SITOR, one third of a page of text can be sent in less than three minutes, often for less than the minimum voice telephone air time charge.) Users of e-mail don’t waste costly air time saying “Hello,” or “What did you say?” or engaging in similar types of ineffective verbal communication. And when the communication session is finished, both sender and receiver can have a hard-copy record of what was saidoften important in business communications. Also, it is much easier to translate messages in a foreign language when working with hard-copy text. When at sea, text messages are transmitted to and from one’s vessel via strategically located shore stations around the world which are switched into the public telephone system, and then are interconnected to telex, fax, the Internet, or any one of many commercial e-mail systems.
And the time it takes to arrive Public correspondence stations like Globe Wireless and other high-seas public coast stations will take any kind of message and put it into electronic-mail distribution for transmission to the destination address within just a few minutes. If a message needs to go to a fax machine in the U.S. it is forwarded by Globe Wireless at no additional charge. If you want the message read to someone over the telephone, this is will cost $6 or more for voice transcription by an operator. But if the party has an Internet or other e-mail address, there may be no additional land-line charges associated with getting the message through. This is a major benefit when one is halfway around the world and doesn’t want to pay stiff land-line forwarding charges. But keep in mind that other countries throughout the world zealously guard their own for-profit communications systems, and don’t want voyagers using an HF SSB when within their jurisdictional boundaries. It is best to use this type of communication when in international waters.
Both PinOak and Globe Wireless have contracted with Hal Communications of Urbana, Ill.which owns the Clover modem designfor Clover radio modems specifically designed for narrow-band direct-printing marine communications. There are subtle changes in the configuration of the modem between PinOak and Globe Wireless so that the systems can’t read each other’s files, and communications are relatively secure. While an enterprising listener with Clover capabilities might be able to crack the code, most Clover marine calls are relatively confidential. Both PinOak and Globe Wireless market their own Hal modems for approximately $1,500, and the installation is usually accomplished by a marine radio electronics dealer who specializes in onboard integrated marine communications systems.
In other words, this equipment isn’t normally available at local marine discount outlets. It takes a general radio operator’s license (GROL) from the FCC to work on marine transmitters, and special skills are required to configure the radio, modem, computer, and software. On some marine SSB transceivers, it is a plug-and-play affair when the radio is already configured for narrow-band direct printing. On other marine SSB transceivers, a technician must go in and hardwire the modem connection, and it may be up to the operator to manually select the best band and frequency. The more expensive the marine SSB, the more capabilities the radio has in automatically switching the frequencies and bands for best throughput.
Whether a voyager chooses the regional scope of PinOak or the worldwide capabilities of Globe Wireless depends on where he or she plans to cruise. If you are cruising throughout the world and want global connectivity for public correspondence, then you may wish to explore Globe Wireless and its worldwide network of pick-up stations which all feed Globe’s central facility in California.
While the spotlight is getting focused on next-generation satellites to provide ship-to-shore and shore-to-ship communications, HF SSB digital communications with public and private coast stations is at a peak in technology and a major low in expense if one already has a marine SSB station onboard.
In comparison to satellite equipment, which could cost as much as $6,000 for a comparable result, worldwide data communications capabilities might cost only $1,500, giving the voyager an affordable communications rate by staying with high frequency and waiting out the satellite systems until they get a lot more affordable.
Gordon West is a freelance writer, lifetime radio amateur, and radio instructor who lives in San Diego.