Marine high-frequency single sideband uses, Part 1Mar 10, 2015
Bluewater sailors need to consider HF-SSB as a serious option for their long-range communications. Although HF-SSB may be a bit esoteric for coastwise sailors, it is well worth taking the time to learn about it, especially since it can also be used for sending email and for receiving weather reports. It should be emphasized, however, that even with all of the electronic advances — such as digital signal processing (DSP), automatic antenna tuners (AAT), digital displays, microprocessors and integrated circuits — HF-SSBs are not exactly plug-n’-play. Although, it must be said that today’s HF-SSB radios are much easier to operate than those of times past.
The operator must be aware of the radio wave propagation technicalities, which deal with atmospherics — subjects such as sun spot cycles, ionosphere layers, maximum usable frequency (MUF), lowest frequency available, sky waves, sky-wave bounce, skip zones, angle of radiation, signal paths, long path, etc., to name just a few. The HF band is represented by frequencies between 3 and 30 megahertz (MHz). Since marine SSB systems include frequencies between 2 and 26 MHz, 2 MHz is actually considered medium frequency (MF). The transmit ranges go from approximately 150 miles at 2 MHZ, up to 7,000 miles or even worldwide at 26 MHZ.
From the above we can conclude that these frequencies cover Sea Area A2 and Sea Area A4 if used for alerting and emergency communications in the Global Maritime Distress and Safety System (GMDSS). Also note that as the transmitted frequency goes up, so does the transmitted range. It should also be stated that the SSB modulation system is at least four times more efficient than conventional AM or FM forms of broadcast, and that when the transmitter and receiver are considered together, SSB signal is 16 times greater than with a conventional AM signal. What this means is that a 1-kW SSB signal will “talk” as far as a 4-kW conventional AM or FM transmitter.
The general factors that affect the long-distance HF communications are as follows:
• Time of day
• Season of year
• Location of own ship
• Distance to station being called
• Power settings of equipment (as a general rule of thumb: if you can hear them, they can hear you!)
• Longer distance = higher frequency
• Shorter distance = lower frequency
• Daytime = higher frequency
• Nighttime = lower frequency.
• Daytime, lower HF: can communicate a few hundred miles, increases at night
• Daytime, long distance: use higher HF
The operator of a marine HF-SSB does not need to pass any tests, unlike ham radio operators; however he does need a Restricted Radiotelephone Operator’s permit, which is good for life. If you are a pilot, you already hold one of these licenses; otherwise go to http://wireless.fcc.gov and fill out and submit FCC Form 605. If your HF-SSB radio is a new install, it will also be necessary to obtain a Ship Station license, which is good for 10 years. Before deciding to go HF-SSB you need to consider the costs, which we quote for new equipment —you may want to purchase used equipment at substantial savings, or be prepared to pay the following for new equipment:
• ICOM IC-M802 HF Marine Transceiver: $1,800.00
• HF Antenna: $350.00
• ICOM AT-140 Antenna Tuner: $500.00
This totals almost $3,000 without considering cabling and professional installation by a NEMA Certified Electronic Technician. If you want to add email capability using SailMail in the future, the price goes up at least another $1,000 for SailMail membership and to procure a SCS PTC-IIIusb PACTOR–III modem, so we are talking around $4,000. However if the money is not a problem, there are many advantages to setting up HF-SSB on board your boat/yacht.
This is enough info for now — PART 2 in the next Web Exclusive will deal with the Icom IC-M802 HF Marine Transceiver, PART 3 will cover the SCS PTC-IIIusb PACTOR-III modem, and PART 4 will deal with SailMail and Winlink, while PART 5 will discuss receiving weather information via the SailMail system!