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Unlicensed talk

Jan 1, 2003

Recently, the Federal Communications Commission (FCC) allocated a group of frequencies to a new class of handheld, limited range, unlicensed radio transceiver. Since it is likely that you already have at least one handheld marine VHF transceiver on board, why should you have any interest in more of the same? The answer is complex and yet very simple: the new Family Radios can do things in the marine environment that are difficult or even illegal to do with the marine VHF radios we now use.

This new class of communications is called Family Radio, and its origins are worth noting. Tandy Corporation, of Radio Shack fame, petitioned the FCC for permission to market low-power-output (0.5 watt) transmitters that would operate, without a license, in the 450 MHz, UHF band. Tandy made the argument that these limited-power transmitters would serve numerous useful communications purposes over distances of a mile or two, without creating the massive congestion that is common in many areas on both the marine VHF and Citizens bands. The prospect that widespread use of these new radios might relieve some of the congestion on the marine VHF band may have played a part in the positive decision of the FCC to authorize the new service. Regardless of how it happened, we now have the freedom to use, without a license, a portion of the radio spectrum previously restricted to licensed users.

The rules for the new service require that the radios have no more than 0.5 watts of radio frequency power output; they must use narrow deviation (±3 KHz) frequency modulation; and they must incorporate a transmission time limiter that prevents the "stuck mike" problem still so prevalent on the marine VHF band.

Family Radios (let's call them FRs) can offer as many as 14 channels and are relatively inexpensivesome models sell for less than $100. Their limited power output, along with energy-saving technology borrowed from laptop computers, give these radios fairly long battery lives. The actual specification for most radios is 30 hours of operation, 5% transmit, 5% receive, and 90% in standby, from three AA-size alkaline batteries. FRs typically weigh about seven ounces.

On the marine VHF band, severe channel congestion is often caused by the volume of traffic and the tendency of people to use full licensed power, 25 watts, for vessel stations (ignoring the rule requiring the use of minimum practical power). In addition, there are numerous older maritime VHF radios in use that lack transmitter time-out circuits and therefore can block a channel for periods of minutes to hours.

The audio squelch used in marine band radios also presents a problem, especially when a handheld radio is used. Any signal on the channel of sufficient strength to open the squelch will be heard. In many areas the radio is seldom quiet. Battery power is also consumed by the need to drive the audio amplifier/speaker. In contrast, the squelch system used in FRs is a continuous tone-coded squelch system (CTC-SS) offering 36 different "codes." Unlike marine VHF radios, for which the ability to hear all other signals can be important from a safety standpoint, the FRs are intended for point-to-point use, allowing a very selective squelch to be used. The squelch on FRs operates by transmitting, along with the voice information, a sub-audible, low-frequency tone. On the high-end FRs, any tone can be assigned to any channel; low-end units are more limited. When a transmission is made, only those receivers set to the same combination of channel number and tone (also called Interference Eliminator Code) will unsquelch. A manual squelch defeat button is provided to allow the monitoring of a channel when the signal is very weak or when you wish to check for activity on the channel before making a transmission. Two transmitters operating on the same channel will interfere. However, as with marine band radios, the "capture effect" of FM will usually prevent a fair amount of interference. With the number of choices of squelch code available, it's likely that two or more FRs, operating on the same channel, will be able to enjoy a virtually private channel most of the time. The low-power output of the FRs will usually limit the effective communication range to about 1.5 to two miles, although, as with any radio transmitter, unusual atmospheric conditions and elevated antenna height can allow communication over much longer distances. Where the use of marine-band VHF radios on shore is technically illegal, the FRs can be used virtually anywhere in the U.S. and in areas outside the country where U.S. rules, or no rules, such as the open sea, prevail. Use in other countries is not allowed, unless those countries specifically permit such use. Using a pair of radios to communicate on or between boats is an obvious application. The use of these radios between the anchor handler on the bow and the person at the helm can be quite appealing, especially when the radio is equipped with a voice actuated (VOX) microphone/earphone. For example, communicating with someone working at the top of the mast can make a real difference in coordination. Or talking to a crewmember belowdecks who is trying to bleed air from a diesel engine's injection system is another neat application. Some of the manufacturers, such as Motorola, offer various combinations of accessory microphones, headsets, VOX capability, and belt, shoulder, and arm holders for the radios. With an FR strapped to your upper arm and a VOX operated headset, communication with the dinghy party is a snap. Many of the radios in the market provide night-lighting for the LCD channel display. Some announce, in a rather gravely voice, the selected channel number and squelch.

The uses to which the FRs can be put are virtually endless. This type of communications system could be a good investment for a voyaging vessel.


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