Radio Propagation Beacons (What’s their purpose?)

Many of us of the VHF/UHF/Microwave Ham Radio Community have use beacons to check for band openings and to where the band might be open. More so on the 6M band that any other. We hear the word Beacon bandied about but what is being talked about? What is a beacon? What is the purpose of a beacon? What is essential in a beacon message? What is the protocol? What are the manners and ethics involved?

As many of you know there is no worldwide beacon coordination, and there probably shouldn’t be. A look at the infighting of the various repeater groups involving coordination should summon us to avoid coordination of beacons like the plague.

To enlighten the few and perhaps the many as to just what a beacon is let’s put it in the simplest terms possible. A radio propagation beacon is a radio transmitter; it operates in the FCC designated beacon bands of the Amateur Radio Service. The FCC has also mandated a power limit for beacons of 100 watts output power. A beacon can be a built from scratch transmitter or some ham band transmitter/transceiver that has been modified for beacon service. A beacon is automatically CW keyed by some sort of keyer by which the beacon message is repeated periodically. Beacons are located locally, at ones residence or remotely, on some mountain top or other high place in a community. Beacons are operated off of commercial mains sometimes with battery backup or they can be wind or solar powered on mountain tops.

The purpose of a radio propagation beacon is to indicate to distant stations that a band is open from the beacon location to where it (the beacon) is being heard. Beacons are most prevalent for propagation forecasting in the 10 and 6 meter bands. We do find a few in other HF bands and quite often in the VHF/UHF/Microwave bands. Not only are beacons useful for the indication of band opens but are used for frequency markers, in scientific studies to determine the daily, weekly, monthly or yearly characteristics of a band. Beacons can serve a purpose to many as to equipment performance; such as, is the band dead or is the equipment that is being used to receive the beacon, be it transceivers, transverters, receivers – what have you. Some use a beacon signal for their receiving system optimization; possible but not terribly reliable, more of a sanity check than anything else. This (sanity checking) is generally done with local beacons and in the VHF/UHF/Microwave bands. Propagated beacon signals over distance are time varying which can be heard at an S-9 signal level one minute and a second or so later be an S-1 or gone completely. Test bench signal generators are better pressed into service for system optimization than a time varying ‘off the air’ signal.

 

The message that a beacon conveys needs to be attractive, informative and to the point. Hearing a beacon, what does one want to know about it? First and foremost – WHERE IS IT? Prior to the Maidenhead Conference in New England in the recent past that produced the grid square system, the latitude and longitude of a beacon took some time to be copied and due to the time varying signals parts of the beacon message were lost. Today, a four character grid square designator (e.g. DM79) gives a receiving station a good deal of information as to what part of the country (or world) a band is open, in this case Denver, CO Area. The six character grid square (e.g. DM79ql) narrows the location of the beacon fairly precisely as to just where in the Denver, CO Area. (Google on Maidenhead Grid Squares) dozens of articles, maps and charts of areas of interest will be made available.

 

Besides a grid square designation in a beacon message, a call sign is sent, this due to the FCC requirement that any radio transmission be identified, other than that the call sign if relatively unimportant. What I meant previously by ‘attractive’, I did not mean ‘pretty’, I meant something to get the attention of a receiving station. It has been generally accepted that the sequence “VVV” is going to be followed by a call sign and grid square and that the signal is from a beacon station evidenced by the “/B“ tacked onto the call sign. This seems like a very informative message to be sent from a beacon station for example the beacon message on my 10 GHz beacon station is as follows, “VVV de W6OAL DM79ql (10 second pause and repeat). Nothing more needs to be sent. To review, VVV indicated to a receiving station that they are about to receive a message (generally) from a beacon station. The FCC regulation for identification has been met with the sending “W6OAL”. The location of this call signed station has been identified with the sending of “DM79ql”. Enough said, I don’t have to announce my Mother’s maiden name or how many acres my property entails. As for dits and dashes following a beacon message they may or may not be of any significant importance. Why not just send the message and get off the air so that another beacon station that may be occupying the same of close by frequency can be heard by others? Courtesy, Ethics, Protocol should be paramount considerations of all of us in todays’ crowded and sought after ham bands.

 

Protocol in all its pertinence to the subject at hand is defined by the newest Webster Dictionary as; “a set of rules which governs the format of data and its exchange“. Many things come about as time honored traditions. I’d suggest that most of us that operate radio propagation beacons use the aforementioned protocol in our beacon messages – there are a few exceptions, of course, there is always that “3%”. A respected and used protocol makes scanning the beacon bands so much easier to discern in a moment, propagation characteristics – than listening some drawn out message of “90% no relevance”!

 

Ethics, again from Webster; “a branch of philosophy dealing with what is good and bad and with moral duty and obligation” (I would have also added perpetuity). As relating to the establishment and operation of radio propagation beacons, each of us have our own set of values and moral convictions. In this instance let’s evaluate the amount of power a beacon station could run that might be construed to be ethical. In conversations with other beacon station operators I have found that seldom do they run more than 30 to 50 watts. Especially on the Six Meter Band, a lot of power just is not necessary. Generally when the band is open running 10 watt or a full kilowatt is copy-able Q5 most everywhere in the country to which the band is open. Many times a beacon station is limited in power due to location (i.e. acquiring lots of power by solar or wind on a mountaintop could be rather costly). Such location could entail a lot of hardware, not to mention the cost of that hardware. A small solar or wind powered station running 10 watts or so may be all that is necessary to establish a grid location. The FCC advocates that in all communications one should use only enough power to get the job done. A 100 watt beacon is useless on a dead band. Another consideration is your neighbor. Granted there isn’t really any advantage to two stations in the same city running 100 watt beacon stations on the same band other than ego. In Colorado we have three 6 meter beacons. One in Grand Junction, one in Vail and one in Denver we are separated by considerable distance and a few to many kHz by gentleman’s agreement and good conscience, and this is the way it should be rather than by coordination. Another consideration along the lines of ethics is cleanliness of signal. If only a few kHz separate a couple of semi-local beacon stations it should behoove both operators to keep their signals as clean as possible in an effort to allow a receiving station to be able to copy both.

 

In summary the suggestion is to exercise a little common sense and consideration of others in our beacon station operations. And, realize that beacon operation on the HF bands and 6 meters do not necessarily have to follow the same protocol as the bands above 6 meters. It has been evident for years that beacons in some cases are an ego trip rather than an aid to discerning propagation, still the practice of, “get in” (with a short beacon message), “get out” and leave space for other beacon stations to be heard before the beacon message is repeated, is considered friendly, considerate and ethical.

 

Thanks, Dave – W6OAL/Ø

“Designer, builder and operator” of 5 VHF/UHF beacons in DM79

“Systems Engineer and Integrator” of the Denver (DM79os) 6M beacon