|After many years of monitoring beacons and using beacons in propagation studies, I have evolved a clear picture on what I believe constitutes the ideal 28MHz beacon from the listener's perspective. I hope my personal views may prove instructive to those who operate or plan to operate a beacon, or indeed anyone with similar interests.|
Please choose a beacon frequency with care. A slot that sounds clear to you may cause interference or suffer interference in other parts of the world where you want your beacon to be heard. You do want the beacon to be heard don't you?
An internationally agreed ten metre beacon sub band is 28.190 to 28.225, with the portion 28.190-28.199 reserved for regional time share beacons, 28.199-28.201 for worldwide time share beacons, with ordinary continuous service beacons expected to fit between 28.201 and 28.225. (Note: authorities in some countries allocate a different frequency range for beacons). However, the older beacon band of 28.200 to 28.300 is still normally used by beacons, and the actual range currently in use is 28.175 to 28.302. In theory, the official beacon sub band should be clear of other traffic but in practice this is (unfortunately) not so! In any case, frequencies in the beacon sub band are at a premium and it may actually be better to select a frequency between 28.215 and 28.300.
Avoid frequencies occupied by other beacons. Frequencies rounded to 10 or 5 kHz are often poor choices as these are commonly in use by existing beacons (and often by illegal CB transmissions). The best way to ensure you use a frequency that avoids clashes with other beacons is to liaise with Martin G3USF (email@example.com) who is IARU Region 1 HF Beacon Co-ordinator. Although Martin's responsibilities lie in Region 1, I am sure he will be pleased to advise on suitable beacon frequencies anywhere. At the very least, please check current frequency usage from G3USF's Worldwide List of HF Beacons, which includes one of the most complete and up-to-date lists of active 10m beacons.
|Transmissions should be continuous 24 hours a day wherever possible. Beacons are propagation indicators: don't second guess nature and turn off your beacon when you think there is no propagation. We rely on continuous transmission to prove the presence or absence of propagation. Remember, the band is never really 'closed' - even at night someone somewhere may be listening via meteor scatter, aurora, auroral E, troposcatter, or via anomalous ionospheric propagation.
Maximise the chances of someone tuning the band hearing your beacon by ensuring there are NO gaps in transmission. Beacon monitoring by the Six and Ten Reporting Club is instructive (see recent results) - beacons with significant gaps of more than a few seconds in the transmitted message are much less likely to be reported than others running continuously with similar power and in the same area. There are well over 100 beacons active, and at present (November 2000) I regularly hear 60 different beacons in a day. During a monitoring slot, listeners don't have time to wait on a frequency in case yet another beacon in W# is QRV! If amplifier duty cycle is a problem, I would suggest the best strategy is to reduce output power in preference to introducing long gaps in transmission.
|The transmitted message needs careful consideration. Think of the listener and what they want to hear as well as what you want to send.
For all listeners, the most important aspect is identification. The beacon should send the callsign frequently, and this should take precedence over all other message content. If a listener can't tell what the beacon is (and hence where it is) it fails its primary function. Callsign sent every 30 seconds is acceptable, but every 15 seconds is better. The number of times that QSB or QRM has interrupted my reception of beacon callsigns is beyond reckoning - don't make me wait another minute or two for another chance at copying a callsign that might similarly be lost. Chances are I'll use a another (and better) beacon instead.
Long rambling messages about the beacon are of no use to man nor beast. Messages should be succinct and repeated often. Please don't send: -
This is painful! Unfortunately a number of beacons actually transmit this sort of stuff. We know it is a beacon so telling us is wasted. We know the country from the callsign. We can read CW so why not use common CW abbreviations and save time? And avoid repetition within the message - since the message itself is repeated continuously there is always another chance to copy. Much better is: -
Grid (Maidenhead) locators are perfect for providing locations. The v's at the start add nothing. Punctuation is not needed. And one can abbreviate station details further.
This is a reasonable and copyable message with all the information in the first example. However, these days most people have access to sources of information on beacons (internet, radio press, etc.) so it is possible to send simply
In fact that's my ideal message! But I realise this minimalist approach may not satisfy beacon keepers or casual listeners. There may be other information you want to transmit (e.g. solar data), or QSL routes may be important to you. In these cases, please consider the brief snappy message interleaved frequently with your other data. As an example we could therefore have:
de xx#xx/b pwr 10w ant gp [pad]
de xx#xx/b QSL xx#xx at some.email.address. [pad]
The [pad] needs explanation. Its the bit that separates each transmission. [pad] can be nothing at all (no break between message repetitions), a space or gap, a series of dots, dashes or morse characters, or continuous carrier. Whatever is chosen, don't make [pad] too long. More than a few seconds of space is counter productive (see 'timing'). 5 seconds or so of carrier is quite useful for those of us who try to measure signal strength, but longer than that is a waste of power - no information is sent and, worse still, your signal runs the chance of being ignored or mistaken for QRM. [pad] of longer than 5 seconds (if really needed) is best filled with a series of dots, dashes or morse characters. Choose something unique and your beacon can be identified by [pad] alone.
|The beacon station configuration needs some thought. I think the issues here - power output, mode, antenna, etc. - are a little easier to deal with than message content, but they are relevant to how well the transmission works as a beacon.
The ideal is to replicate in a beacon an average amateur signal so that listeners know that audible beacons indicate usable openings. In practice this is rarely achieved. With few exceptions, only the NCDXF chain beacons transmit 100w of RF, which might be considered an average amateur transmission. However, as beacons are fixed in frequency they can be listened for carefully, and even if not fully readable, QRP beacon signals may still provide valuable indication of the presence of openings. Power levels of 5 to 10 watts are most frequently used and provide perfectly acceptable signals. Even milliwatt transmissions can be useful, though these are easily overlooked. Power levels will probably be dictated by design considerations, but obviously the more output power the wider the beacon coverage geographically and the more reliable the reception.
Frequency modulated transmissions have some technical advantages but take up spectrum space. Because of this, amplitude modulated signals may be better. Although there is no reason that speech or data transmissions could not be used in a beacon, CW is preferred for bandwidth and because it is easily received. But CW speed is a tricky one. You want everyone to be able to copy but slow morse lengthens the recycle time (and frequency of repetition of callsign). I guess 15 to 20 wpm is OK as everything gets repeated and there is always another chance to copy for those who find cw difficult.
Antennas should be omni-directional unless the beacon is to test propagation on specific circuits. Verticals of one sort or another are almost universally used. Antenna polarisation is only of importance on tropospheric/groundwave paths, a minor component in the reception coverage of most 28 MHz beacons.
The site chosen for a beacon is usually predetermined, and probably a spot in the clear is all that can be asked for. It is worth noting though that some of the most reliable signals are from beacons on hilltops. As might be expected, your beacon will be more useful if it is in an area of the world without existing beacons and is not just another in your country/state!
Operating life. Beacons that are 'permanent' - i.e. are going to operate for years rather than months or weeks - are most appreciated. Knowing that a beacon is always going to be there increases its usefulness. As an example, I know W3VD will be QRV so I know I can look for this beacon to help identify trans-Atlantic sporadic E openings, or F-layer openings at solar minimum, at times when I may not have heard the beacon for many months. Beacons that come and go at irregular intervals are really not too helpful. Beacons that operate for years on end are a real asset and will attract regular listeners - our thanks to all you dedicated beacon keepers!