What is a beacon you may ask? Well, in brief terms it is a radio station that transmits all the time on a coordinated frequency. In contrast to this is a station that transmits every now and then and perhaps on different frequencies.
The RFzero beacon examples programs are built over the same framework but are slightly different accommodating the differences in sequence and modulation.
- The CW + carrier example is a very simple program that just transmits CW (call and locator) and carrier
- The International Beacon Project (IBP) example is a multi-beacon and multi-frequency (HF) global cluster that transmits in CW and at four different power levels
- The FT4 + CW + carrier example is a single frequency beacon that transmits FT4 at the start of the minute followed by CW (call and locator) and followed by a carrier
- The FT8 + CW + carrier example is a single frequency beacon that transmits FT8 at the start of the minute followed by CW (call and locator) and followed by a carrier
- The JS8 + CW + carrier example is a single frequency beacon that transmits a JS8 heartbeat message at the start of the minute followed by CW (call and locator) and followed by a carrier
- The JT9 + CW + carrier example is a single frequency beacon that transmits JT9 at the start of even minutes and CW (call and locator) at the start of odd minutes followed by a carrier
- The PI4 + CW + carrier and multiplier examples are single frequency beacons that transmit PI4 at the start of the minute followed by CW (call and locator) and followed by a carrier
- The Syncronized Beacon Project (SBP) example is a multi-beacon and multi-frequency (6 m) global cluster that transmits PI4 at the start of the minute followed by CW (call and locator) followed by a carrier. In the inactive period the beacon may transmit on another frequency
- The WSPR and multiplier examples are single frequency beacons that transmit WSPR at the start of even minutes
But before you decide to put a beacon on the air you should ask yourself if there is a need for one more beacon? Are there other beacons on the same band within normal reach? If so your beacon may not be needed unless it brings something new to the airwaves. However, don’t forget to ask for a coordinated frequency for your beacon either with your national or regional beacon coordinators prior to putting your beacon on the air.
Beacon transmissions have long been used as guides to the presence of HF openings and have contributed significantly to our knowledge of propagation. However, the number of HF beacons is steadily increasing and the amount of spectrum available is under pressure. It is more important than ever that beacon operators are aware of the technical parameters required, the reasons for them and the procedure to be followed to obtain an agreed frequency. This is particularly important in respect of bands with narrow beacon allocations.
It is not the intention of this document to prescribe the exact purpose of any beacon, its power level or the number of beacons in any country. It is also not intended to be applied rigorously to experimental or special purpose beacons. It should, however, apply to the vast majority of HF beacons for propagation monitoring.
The beacon proposal should be agreed within the national society (with consultation with neighboring societies where appropriate) and a provisional frequency chosen. The proposed frequency should be submitted to the IARU regional HF beacon coordinator to check for potential interference problems.
In the interests of spectrum economy, the preferred transmission mode at HF is A1a CW. If F1a is used, the shift should not exceed 250 Hz, with MARK on the nominal frequency and SPACE on the lower. Care must be taken to ensure that the transmission has the lowest possible levels of spurious signals, key clicks and phase noise.
Frequency accuracy and spacing
All beacons should operate within the IARU-designated sub-bands. Additionally, solo beacons should avoid frequencies assigned by the IARU to frequency-sharing networks. Frequencies are currently assigned on an exact kHz (e.g. 28.205.0) or a half kHz (e.g. 28.205.5). (However, if beacon numbers continue to grow, 100 Hz spacing may be introduced). Beacons should normally be capable of operating within +/- 25 Hz of their nominal frequency.
As beacons are often heard at very low signal levels, often among spurious signals, it is important that their message be simple, unambiguous and repeated frequently. It is also necessary to have a short period of carrier for frequency checking and strength measurement purposes, and to make it easy to distinguish the mark frequency where FSK is used.
The message should therefore consist of 5-10 seconds of carrier followed by the call sign and (if required) the grid locator at 10-12 words per minute. Nothing more. No gaps in transmission.
To avoid inefficient use of spectrum and presenting an unduly pessimistic impression of propagation conditions, a minimum power of 10 watts e.r.p. is recommended at HF. Other than this, there are no recommendations as to power or antennas other than suitability for purpose and the need to minimise interference.
Operation should be 24-hour continuous. (This does not preclude beacons that switch to different frequencies or beam headings on a regular basis.)
Beacon operators must try to ensure that the operational parameters of their beacons remains as stable as possible and that non-operational time time is kept to a minimum.
It is important that the operational parameters and status of all beacons be widely known. This information should be sent to the Region 1 HF Beacon Coordinator via the local beacon coordinator or spectrum manager at least once a year or whenever the operational parameters are changed.
VHF and above beacons
The primary purpose of beacons is the checking of propagation conditions, both for every day amateur use and for special propagation research projects. When allocating exclusive segments of a band to beacons regard should be given to:
- Reasonable frequency separation is needed to allow for, for instance, auroral spread;
- Guard bands at the edges of the segment are desirable to prevent de-sensitization of receivers used for beacon projects due to strong local traffic on adjacent frequencies.
As beacons are often heard at very low signal levels, together with spurious signals, it is important the message is simple, unambiguous and repeated frequently. It is also necessary to have a period without information (“carrier”) for frequency checking purposes and signal strength measurement; and also to make it easy to distinguish the frequency when using F1A.
- For a coordinated beacon, the only essential information in the beacon message is the call sign.
The locator or other information is not essential
- The call sign should be sent in plain CW at least once per minute, not exceeding 60 characters per minute
- Beacons should include a period of plain carrier of approximately 20-30 s, sufficient for frequency checking purposes.
- For mixed mode beacons, the MGM mode should start on the even minute, whilst the odd minute includes the plain carrier period. Effort should be made to ensure good timing accuracy of the even/odd minutes.
- It may be helpful to indicate a forthcoming change of mode by a short CW symbol (such as an ‘S’ or ‘X’)
- For beacons that are MGM only (which should only be exceptions to the other recommendations) then the message should be MGM at the start, followed by the CW ID within a minute period.
Operation should be 24 hour continuous.
- If beacons change parameters during the transmission this must be reflected in the message transmitted.
- IARU Region-1 encourages best practice for both timing/frequency accuracy and phase noise to enhance general performance for the benefit of all.
- That development of new modes optimized for beacons are encouraged, which may either enhance DX reception or permit more efficient equipment (and thus lower electricity costs) to enhance sustainability
- That National Societies and IARU-R1 coordinators be kept updated on such developments.