HF Beacons

One of the purposes of the RBN is to allow stations to monitor the strength of their signals. Because of the moment-to-moment changes in propagation that normally accompany HF transmissions, as well as the RBN's unique definition of SNR, it makes sense to see how the RBN reports known stable transmissions over time.

In this post I take the first step, and determine which stations make reasonable candidates for further investigation.

The RBN can quickly tell us which beacons are posted most frequently, simply by counting posts of stations that transmit on a single frequency over a long period. If we look at the period from the RBN's inception in 2009 to the end of 2016 (using, for example, this file), we find the following "top twenty" beacons:

Position	Station	Frequency (kHz)	Number of Posts	Earliest Post	Latest Post
1	I1MMR	7026	244,964	20090308	20161231
2	I1MMR	7027	182,465	20090308	20161231
3	4U1UN	14100	167,360	20140618	20161231
4	AA1K	1821	156,091	20090221	20161231
5	SK6RUD	10133	156,067	20100720	20160421
6	4X6TU	14100	146,961	20110215	20161231
7	DK0WCY	10144	145,174	20100601	20161231
8	W9ZN	7034	144,399	20090225	20161231
9	W0ERE/B	10129	141,262	20100213	20161029
10	W0ERE	10129	135,741	20091105	20161029
11	EW7LO	7008	130,706	20090221	20161231
12	4X6TU	21150	118,790	20110303	20161231
13	IK1HGI/B	7039	111,146	20120516	20161231
14	YV5B	14100	107,564	20131228	20161231
15	DJ6UX	7037	101,942	20121210	20161229
16	DK0WCY	3579	97,002	20111027	20161231
17	DK7JI	7011	96,328	20100112	20161231
18	IK4VFD	7027	94,317	20091130	20161231
19	4X6TU	18110	92,867	20120127	20161231
20	CT1ZQ	7010	91,997	20090301	20161227

Notes:

1. Frequencies are rounded to the nearest kHz;
2. The first two positions are occupied by what is really the same station, which appears to transmit on 7026.5 kHz;
3. Positions 9 and 10 appear to be occupied by a single station, using alternative versions of a single callsign;
4. I am unsure how the U.S. stations in the list can be legal, since the FCC's regulations appear to limit [unattended] HF beacons to a portion of 10m;
5. FCC regulations also appear to disallow the use of the "/B" indicator as used by station number 9, as the B series is allocated to China.
6. It is my memory that the original HF beacons were all located on 28 MHz, so that listeners could be made aware of an opening. It is noticeable that not a single one of the stations on the list above is on 10m: the vast majority are on bands that can reasonably be expected to support some kind of non-local propagation at almost all times (which is probably the very reason that they are posted by the RBN so often -- but one does wonder what the putative purpose of such a beacon is);
7. Of the twenty stations in the list, all but five were still active as of the end of 2016.