2017-02-21

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 7034144,399 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.

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