DJ1YFK's Ham Radio Stuff

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All kinds of things too precious not to share, in short articles. Constantly under construction or destruction.


Fabian KurzHam RadioStuff


Band occupancy observations with the RBN

At the IARU Region 1 conference in Albena, Bulgaria (Sept. 20-27, 2014), the current band plan for the 30m amateur radio band (10.100 MHz to 10.150 MHz) was the subject of several papers by national member societies (NRRL, OeVSV, DARC). Currently the lower 40 kHz of the band is limited to CW operation with a maximum bandwidth of 200 Hz, the top 10 kHz also allow digital modes, limited to 500 Hz bandwidth.

In order to support the notion towards an extended, 20 kHz wide digital mode band, as already defined in the IARU Region 2 bandplan, I performed a band occupancy observation, based on data provided by the Reverse Beacon Network.

Methodology: Reverse beacon network raw data from single days was used to compile a “heat map” style diagram of the band activity over full day. The band was segmented into 50 channels of 1 kHz bandwidth on the frequency scale and 96 slots of 15 minutes on the time scale. The number of RBN spots for each of the 50 * 96 = 4800 slots was counted and plotted, normalized to the number of maximum spots in any slot.

Since not all CW skimmers fully cover the 30m band, two plots were made: One that used raw data from all available skimmers and one that only used the spots from selected skimmers which are known to cover the whole band up to 10.150 kHz. These skimmers were ON5KQ, OH6BG and HB9DCO.

Below four graphs are shown. The first two show the typical band occupancy on a week day (Friday, September 5th, 2014), for the full data set (Figure 1) and the selected skimmers (Figure 2). The second two (Figure 3 and 4 respectively) show the same for a day at a weekend (Saturday, September 6th, 2014).

Figure 1: Activity from all skimmers on a Friday
Figure 2: Like Fig. 1 with selected skimmers (see text)
Figure 3: Activity from all skimmers on a Saturday
Figure 4: Like Figure 3, but only selected skimmers

Conclusion: Morse activity is concentrated in the lower 25 kHz of the 30m band. Despite the very generous assumptions that are made for a part of the band to be occupied (1 kHz channel width, 15 minute slots), there are still enough free frequencies to work CW QSOs at almost any time, even during the weekend, below 10130 kHz. Activity above 10130 kHz is mostly beacons (SK6RUD, DK0WCY and some other "ego beacons", which are not operating in accordance with the band plan).

Band plan: No majority for a change of the band plan could be found at the IARU Region 1 conference in Varna, i.e. the band plan will stay as it is for the coming three years, before this subject can be discussed again at the next IARU Region 1 conference which will take place in Munich in September 2017.

Source code: In order to reproduce the results shown above, the Perl source code used to generate them is available for download. Individual RBN raw data can be obtained in ZIP files for single days on the RBN website.


Added: 27-Sep-2014. Last modified: 27-Sep-2014.


Fabian KurzHam RadioStuff