Is 30m a Digital Band?

 Couple of days back I had noted a lot of seemingly digital signals on the WARC band from 10.100–10.150 MHz. That is the 30m amateur radio band sanctioned by the World Administrative Radio Conference in early 1980s. My End Fed Half Wave antenna for 40-10m with a 49:1 balun at feed point used to tune in to the 30m band with the built-in automatic antenna tuner of my FT-710 radio. After I reduced the wire length of my EFHW for better mounting, from 20m to 10m, the antenna was converted to a 20-10m antenna. It works well for transmission on 20m and I have been able to work a US station with it on SSB during early morning grey line propagation. As the 10m band has been bad recently, I have not been able to work any stations on 10m with the shortened antenna. Though it does not tune to 30m, I could hear a few SSB stations on the band in unknown languages. After sometime, when I checked, I could see a lot of seemingly digital signals on the waterfall.

I checked again today evening and I could find such seemingly digital signals. This time no SSB signals were heard. There is a brief article on 10 MHz or 30m band on the website of Radio Society of Great Britain. According to that article, it is a very narrow band, and is meant for CW and narrow band digital modes only. Another interesting aspect mentioned is that it is an excellent DX band which normally has propagation to somewhere in the world at anytime of the day or night and at anytime in the sunspot cycle. That is really wonderful and I am hearing such a description for an amateur radio band for the first time. According to them, CW DX and DXpeditions are around 10.106 MHz, QRP activity around 10.116 MHz, IOTA operations on or around 10.115 MHz and digital mode activity above 10.130 MHz. But I had seen seemingly digital signals on lower part of the band as well. As I have no way of decoding them, I will not be sure about the type of signal. A check at DXWATCH.COM told me that the current CY9C St. Paul Island DXpedition is on 10.108 MHz, on CW.

The reason why DX contact is possible round the clock is that attenuation due to D layer of the ionosphere is relatively low all year round. This facilitates use of 30m when other bands like 10m, 12m and 17m are no longer usable. 30m CW Activity Group has a wikidot page which has a lot more information on 30m band. According to that amateur radio is a secondary use which should not cause interference to primary users which are named as Fixed Service. But there are no broadcast stations, mobile land, maritime mobile or aeronautical mobile services allowed on 30m. Many countries have lower power limits on 30m and you won't find 'big gun' SSB stations on 30m. I have heard that SSB is allowed in VK land for 30m. I have not seen any specific power limitation in our National Frequency Allocation Plan 2022.