About this episode
Foundations of Amateur Radio
Recently I came across a series of strident posts about the injustice associated with a non-amateur service using the 70cm band. Complete with links to discussions, spectrum plots, angst and even incoherent outrage, all related to the notion that whomever "allowed" this user to transmit on this band was clearly incompetent.
Except, that this is probably not the case, or the full story.
So, what's going on and why are people incensed?
This all started at least six years ago. Since then AST SpaceMobile has deployed seven low Earth orbit satellites and used the 70cm band to communicate with them. Although in the trial phase, there's plans for an additional 243 satellites, and there's at least one other company playing in the same space, Atmos Space Cargo.
The outcry from amateurs is around the commercial use of "their" 70cm amateur band. It's an emotional statement, but what is the reality?
Before I dig in, let's set some terms. Radio frequencies are globally coordinated because electromagnetism doesn't care about sovereign borders. This coordination is conducted at the United Nations by a body called the ITU, the International Telecommunications Union. Within that body, amateur radio gets a seat at the table from an organisation called the IARU, the International Amateur Radio Union.
For the purposes of the ITU, the world is divided into three, Region 1, or essentially Europe, Russia and Africa, Region 2, the Americas and Greenland, and Region 3, the rest of the world. There's more to it, for example, Antarctica is split across all three, but for the moment, that really doesn't matter.
Of interest is that the band plan, the agreements that outline which frequencies are set aside for what service, might be defined differently across each of those three regions.
To add complexity, each country can be granted exceptions. I don't know the exact mechanics of how this is achieved, but I can guarantee that there's lots of haggling and foot stomping, diplomatically of course. If you're curious how I come to that observation, just look at the absurd list of exceptions associated with each band plan allocation.
Further complexity is added by the fact that not all allocations occupy the same frequency range. For example, in Region 1, the 2m band for Amateurs exists between 144 and 146 MHz, in Region 2 and 3 it's between 144 and 148 MHz.
Within an allocation there is the concept of shared and exclusive priorities. These determine who "wins" if two stations with a different service are transmitting on the same frequency. Essentially, a secondary user may not interfere with a primary user and a tertiary user may not interfere with either a secondary or a primary user and so on. A primary user can pretty much do what they want, as long as they stay within the allocation and don't interfere with other primary users. As a result, the order in which services are listed, matters. An exclusive al
