[NOTE: This Primer is based on my notes for a series of presentations on the Linux User Net, during May and June of 2019. -KC7MM]
On the path to a software-defined ham shack
Understanding Software Defined Radio — and where it can lead.
I recently moved to a new home, and I'm in the process of setting up my station there. What I want to do is to locate my radios in the garage, where they can run off our solar power system's battery backup, and where there is good access to the outside for running antenna leads and grounding. But the garage isn't a good place to sit and operate — I have space available inside the house that is much more amenable to creature comfort, and that's where I want to be when operating.
To that end, I've been working to develop the idea that the functions of Software Defined Radio – and the equipment that performs them – can be distributed over a computer network. My term for it is DARS: Distributed Amateur Radio Station. I sometimes refer to it as Split Station, since the components can be split between different locations.
I've had to learn a lot about SDR in order to both clarify the concept in my mind and to identify what needs to be done to actually implement it. One thing I discovered is that SDR as it applies to Amateur Radio is a complex and often-subtle subject, and there's no single information source that explains it in its entirety.
This primer, then, is my attempt to lay out the fundamentals of SDR as they apply to Amateur radio operation, and to explore where they could take us. I will cover:
We already use software while operating our stations. How does the computer fit into the ham shack?
The short answer: it is employed to add certain capabilities to our radios. In computer terms, it functions as a peripheral of the radio. The station architecture is centered on radios, and computers connected to them perform additional functions.
Radio equipment manufacturers have long installed microcontrollers in their rigs, for control purposes. Their uses include:
Computers connected via serial lines are widely used for:
For the most part, ham radios have not been designed to work over computer networks. The closest most come is some sort of serial port for connecting to a local PC. However, there are systems that can operate, at least in part, over the Internet.