What is a software defined radio (SDR) and why most likely don’t need one?

A software-defined radio (SDR) system is a radio communication system which uses software for the modulation and demodulation of radio signals. Mixers, filters, amplifiers, modulators/demodulators, detectors, etc. are taken care of in software, while the RF analogue to digital conversion (and D to A) side is packed in a no-knobs box.

Practically, affordable SDR radios consist of a personal computer and RF box, as two separate units, where high end transceivers like Flex combine both in one unit.

Ham radio SDR has been around for 20 years. There are numerous advantages of SDR technology which is expected to become the dominant technology in radio communications. But we are not there yet. For a two simple reasons: an average amateur does not need an SDR transceiver – his analogue box is robust, reliable, repairable and easy to use in both home, mobile and portable scenarios. The vast majority of amateurs just want to talk to fellow hams (regardless of mode) and a classic radio with knobs is designed and engineered to provide just that. The second reason is that vast majority of amateurs don’t have sufficient knowledge or patience to learn how to integrate PC with RF box, how to setup and run SDR software and how to take advantage of what SDR really offers. The technical level of knowledge in the ham community is rather low: reading schematic diagrams, identifying components or basic soldering skills are almost non-existent. The same applies to basic computer networking skills, and even basic understanding of PC hardware and software is still a mystery to many. This is just reality and it is how it is.

Over the years, the SDR manufacturers have invested countless hours producing instruction manuals, tutorials, instructional videos trying to make SDR accessible to an average amateur. Yet judging by the Ham Reviews of SDR radios, they have failed miserably. “I will never buy a radio which need a PC to run”, “My experience with my 6600M has been just awful”. Here is some feedback on Sun SDR: “SunSDR the experience has been 1st rate from product ordering, follow up communications, and operating.” however, a few months later the same user changed his mind: “UPDATE: Stay away they have made many an unfulfilled promise. Latest still in beta now some 2 years + V3 software is buggy – 2 Meter FM deviation is HORRIBLE (sic)”.

So who are the happy SDR users? A typical profile: an engineer or a technician with both RF and PC knowledge. Or, any other patient amateur who is willing to invest time to learn how to setup and operate radio. Or literally anyone willing to follow instructions, a person with realistic expectations, excited about SDR performance, willing to push his boundaries.

To them, SDR is not just the future of radio communications but daily enjoyment. DX chasers, QRP contesters, 6m and 2m hard core fanatics, short wave listeners, even DXpeditioners – all of them swear by their favourite SDR box and many of them would never go back to analogue boxes.

My personal encounter with SDR goes back more than 15 years ago when I was involved in an SDR radio project called Genesis Radio. It started as a single 40m band 5W transceiver kit, and over the years evolved to an all band HF 25Watts transceiver. The team consisted of an RF engineer, a software engineer and a production and marketing department – which was my role. We have sold almost a thousand kits and I am proud of my contribution to bringing the affordable SDR kit transceivers to amateurs. Heaps of fun.

The decision to represent SunSDR was a natural one. I like hanging around with people who are smarter than me, and learn from them. SunSDR is a powerful box which offers serious performance and value for money. I am really looking forward to getting back into SDR myself.

Make no mistake: my intention is not to sell you an SDR radio. This is simply impossible. If you are already an SDR user then you know what SDR is all about. SunSDR2DX could be a fantastic upgrade to your shack. If you are curious and willing to learn, then you will call me with a simple ‘send me an invoice’. Otherwise, if you are not interested in SDR – no amount of convincing, discounting or begging would turn you into an SDR buyer. Quite frankly, the last thing I need is a buyer who is unwilling to learn, too impatient to study, read a manual and watch a video; someone who would expect me to set his system; someone who would send endless emails, and then, disappointed, leave negative feedback. For that I have no time. It’s simple as that.