Mobility is freedom, and freedom changes everything.
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Mobility is freedom, and freedom changes everything.

Meet a pioneer in modern HAM radio, Marcus Roskosch, DL8MRE

Pioneers are explorers and trailblazers. They bring to life the places, things and possibilities that for the rest of us, aren’t even conceivable. And Marcus Roskosch, DL8MRE, is no different. A developer by trade and pioneer by heart, Marcus has made major contributions to HAM radio mobility. Developing applications like SmartSDR™ for iOS, Electronic Toolbox and Network Toolbox, he’s given operators the freedom to take their radio wherever they go. Learn about a true pioneer of modern HAM radio and his experience creating SmartSDR for iOS in this Q&A with Marcus Roskosch, DL8MRE. 

Q: Tell me briefly about your path as a developer and pioneer. 

A: I was a global CIO of a multibillion dollar international grocery discount chain for 15 years until I retired early at 44 in 2008. Before that, I was head of development of a company now known as Sage™ where I also won a few Software design awards.

My goal for my retirement was to have more time for my family and my hobbies which are electronics, HAM radio and software development. 

I bought my first iPhone® in 2007, right after the iPhone had been introduced. I started developing for it, even before the app store existed. Once the app store was available in 2008, I was able to get my first apps, iCluster® and Electronic Toolbox® on the app store. Steve Jobs also mentioned one of my apps when he introduced the iPad® in 2010. I developed a couple of other apps and received a few more awards like the EMMAs Award™ in 2010, and my Network Toolbox® app was awarded “Best App of the Year” in 2013 by PC Magazine™.

Q: Were there any moments in your life that you recognize as guiding you to where you are today?

A: Yes, there are basically three main moments.

The first moment was meeting Conrad Zuse sometime in the early 80s. He was a German engineer who invented the computer in 1935. It was thrilling talking to him and learning how he invented the computer pretty much by chance. He used to downplay what he did by saying he just put together things that were already there, but today, we can’t imagine a world without the things he invented.

The second moment was in 2007 when I saw Steve Jobs’s introduction of the iPhone. I was not an Apple™ fan at the time but once I saw what he was going to roll out, it was immediately clear to me, this product will be a game changer. Now, it is hard to imagine there were times without smartphones, without having the internet in our pockets.

And finally, in 2015 my HAM fellow Norbert (HAM Radio callsign DJ7JC) called me to help with networking problems, and I got to see his FlexRadio 6700® in action. I was speechless and really overwhelmed. He had three screens running with SmartSDR, monitoring many different frequencies and hunting for most wanted DX calls at the same time. Until then, I never considered buying an SDR and wasn’t aware that SDRs were already that advanced. I decided that day to buy a FlexRadio. Now, all major HAM-Radio manufacturers no longer sell legacy, sole analog Radios anymore. But much like the German (or other) Automakers who understood too late that electric cars are the future and are now far behind Tesla, the other HAM-Radio manufacturers are still far behind FlexRadio.

Q: What attracted you to FlexRadio?

A: The absence of loads of cables, the excellent performance, but mainly, the fact that a FlexRadio is a true software defined radio, which means it receives improvements, upgrades and new features via software updates, and it provides a development API, allowing everybody to get everything out of the radio.

Q: How was FlexRadio’s Development API critical to developing SmartSDR for iOS? 

SmartSDR for iOS would not have been possible without the FlexRadio API, and to my knowledge, there is no other radio providing such an API that allows you to control literally every single part of the radio over the network. So for other radios, it is impossible to write such an app. 

Also, the FlexRadio API is well documented and supported by FlexRadio. 

Q: Tell me about the SmartSDR for iOS application development experience. 

Once I got my FlexRadio in December 2015, I became aware of the FlexRadio API. After a bit of “quick-and-dirty” coding, I came to the conclusion that it was possible to write a full-featured app for the FlexRadio which features almost everything available in the Windows version. Which means that you can operate the radio from an iPhone or iPad without needing a PC, and not just from home but also on the road. That was quite a thrilling thought, so I decided to make it real. 

I’m fortunate enough to be retired and don’t have to work for a living, so I was able to concentrate solely on this project, working night and day on the app. Three months later, the app was ready for testing, and in May of 2016, it was available on the app store. I had a lot of testers, contributors and one main contributor, my neighbor and HAM fellow Norbert, DJ7JC. 

Q: What was the most challenging part of the process?

There is a lot of data coming from the radio to the app, which all has to be processed quickly, almost in real-time. Since the computing power of an iPhone or iPad is not as strong as a PC’s, that was a real challenge. 

Q: What was the most enjoyable part of the creation process?

The first time I got sound out of the app and the first time I got the panadapter running and saw the waterfall.

Q: What has been the major feedback you’ve received about the product?

I am still receiving many “thank yous” for this app. I’ve also received several pictures of people using the app in an airplane, on the road and in their garden. One user wrote “… this is probably the coolest way to use HAM radio remotely.” 

Q: What are you most proud of in regards to SmartSDR for iOS?

The overwhelming positive feedback from users of the app. It’s not about the number of apps sold, which I actually don’t even know because it’s not important to me. If an app receives mainly positive feedback, and is being used often, the developer did a good job and that’s always what I am aiming for. 

As for the tech, I’d say the recent integration of the FT8 mode to the app.

Q: Where do you see SmartSDR for iOS going in the future? What are the possibilities?

Besides continuously implementing suggestions or requests from users, I have a couple of my own ideas that will be added over time but I don’t really want to talk about them until they are available.

The app has a section called “Tools” which is where I add new features like recently introduced FT8 mode.

Q: Finally, what other products have you developed that you’re excited about?

I developed a couple of apps for other platforms like Android and Windows. The two major apps of mine that have achieved a success similar to SmartSDR for iOS, are my Electronic Toolbox app (see and the Network Toolbox app (see 

Category:The Flex Insider
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