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Software Defined Radio In Action

The intent of his section is to document my experience with Software Defined Radio (SDR). I run only Linux on my computers, so my use of Software Defined Radio – and my observations about it – will be in that general context. SDR has become my area of strongest interest in Amateur Radio.

USB Devices

I possess SDR devices that connect to a computer via USB.


I have owned three SDR transceivers (described below). My current rig is the SunSDR2 DX from Expert Electronics. For my experience with it and tips for running it on Linux, SEE HERE.

Icom IC-7300

Icom IC-7300. The IC-7300 was my first HF rig. It is a direct-sampling SDR HF transciever. Though a true SDR internally, it's designed to operate pretty much the same as an analog set, controlled with the customary knobs and buttons. The touch-screen interface for the menu system is its primary visual digital distinction. I particularly like the filters, which are extremely adjustable and are automated nicely. I also like the fact that it has a USB port for direct connection to a computer, without having to to use a special adapter or cable. Also, the USB port makes two connections, one of which is a sound card that can be used by the computer for digital mode operation – though I haven't yet tried it.

This is a fine radio, and it has served me well. However, from the viewpoint of working dirctly with SDR itself, it is very limited. That led me to look for equipment that would give me greater opportunity for experimenting with software defined radio.

FlexRadio Flex-6600 and Maestro

In August 2019 I purchased a Flex-6600 and a Maestro Control Console. In contrast to the closed-box character of the IC-7300, Flex has designed a system that operates over a computer network. The 6600 is a direct-conversion SDR transceiver, with a built-in Linux server. The only user control on the box is the power switch; all other control is accomplished through software that cdommunicates with the server via TCP/IP through an Ethernet port.

Their SmartSDR software is a Windows application (there is a version for available for iOS). That's a problem for me, with my Linux-only computers. My solution to that is two-fold. First, I got a Maestro control console to get me on the air immediately. It runs SmartSDR on an embedded tablet with a modified version of Windows CE. Second, I'm setting up a Linux system to run a virtual Windows session, under which I'll try to run the Flex software. I haven't been able to find any evidence that anyone has done this before, so it's possible I'm breaking new ground here. I'll update this page as I gain experience with it.

FlexRadio's client-server architecture has the potential to let me realize my goal of building a Distributed Amateur Radio Station (DARS). The TCP/IP API (Application Programming Interface) used by SmartSDR is fully documented, allowing me to write software to control the system. With that, together with USB ports on the server that can be used to communicate with other devices, I have the potential of creating my own front end (user) network nodes for such things as CW keys and audio, as well as back-end station nodes for antenna switches and rotators and the like. I think this could be a lot of fun.

[ … ]

It's now May of 2021. In the latter part of last year, I decided that the Flex is the wrong system for me. It's a superb radio in every respect and I've enjoyed using it, but through experimentation I have determined that the only way to take advantage of its full functionality is to run the SmartSDR and associated software on a Windows PC. I don't want to have a Windows system, so I need to take another route. I should say that there appears to be no technical barrier to writing my own software that would run the Flex on Linux, and I believe that task falls within my abilities as a programmer. The problem is that it would take far more time and effort than I'm willing to put into it. So, the Flex will have to go.

Expert Electronics SunSDR2 DX

In February 2021, a SunSDR2 DX from Expert Electronics arrived at my door. It's in service as of this writing (May 2021), and so far has been everything I hoped it would be. That said, I still have a lot to learn about it, and many of its capabilities (and possible limitations) remain unexplored.

The process of choosing it was pretty simple. First and most important, the ExpertSDR software that runs it is developed to be cross-platform, running natively on Linux as well as Mac and Windows. Everything I read or heard about Expert's SunSDR2 series was enthusiastically laudable. Looking at the manuals and at YouTube videos, it seemed to me that it would fit very nicely into my DARS (Distributed Amateur Radio Station) scheme – much more so than the Flex. Go HERE to see how it has worked out.

sdrmaster.txt · Last modified: 2021/06/03 21:57 by KC7MM