Want a new receiver? Alex, 4Z5LV makes a number of reasonably priced Afedri SDR-Net software defined radios. Let’s find out how well they work. 

In this series, I will describe my first impressions with the Afedri SDR-Net software defined radio receiver. Alexander Trushkin, who lives in Ariel on the West Bank, designs and makes these radios. He is an electronics engineer and entrepreneur who moved from Belarus to Israel in 2001. Alex has done a lot of analog and digital research and design to develop medical, entertainment, control and communications devices. You can read all about his radio products on the Afedri SDR web site.

Originally, Alex brought out the SDR-Net in late 2011, followed by a dual channel model in 2013. Both were based on the Texas Instruments AFEDRI8201 Single Channel IF ADC processing chip for AM, FM and HD radios. At first, he engineered the dual channel unit using two stacked single channel receiver boards. In 2015, he did a major redesign, implementing the two-channel coherent receiver on a single board using the newer dual-channel AFE8220 chip. I will talk about the design of these radios and their chips in a later article. Suffice it to say, they follow the modern SDR architecture.

As an aside, the Afedri SDR-Net was the first lower cost SDR to implement Ethernet for data and control. Although these radios are fat-pipe in nature, they provide a lot of data easily on Ethernet, which can run faster than USB.

While researching my earlier article on the current state of affordable dual channel coherent receivers, the Afedri radios caught my attention. The Afedri SDR-Net dual channel receiver is priced at US$359 in a case, less for the bare board. (The single channel model is about US$100 less.) Alex has designed this radio to direct sample 100 kHz to 30 MHz using a 12 bit ADC. My initial impression was that the AFE822x would work similarly to the SDRPlay RSP2, with limited dynamic range and only a low-pass filter on the front end.

But, for a reasonable price, I would get a coherent dual-channel radio. Just right for my experiments with Spatial Interference Filtering Techniques, especially removal of local RFI using phase shifting. So, I took the plunge. AFE822x is by far the lowest cost dual-channel SDR receiver around today.

Afedri SDR-Net – About This Series

In this series, I will describe my very early experiences with the AFE822x. There are some challenges which seem to fall into three areas:

• Connectivity and protocols. For the most part, this radio is not pure plug and play. I have run into some apparent HID (USB) conflicts that cause my PC to freeze once in a while, or in some cases, not load the proper configuration. Understanding how the protocols work is difficult.
• Software compatibility. There are challenges setting up the radio to run smoothly on the various SDR programs that claim to run this radio. Solutions are available, but again not pure plug and play. Unlike some SDR, the Afedri units do not come with dedicated OEM software.
• Gain settings. Similar to other lower cost SDR, you need to fiddle which gain and attenuation settings to avoid overload and spurious artifacts. Usually these settings are not available in your SDR receiving software and require a companion control box, which is complicated.

I will work through these challenges as a first-time user and describe my findings. Having said these things, however, here is the spoiler alert: AFE822x is a GREAT RADIO and a GREAT VALUE which I will recommend based on experience to date. Especially if you want to experiment with diversity reception.

In the meantime, here is a video review of the Afedri SDR-Net single channel unit.