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One more low-cost Zynq SoC dev board, from a reader/spelunker designing SDR cave radios

by Xilinx Employee ‎03-29-2017 12:30 PM - edited ‎03-29-2017 02:45 PM (10,144 Views)

 

A blog post from earlier this week, “Seven low-cost Zynq dev and training boards: a quick review,” prompted an email from Graham Naylor in the UK. Naylor informed me that I’d not mentioned his favorite Zynq-based board, the Trenz TE0722, in that blog post—and then he told me how he’s using the Trenz board (which is really more of a low-cost SOM rather than a training/dev board). During the day, Naylor measures neutron pulses from an ionization chamber using the Zynq-based Red Pitaya open instrumentation platform. (I’ve written many blogs about the Red Pitaya, listed below.) For fun, it appears that Naylor and colleague Pete Allwright design cave radios. If you’ve never heard of a cave radio, you’re in good company because I hadn’t either.

 

Naylor sent me a preprint of an article that will appear in the quarterly BCRA’s Cave Radio & Electronics Group Journal, in the June 2017 issue. (The BCRA is the British Cave Research Association.) Naylor’s and Allwright’s article, titled “Outlining the Architecture of the Nicola 3Z Cave Radio,” discusses the design of a new version of the Nicola 3 rescue radio designed to be used by cave rescue teams for underground communications.

 

The original Nicola 3 radio was based on a Xilinx Spartan-3E FPGA supplied on a module from OHO Elektronik. The FPGA implemented an SDR design for a radio that performs SSB modulation and demodulation using an 87KHz carrier wave. Radio transmission does not occur through the air but through the ground using a couple of electrodes jammed into the earthen floor of the cave. (We’re in a cave, remember?) A little water poured on the earth interface helps improve transmission/reception.

 

 

Nicola 3 Cave Radio in Use.jpg

 

 

Nicola 3 radio on test in Reservoir Hole, Mendip, UK (Photo: Mendip Cave Rescue)

 

 

Xilinx introduced the 90nm Spartan-3E in 2005, so the Nicola cave radio development team has upgraded the Nicola design to the Zynq Z-7010 SoC, which resides on a low-cost Trenz TE0722 SOM. Trenz sells one of these boards for just €64.00 and if you want 500 pieces, the price drops to €48.00.

 

 

 

Trenz TE0722 Zynq SOM.jpg

 

Trenz TE0722 Zynq SOM

 

 

The new radio is called the Nicola 3Z. (I'm guessing "Z" is for "Zynq.") The FPGA fabric in the Zynq SoC implements the SDR functions in the Nicola 3Z radio including the SSB class D modulator, which drives an H-bridge driver for transmission; the receiver’s SSB filter, decimator, and demodulator; and an AGC block implemented on a soft-core Xilinx PicoBlaze 8-bit microcontroller, which is also instantiated in the Zynq SoC’s FPGA. There’s a second PicoBlaze instantiation on chip for housekeeping. That Zynq Z-7010 SoC may be a low-end part, but it’s plenty busy in the Nicola 3Z radio’s design.

 

 

 

Note: For more information about the Zynq-based Red Pitaya open instrumentation platform, see:

 

 

 

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About the Author
  • Be sure to join the Xilinx LinkedIn group to get an update for every new Xcell Daily post! ******************** Steve Leibson is the Director of Strategic Marketing and Business Planning at Xilinx. He started as a system design engineer at HP in the early days of desktop computing, then switched to EDA at Cadnetix, and subsequently became a technical editor for EDN Magazine. He's served as Editor in Chief of EDN Magazine, Embedded Developers Journal, and Microprocessor Report. He has extensive experience in computing, microprocessors, microcontrollers, embedded systems design, design IP, EDA, and programmable logic.