Tagged: freesrp

The FreeSRP SDR is now Seeking Crowd Funding on CrowdSupply

Back in August of 2016 we posted about Lukas Lao Beyer’s work in creating a software defined radio from scratch. His goal was to design something that fit somewhere in between the $300 HackRF and the higher end and more pricey USRP radios. Back then he had completed the design and had a working prototype.

Now the Lukas has put the FreeSRP up on CrowdSupply, a crowd funding website. The FreeSRP is priced at $420 each and the goal is to raise $75,000 in order to begin a manufacturing run of the SDR.  At the time of writing this post, the campaign has been running for a day at is already 8% funded.

The FreeSRP has a tuning range from 70 MHz to 6 GHz, uses a 12-bit ADC with a sampling rate of up to 61.44 MSPS, and has a maximum analog filter bandwidth of 56 MHz. It is a full-duplex radio (can transmit & receive at the same time). The main chip in the unit is the fairly expensive (~$150 USD) AD9364 integrated RF transceiver chip and it also comes with a Xilinx Artix 7 FPGA. Furthermore the hardware and code is entirely open source.

The specs seem somewhat similar to the cheaper LimeSDR, although the main chipset is different as the FreeSRP uses the AD9364 chip and the LimeSDR uses their own LimeMicro LMS7002M chip. The AD9364 is the same chip used in the USRP B200 units. Below is an in-class comparison given on the FreeSRP CrowdSupply page.

FreeSRP Comparisons and PCB Image
FreeSRP Comparisons and PCB Image

Below is the FreeSRP promotional video.

Building a Software Defined Radio from Scratch

Over on his blog Lukas Lao Beyer has uploaded a post that shows his journey with designing and building a software defined radio from scratch. Lukas’ finished SDR design is called the FreeSRP and is based on the Analog Deviced AD9364 transceiver and a Xlinx FPGA.

In his post Lukas describes how he designed the PCB with Altium Designer, routing the traces carefully to ensure the shortest path was used, and to ensure impedance matching was correct. Then after producing the PCB’s with OSH park he writes how he assembled the board by carefully placing the components down by hand and using his reflow oven. This was no easy task due to the manual nature of the operation and the high possibility for undetectable solder problems to arise. Despite the difficulties he found that the SDR powered up as expected.

His next steps were to start work on the FPGA controller design, however he discovered that he had failed to properly route some clock pins on the FPGA. On his third revision of the PCB he was able to fix this. Finally he was able to program the FPGA and get his SDR to work.

Designing an SDR from scratch is no easy task, especially if you have little design experience like Lukas did. However, in the end despite some mistakes he was able to build a working SDR that interfaces with GNU Radio. 

Lukas' FreeSRP SDR.
Lukas’ FreeSRP SDR.