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.
Below is the FreeSRP promotional video.
The higher frequency SDR’s all stop at 6GHz. If they went to about 6.5GHz they would capture the market space for the Satcoms C-band uplink range (5.850-6.425 GHz). Then I bet a lot more of these would sell to go with C-band SNG Trucks and Fly-Away news-gathering packages.
Oddly enough the HackRF One has two manually adjustable local oscillators, so it could tune up to 7250 MHz, the signal would be attenuated to nothing, but with enough gain and a front end filter you could maybe pull some signal out.
$ hackrf_transfer
receive -r and receive_wav -w options are mutually exclusive
Usage:
… snip
[-i if_freq_hz] # Intermediate Frequency (IF) in Hz [2150MHz to 2750MHz].
[-o lo_freq_hz] # Front-end Local Oscillator (LO) frequency in Hz [84MHz to 5400MHz].
… snip
LimeSDR is a better deal with two channels at a lower cost and already shipping. There is a big risk with any of these crowdfuning projects that the founders haven’t been through the whole logistics process and it ain’t easy to source parts, get boards fabed, assembled, tested, boxed and shipped. Nothing against FreeSDR but it isn’t an easy process and the majority of projects ship late.
As long as your interest in ~200MHz-3.8GHz the Lime is good, it’s front end filters are optimised for mobile phone frequencies and IoT/WiFi/Blutooth frequencies. The LimeSDR also has both channels tied to be within 61.44MHz because of a shared NCO, so you could argue that it is some ways similar to a one channel device, it is not but it is not a four independent channels device either. The two RX channels are linked and the two TX channels are linked.
There is a similar cheaper option (325MHz-3.8GHz https://www.digikey.com/en/product-highlight/a/analog-devices/adalm-pluto). Yes the Adalm-Pluto is only USB 2.0 but there is a powerful little Zqynq SoC (ARM Cortex-A9 @ 667 MHz) , a FPGA with 28k Logic Cells with 80 DSP Slices. Although the crappiest thing about the Adalm-Pluto is the +/-25ppm clock which downgrades it’s uses a lot, but you could upgrade that with something much much better.
Where any software support? the creator of the project hasn’t released any of the code…. This looks like someone trying to dump a bunch of hardware without having any software support. No thanks, I’ll pass….
Actually, code is on github, and linked from the project’s page: https://www.crowdsupply.com/lukas-lao-beyer/freesrp#software
FreeSRP has only 1 channel, but LimeSDR has 2 channels (and supports MIMO). This is really big difference. Also LimeSDR costs $130 less than FreeSRP.