CaribouLite: A 30-6000 MHz 13-bit 4MHz SDR HAT for the Raspberry Pi

Thank you to David for submitting news about his company Caribou Labs' new product called "CaribouLite" which will be a software defined radio HAT for the Raspberry Pi. The product is currently in the pre-launch stage over on Crowd Funding platform CrowdSupply and you can sign up for future updates on the release. David writes:

I'd like to inform you of a product we have developed called CaribouLite board, which is essentially a Raspberry Pi HAT that enabled up to 6GHz SDR capabilities Tx and Rx, and an additional TxRx Sub 1GHz channel.

It uses Microchip's modem AT86RF215 as an I/Q ADC, DAC and frequency conversion is done using Qorvo's RFFC5072 IC. An FPGA (ICE40) is used to stream data packets (I/Q @ 13 bit x2 / sample) back and forth between the Raspberry Pi and the Modem, over an interesting fast interface called SMI.

I think this project brings new ideas to the table and would be interesting to the SDR community.

The use of the SMI interface is an interesting idea and not something we see utilized often as apparently the official documentation is sparse and poor. But David notes how it allows for up to 500Mbit/s of data to be exchanged between the FPGA and Raspberry Pi, although the true throughput depends on the specific Raspberry Pi model used. Regardless the SMI data rate is more than enough for the 120 MBit/s required by the two streams of 13-bit IQ data that the CaribouLite generates.

The campaign also notes that the sample rate is 4 MSPS, with 4 MHz bandwidth, and up to 14 dBm of transmit power is possible. They also note that they are planning to release a wide range of library code that allows for use cases such as wide range spectrum analysis, a signal / protocol generator, an analog / digital DAB+ receiver, an ADS-B receiver and more.

The software and hardware design is also fully open source and available on GitHub.

The CaribouLite SDR HAT mounted on a Raspberry Pi Zero


  1. Clifford Heath

    Oh goodie. 13 bits of switching noise from the RPi, and all the aliases. I’m sure that will be very useful for examining the realtime operation of the Linux operating system scheduler inside the Pi.

    Seriously though, I hope the designers pay close attention to this problem, which significantly affects similar devices like the RadioBerry.

  2. Jake Brodsky

    Something is odd here. They’re claiming 4 MSPS, and also a 4 MHz bandwidth? Do the samples include more than just I and Q? Nyquist theorem says they should have a bandwidth of 2 MHz or less for a 4 MSPS rate.

    I detect a need to explain some things here.

  3. Johm Mood


    I’m thinking you don’t have a clue to whom you are talking. I’ll let your vain attempts at insult go.

    I’m an Extra class amateur in the USA and have been a ham for over 35years, verifiable QRP contacts with the Space Shuttle while it was still flying, and plenty of ISS and other contacts. As to the SDR topic, it’s a large market, and getting larger, and I’ve enjoyed that too. So keep your opinions to yourself lease, they have been of no worth to me, I’ve done the research.

      • John Mood

        Who is being offensive? I mentioned a low price point and come schmuck accuses me of knowing nothing about radio? I’d call him offensive. I have been at radio for a very long time, and I get offended. Perhaps be more specific who you say I’d being offended and who the offender is please.

      • John Mood

        I’m not the one cursing either. All these pseudonyms make me thing one person is feeding the thread with offensive comments.

        I’m hoping the price point on the kit will be reasonable. $300.00 seems rather high when bought in quantity and sold as a kit, or built in the orient somewhere.

  4. Dave H

    I’m looking forward to seeing what price this comes in at. It could be a lot of fun if it’s as economical as RTL-SDRs, Raspberry Pis, and other such devices.

    I just looked up the Microchip RF modem part they’re using, and it’s less than US$6 in small quantities. The FPGA is equally inexpensive. Looks like the “big dog” will be the mixer/synthesizer at $18-$22. (Although it drops to less than $10 in thousand quantities.)

    As a guy who grew up on vacuum tubes and discrete transistors, I’m constantly amazed at how much functionality manufacturers can stuff into ICs that they sell for lunch money. What a long strange trip it’s been!

      • Dennis

        Ooooo, impressive board with lots of potential, and if you hook up good antennas that fit the band…. But, 300USD would be nice if they could make this for <100USD.

        • John Mood

          $300.⁰⁰ is either sarcasm or something else, considering reasonably capable DUAL SDR units for decoding trunked signals are way below $75.⁰⁰…

          Sarcasm isn’t my favorite than when people are genuinely interested in a new product, as I am.

        • Cyk

          You obviously don’t know what you’re talking about.
          You’re comparing a consumer grade 8-Bit single channel DVB-T receiver to a semi-professional 13-Bit dual channel receiver and transmitter.

          It should be noted that using the transmitter functionality, even inside the ISM bands, is illegal in most countries, without being a licensed HAM radio operator. In some countries, even the possession of this device is illegal.

          • John Mood

            A: I’m an American Licensed Extra class ham with 35 years plus experience. So far you haven’t told me anything I didn’t already know. B: Restriction to transmit doesn’t mean you can’t learn a great deal monitoring, which I do an enormous amount of.
            C: I’ve built from plans, and homebrewed my own with no plan. I’m not paying $300.00 for something I can get a review copy of, or build myself.

          • Cyk

            The comment was meant for Raspberry Pi tinkerers, who think that everything that they can buy and stack on their boards is automatically legal.

            • John Mood

              Just because they CAN do something doesn’t make it ok it legal. I’ve kept up with Amateur rules a long time, and anything that could transmit over a very broad set if frequencies is wide open for abuse by someone not rule compliant.

    • Lily

      the hardware is open source, so regardless of what price they charge for it anyone can just buy the parts and build it themselves.

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