Unleash the Kraken(SDR): 5-Channel Coherent Capable RTL-SDR Coming Soon (Direction Finding, Passive Radar)

Back at the end of 2018 we successfully crowdfunded KerberosSDR on Indiegogo which was our first coherent capable RTL-SDR that consisted of four RTL-SDRs on a common clock, with built in noise source and phase synchronization hardware. KerberosSDR enabled interesting experiments such as radio direction finding and passive radar to be implemented at a much lower cost.

KerberosSDR has taught us many things, and we're now working on the next iteration which will be a significantly refined version known as "KrakenSDR". KrakenSDR will be a five channel common clocked RTL-SDR, with built in noise source and automatic phase synchronization hardware.

KrakenSDR will be crowdfunded on CrowdSupply, and we currently have a pre-launch page active at crowdsupply.com/krakenrf/krakensdr

Please sign up to the CrowdSupply KrakenSDR email list on the CrowdSupply page to be notified once crowdfunding is launched so that you will be sure to catch the early bird pricing discounts. We expect to be able to launch sometime within the next two months.

KrakenSDR Prototype with 5-Magnetic Whip Antennas

Unlike KerberosSDR, KrakenSDR has built in switching hardware that when combined with the new software, will automatically achieve sample and phase calibration without needing to manually disconnect the antennas each time the unit is powered up, or each time the frequency is changed. This allows for much easier mobile and remote use scenarios.

The addition of the fifth tuner also allows us to use a five element antenna array, which results in much improved direction finding accuracy and better multipath rejection. USB-C is also now used on both ports for greater port reliability, the PCB has been redesigned for lower noise, software controlled bias tees are present on each port, and it comes in a tough CNC milled enclosure that doubles as a heat sink.

Finally there is a new open source software base which uses the new synchronization hardware to perform auto phase calibration, allows for intermittent signals to be squelched and tracked, enables long term phase synchronization monitoring, and enables new possibilities for future code expansion especially for passive radar which we will be testing in the upcoming months.

Below are three videos demonstrating the KrakenSDR in action. Please subscribe to the KrakenSDR YouTube channel for more upcoming demonstrations.

KrakenSDR Radio Direction Finding Compass Test 1

KrakenSDR Radio Direction Finding Retune with Autocalibration Test 1

KrakenSDR Vehicle Radio Direction Finding Demonstrations

If you haven't seen them yet, it may also be interesting to watch our old KerberosSDR videos as well in the playlist below.

KerberosSDR Radio Direction Finding: Heatmap + Auto Navigation to Transmitter Location Demo 1

Some of our previous KerberosSDR posts might also be of interest.

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Josph Cooper VE3FMQ

My local repeater has been targeted by very persistent jammer and this would be an excellent tool for tracking them down. Please keep me posted on your progress.


Any updates 🙂 Really looking forward to getting one of these.


Any updates? Really jonesing for this super neat radio


Any news when it will be out on the market?


From the above article “We expect to be able to launch sometime within the next two months”, so since that was posted 2021-04-06, that would imply possibly this month or next month for the CrowdSupply crowdfunding campaign to begin, probably a 4 to 8 weeks before that ends. Then once they are funded, and the money is released, then there is lead time on ordering parts. It used to be on average about 6-8 weeks but with problems globally, even some passives have a lead time of 16 weeks to 52 weeks ( ref: https://a2globalelectronics.com/market-update/ ). So if somewhere like mouser/digikey/lcsc/… do not have enough stock, they could end up waiting on a bad lead time for one component before manufacturing can begin. And then there is shipping delays to manufacturing, testing, and final shipping.

With 10 boards, all these problems vanish, but as the numbers ramp up the problems that add delays do as well. That would be my 2 cents on it anyhow. All of what I said above changes if the people at rtl-sdr.com have a massive cash reserve, or take out a very large bank loan. But that could be risky.


I wasn’t aware of the political connection, but instead went right for the BattleBots connection. Not the most vicious bot, but a tough mother!



Couldn’t the Kraken or the Kerberos also be used for diversity reception? Yes, it would take software support, but is there anything would prevent the hardware from being used as such?


Very interesting “technical” discussion.


Well, how much will one (1) piece cost? And i really hope those antennas from the images are an optional accessory (unlike identity politics etc. nowadays. “play your banjo well”)


Nothing wrong with this announcement at all. The Kraken should be referenced to an amazing supercomputer that was decommissioned in the early 2010s. Disconnect from mainstream media and listen to what is actually going on in your area with your SDR.. 🙂

Robin, G8DQX

Luckily, the Kraken means only one of two things:
a) The Kraken Wakes, by John Wyndham (well worth a read)
b) that Kraken, in Norse, includes its own definite article, making a “The” before Kraken arguably spurious
Until I came across it here, I had no idea that there were Kraken (it’s its own plural) in the Potomac!


If you’re in South Padre Island, Texas, it means a prominent tattoo parlor 🙂


Will there be an interface to stack two or even more KrakenSDRs to a single n x 5 channel coherent receiver?
I think there were some “for future use” etc. informations given for the KerberosSDR intending that at least using two KerberosSDRs coherent might be possible but as far as i know no detailed explanations or official support was released.
It might be an interessting starting point for phased arrays without developing a hardware first ()

Douglas Ward

The problem with this announcement is the association with “the Kracken”, which is a huge and unnecessary political issue in connection with Donald Trump, Sidney Powell, etc.


Scandinavian here.
Never heard of the word kraken beeing connected to trump.
I came to think of a brand of rum.
And in the end, allmost everything controversial and weird can be connected to trump or US politics…


Also never heard of the kraken in relation to any internal US politics.

My first thought was the 1981 film Clash of the Titans or even the 2007 film Pirates of the Caribbean: At World’s End. Or even the actual original thousand year old Scandinavian folklore.


I think of the mythical beast or the rum. Maybe you should get over OJ Man.