Kraken sofware on a KerberosSDR with Pi3?


Recently, I bought a KerberosSDR and a Pi 3 to use for Radio Fox Hunting.
I downloaded and installed the Pi 3 image file and the system appears to have setup correctly using the web setup software.
I then tried to find and install the Kerberos App on my mobile phone.
Yep, the Kerberos App is no longer available.

So, I have installed the Kraken App instead.
I see that Kraken recommends using a KerberosSDR with a Pi 4.
And, surprise, surprise, the Pi 4 image doesn’t appear to work with my Pi 3.

So, is there anyway that I can use the Kraken app with a KerberosSDR with a Pi 3 ?
Perhaps there is a Pi 3 image file that I could download?

All help and advice will be most welcome.



Apologies if I have put this post in the wrong section, duplicated a topic, etc.

Response from Syed at Kraken:

The KrakenSDR RDF app on the Google Play Store will work with your KerberosSDR.

This page on the wiki describes the process of using a KerberosSDR with our KrakenSDR software.


Looking at the instructions, and with my not being a coder, I may need to ask for help in what they mean. :slight_smile:

@Nick_G4TAI Unfortunately, the Pi 3 just isn’t fast enough to run the direction finding software in real-time. The minimum requirement for a Raspberry Pi is a Pi 4B with 2GB of RAM.

Alternatively, you can try running the core software on a PC running Linux. That’s not as turnkey as burning an SD card image, though. You can also run the core software in a Docker container or Virtualbox on Windows. Again, this is not as straight forward as using a Pi 4.

Many thanks for the update.

I have now ordered a Raspberry Pi 4B with 8 GB of RAM.

In the meantime - noting:
There is a script in ~/krakensdr_doa/heimdall_daq_fw/util/ that can guide your through this. Just plug in your KerberosSDR (ensuring it is powered from the power port), and run the script ./

What software do I need to use to get to and run this script?
(I am a hardware / RF engineer not a software engineer.)

Many thanks.

You can run the EEPROM script on the Pi 4 itself.

  1. Ah! I read the instructions as meaning that the KerberosSDR EEPROM needs to be flashed. Not the Pi 3 / 4.
    Many thanks for clarifying.

  2. What software do I need to use to get to and then run the script within the Pi 4; when it arrives?
    (Sorry for such a software Newbie question.)
    Google suggested that scripts may be run from the CMD Prompt. But that doesn’t seem to work in this case.

No you were correct in the first place, the EEPROM on the Kerberos needs to be flashed. What I mean is that you can most easily run that command from your Pi 4.

To run it you can either attach a monitor and keyboard to the Pi 4, or you can SSH into the Pi 4 from your PC.

It Works! :smiley:
After plugging in a keyboard and monitor I can see the Kraken software on the screen!

I can now CD to the ~/krakensdr_doa/heimdall_daq_fw/util/ sub-directory.
However, the sh command falls over with an error after I enter Y.

So, whilst waiting for my Pi 4 to arrive, I am going to try installing the Kerberos App into an old phone to see if that works.

Many thanks to everyone for their help.

What’s the error that you get?

Sorry for the long delay.

This time I added bash before typing
The command now runs.

What’s the error that you get?

Going through the sequence, the software appears to only see #1 and #3.
I believe that their serial numbers are now 1000 and 1002.

Could the Kerborossdr be faulty?

Just ran ’ bash ’ again.

This software will initialize KerberosSDR EEPROM content and set serial numbers.
Found 3 receivers.
Do you wish to overwrite the current EEPROM content?

’ Y ’ Return

I have gone through this next part several times without success.
It usually asks for switches #1, #2, and #3 to be closed and opened. The 3 receivers that it finds?
This last time it asked for switch #0 to be closed. The missing receiver?

All good fun.

Repeated results:
#1 = serial number now 1000
#2 = device unsupported
#3 = serial number now 1002

Just a thought:
The 5V to the KerberosSDR might only be 2 amps (I am using a black Samsung charge r).
How many amps is recommended to run the KerberosSDR?

from a terminal try:

dmesg | grep -i "under"

If you see any lines like “Undervoltage detected!” you can be sure you need a higher current power supply

“Undervoltage detected!”:
I am using two of my Samsung mobile phone chargers to power my Pi 3 (with the Pi 4B image file) and Kerberos SDR.

The black charger should supply 2A.
However, I will input dmesg | grep -i “under” to check whether it is really supplying enough current. .

Either way, I will have to find my 5V at 5A power supply.

Many thanks.

Update: I typed dmesg | grep -i “under” but it didn’t run.
However, prior to that, I had swapped the 2 Amp black charger over to the Kerberos. Since then I haven’t seen the Undervoltage warning.

Test 4x Tuners (GitHub - rfjohnso/kerberossdr: KerberosSDR Demo software for direction finding and passive radar)
Open four terminal windows, or tabs, and in each window run “rtl_test -d 0”, “rtl_test -d 1”, “rtl_test -d 2” and “rtl_test -d 3”. Ensure that each unit connects and displays no errors.

rtl_test -d 0 / 1 / 2
Found 3 device(s):
0: RTL-SDR, KerberosSDR, SN: 1000
1: RTL-SDR, KerberosSDR, SN: 1001
2: RTL-SDR, KerberosSDR, SN: 1002

rtl_test -d 3
No matching devices found.

Does this confirm that one of the RTLs is faulty? (None of them are running any warmer nor cooler than the other three.)
If so, is there anything that I can do to re-activate it, e.g. re-flash the Kerberos EEPROM back to its original out-of-the-box settings?

Any help will be much appreciated.

Yes seems like one device is faulty if rtl_test is not seeing it. Double check that the DIP switch is not half way or something.

I’m curious though, where did you purchase the KerberosSDR? We haven’t sold KerberosSDR in a long time.

Hi Carl, Many thanks for replying once again.

  1. I have checked the DIP switches. All four read zero ohms when closed. And all four read the same resistance across them when open. A little over 2 Mega ohm, if I remember correctly.
    With their all having the same resistances, this suggests that these parts of the #2 receiver circuit is working correctly.

  2. I bought the Kerberos from eBay for £60.00
    Used: Buy it Now. Description: “Used briefly but have too many other projects to do.”
    Earlier today, I let the seller know that there is a problem. Adding that, with my just having bought a Pi 4B (and a Pi 3 just before that), I would rather get the Kerberos working if I can rather than return it and have no further use for the Pi 3 and Pi 4B.

3a) The following ramblings are included, as were the ramblings within my previous messages, in the hope that you will have an Ah Ha moment and suddenly realise what needs to be done to fix the problem. :- )

3b) At the moment, with the Pi 3 image loaded into the Pi 3 (the Pi 4B hasn’t arrived yet), and using 192.168… to connect to it, I have noticed that the four Spectrum displays don’t appear when requested and also that the sampling rate is -ms. (However, the four spectrum graphs are shown when the Pi 3 is connected to a monitor but the four traces remain static.) The latter -ms suggesting that the software isn’t sampling correctly; if at all. .
Have you any ideas what might be causing these two issues?
And how they might be fixed?

  1. Would an, effectively, factory reset of the Kerberos a good way to start with solving the problem(s)?
    If so, what would I need to do to perform this reset?
    At least we would then have a known benchmark from which we know the Kerberos should be working.


PS: whilst it must be abundantly clear that I am not a software engineer, I have been an electronics hardware engineer for many years. So, that’s another reason why I would love to get this Kerberos working properly.
That and I intend to use it for some of our local weekly radio fox hunting events. :slight_smile:

The Pi 4B has arrived. The Kerberos v1.6.1 firmware has been added.
As expected, still only 3 receivers being detected.

There’s no way to factory reset the Kerberos. The only thing that can change is the EEPROM strings, but that won’t affect it not showing up in rtl_test.

If one of the tuners isn’t working, the software won’t load properly at startup.

Unfortunately not much that can be done if one of the tuners has failed…this happened very rarely on the Kerberos, but it can definitely happen.

You could still run it as a three antenna DFing system, if you modify the DAQ settings to use three channels only. But with three antennas you do limit your DFing ability.

Hi Carl,

Once again, many thanks for all of your help. (And for the help that others have given me.) :smiley:

So, it looks like I will have to send the KerberosSDR back for a full refund. :frowning:

Then, I will have to find other uses for the Pi 3 and Pi 4B that I needed to buy.

Who knows, I might even learn a bit of coding as well. :slight_smile:

Best wishes.