KrakenSDR Radio 5-Channel SDR Receiver & Antennas for Radio Direction Finding Passive Radar
KrakenSDR is a Software-Defined, Coherently Operated, Five-RX-Channel Radio
A coherent radio allows for very interesting applications, such as radio direction finding, passive radar, and beamforming. Some use cases include:
- Physically locating an unknown transmitter of interest (e.g. illegal or interfering broadcasts, noise transmissions, or just as a curiosity)
- HAM radio experiments such as radio fox hunts or monitoring repeater abuse
- Tracking assets, wildlife, or domestic animals outside of network coverage through the use of low power beacons
- Locating emergency beacons for search-and-rescue teams
- Locating lost ships via VHF radio
- Passive radar detection of aircraft, boats, and drones
- Traffic-density monitoring via passive radar
- Interferometry for radio astronomy
KrakenSDR is KerberosSDR++
The previous version of KrakenSDR was known as KerberosSDR, which we successfully crowdfunded on Indiegogo. All backers of KerberosSDR received their orders and the relevant source code for direction finding and passive radar. KrakenSDR improves upon KerberosSDR in several important respects:
- Automatic calibration hardware. It is no longer necessary to manually disconnect antennas during calibration. It all happens automatically when you change frequency. This will allow for KrakenSDR stations to be remotely operated.
- Five channels. KrakenSDR has five channels instead of four, which greatly improves-direction finding accuracy.
- Low-noise design. KrakenSDR has a cleaner spectrum with much less internal noise than KerberosSDR.
- USB Type-C ports and rugged, CNC-milled enclosure. KrakenSDR is built for high reliability in the field.
- Interface with external devices. Bias tees on all ports allow for LNAs and other devices to be powered easily.
- Improved DAQ, DSP, and GUI software. Built on the foundation of the KerberosSDR software, the KrakenSDR software adds auto-calibration, tracking of intermittent signals, greater stability, arbitrary processing-block sizes, and a new web-based GUI.
- Software upgrades. Improvements to existing companion software and plans for new companion software.
- Custom App for Android. Custom App can automatically determine the location of a transmitter and provide automatic turn-by-turn navigation to the transmitter location.
Features & Specifications of KrakenSDR:
- Five-channel, all clocked to a single local oscillator
- Built-in automatic coherence synchronization hardware
- Automatic coherence synchronization and management via provided Linux software
- 24 MHz to 1766 MHz tuning Range (standard R820T2 range, and possibly higher with hacked drivers)
- 4.5 V bias tee on each port
- Core DAQ and DSP software is open source and designed to run on the board for Raspberry Pi 4 (see links below)
- Direction-finding software for Android (free for non-commercial use)
Features of Antennas:
- Made of rubber coated neodymium magnets
- Changeable cables and retractable antennas with SMA connectors
- LMR100 low-loss cable with a length of 2m/6.6ft
- Including 5 antennas. All cables are strictly electrically measured, so they have the same length. This is critical for applications that require phase coherence, such as radio direction finding
What Do You Need to Get Started?
You will need KrakenSDR, a USB Type-C cable, a 5 V / 2.4 A+ USB Type-C power supply, and antennas—such as our magnetic whip antenna set—that are appropriate for your application.
For computing we recommend a board for Raspberry Pi 4, for which we will be providing ready-to-use SD card images. Optionally, for direction finding, you will want an Android phone or tablet with mobile-hotspot capabilities, GPS, and a compass, ideally produced within the last three to four years.
How KrakenSDR Works?
KrakenSDR makes use of five custom circuits consisting of R820T2 and RTL2832U chips. Each one will receive signals at a slightly different phase offset from the others. This makes it difficult or impossible to achieve a high degree of precision when measuring relationships between signals that arrive at different antennas.
To achieve phase coherence, KrakenSDR drives all five radios with a single clock source, and contains internal calibration hardware to allow the phase relationship between channels to be measured precisely and corrected for. Additionally, the overall design of KrakenSDR works to ensure phase stability, with care taken in the areas of heat management, driver configuration, power supply, and external-interference mitigation.
Our coherent SDR software is based on three important factors:
- Open source. We provide open source code for the Data Acquisition (DAQ) software used to ingest RF data from all five antenna inputs, automatically calibrate and achieve phase coherence via the switches and noise source, and provide coherent samples for the next layer. This DAQ code typically runs on a Pi 4, or similar single board computer (SBC), but could also run on a PC.
- DSP code for specific use cases. Our open source DSP code supports direction finding and passive radar. That code implements direction-finding algorithms such as MUSIC, which can also run on the same Pi 4 or PC as the DAQ code. We also provide open source DSP code for our passive radar. (As passive radar is more computationally intensive, this particular DSP code may run best on a more powerful machine.)
- Application layer. We make use of the data coming out of the DSP layer by plotting and logging it. Generally, programs in this layer run on a separate machine. For direction finding, we are providing a free license to an Android app for mapping, logging data, and automatically estimating the transmitter location.
KrakenSDR Web Interface:
The new KrakenSDR software comes with an easy-to-use web interface for setting up a direction finding system. With this interface it is possible to set the frequency, gains, and other advanced settings related to the DAQ code. You can also monitor the live-spectrum view and graphs of output from the direction-finding algorithm.