KrakenRF Software Defined Radio
KrakenRF Software Defined Radio (KrakenSDR) is a coherently operated, five-RX-channel radio based on the RTL-SDR, allowing radio direction finding and beamforming. KrakenSDR uses five custom RTL-SDR circuits consisting of R820T2 and RTL2832U chips. To achieve phase coherence, KrakenSDR drives all five RTL-SDR radios with a single clock source and contains internal calibration hardware to allow the phase relationship between channels to be measured precisely and corrected in software. Additionally, the overall design of KrakenSDR works to ensure phase stability, with care taken in heat management, driver configuration, power supply, and external interference mitigation.
The coherent SDR software provides 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 Raspberry Pi 4 or similar single-board computer (SBC) but can also run on a Linux PC. Open-source DSP code supports radio direction finding. That code implements direction-finding algorithms such as MUSIC, which can run on the same Pi 4 or PC as the DAQ code. An Application Layer uses the data from the DSP layer by plotting and logging it. Generally, programs in this layer run on a separate machine. For direction finding, a free Android app for mapping, logging data, and automatically estimating the transmitter location is provided.
The KrakenSDR software comes with an easy-to-use web interface for setting up direction-finding parameters. This interface allows users to set the frequency, gains, VFOs, and other advanced settings. Customers can also monitor the live-spectrum view and graphs of output from the direction-finding algorithm.
In addition to the web interface, a companion radio-direction-finding Android app can automatically determine a transmitter's location. Since a typical Android phone has capabilities that include necessary sensors and software like GPS, compass, mobile data, and mapping, KrakenR used those features to create an affordable radio direction-finding system. The application automatically and accurately calculates the map bearing towards the searched transmitter for that particular location. The app then logs this data and plots it on a map grid, which is used to determine where the bearings intersect automatically. Generally, it will only take a few minutes of driving to locate a transmitter with a solid continuous signal accurately. The app then goes a step further and provides automatic turn-by-turn navigation. The app is free for KrakenSDR backers to download.
Features
- Five-channel, coherent-capable RTL-SDR, all clocked to a single local oscillator
- Built-in automatic coherence synchronization hardware
- Automatic coherence synchronization and management via provided Linux software
- 2.56MHz bandwidth
- 24MHz to 1766MHz tuning range (standard R820T2 RTL-SDR range, and possibly higher with hacked drivers)
- 4.5V bias tee on each port
- 5x channels improves-direction finding accuracy
- Core DAQ and DSP software is open source and designed to run on a Raspberry Pi 4
- Direction-finding software for Android (free for non-commercial use)
- Custom antenna set available
- Clean spectrum with low internal noise
- Heavy-duty CNC aluminum case, 160mm x 120mm x 20mm dimensions
- 5V operating supply voltage
Applications
- 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
- Locating lost ships via VHF radio
- 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
- Beamforming
- Interferometry for radio astronomy
Required Equipment
- KrakenSDR
- USB Type-C™ cable
- 5V, 2.4A+ USB Type-C power supply
- Antennas, such as the magnetic whip antenna set
- Raspberry Pi 4 or such device for computing
- Android phone or tablet with mobile hotspot capabilities, GPS, and a compass, ideally produced within the last three to four years
Videos
Overview
Related Antennas
KrakenRF KRAKENANT-01 Magnetic Whip Antenna Set
Set of five magnetic whip antennas that can be used with the KrakenSDR for direction finding.