Tagged: krakensdr

KrakenSDR: Passive Radar Demonstration

KrakenSDR is a 5-tuner coherent software defined radio based on RTL-SDR. It is the successor to the KerberosSDR and will be crowdfunded on Crowd Supply in a couple of months time. Please sign up to the KrakenSDR Crowd Supply mailing list to be notified as soon as the campaign begins.

The KrakenSDR (prototype - enclosure may change slightly)

Passive Radar uses existing FM, TV or mobile phone transmitters. The signal from these transmitters reflects off objects such as road vehicles and aircraft. By using two antennas on two receive channels, and an algorithm to compare the reflected signal against a clean reference copy of the actual signal, we can achieve a radar like display of bi-static range vs doppler speed.

In this test KrakenSDR is used as a two antenna passive radar system. The reference antenna points towards a horizontally polarized 620 MHz DVB-T transmitter, and the surveillance antenna points towards an Airport.

Passive Radar setup with two TV Yagis

Reflections of aircraft and road vehicles can be seen on the map as red dots/trails. Notice how we can also determine the overall neighborhood activity of road vehicles as we pointed out in a previous KerberosSDR post.

Of note is that we've placed the surveillance antenna in a vertically polarized configuration. With passive radar you want to keep the reference signal out of the surveillance channel, as ideally the surveillance channel only receives the reflections. Using the surveillance antenna in vertical polarization achieves 20dB attenuation of the horizontally polarized DVB-T signal. The reflections are assumed to be randomly polarized, so the vertically polarized antenna should pick up the reflection just the same no matter what polarization is used. This scheme woks especially well in our setup as the angle between the reference transmitter and target reflected objects is small.

This test uses the older KerberosSDR code (slightly modified to allow for trails), however new passive radar code is being worked on for the new KrakenSDR code base which will be released later this year. We expect the new code to also be able to make use of GPU accelerated CUDA hardware, such as the NVIDIA Jetson. This will allow for a much faster update rate and/or more processing gain.

The new KrakenSDR code will also try to make use of the additional three unused channels. With these extra channels we should be able to add a direction finding array that will help to plot on a map the actual location and elevation of the reflections.

KrakenSDR Passive Radar Demonstration 1

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.