The ultimate goal of this station was to establish a permanently working passive radar for research and development purposes. Passive radar is an emerging technology which is still not fully mature. In order to evolve reliable systems experimenting on real hardware is inevitable.
On the other hand the scientific value of a large amount of labeled data can be invaluable. The continuous operation of this newly installed passive radar station will hopefully enrich the scientific community with a huge amount of the valuable IQ samples.
The radar station is designed to utilize FM transmissions as the IoO (Illuminator of Opportunity). Using the local and distant FM broadcast towers the radar can detected passing airplanes in 360 degree. In order to cover this wide angle of view it utilize circular antenna system with Yagi antennas as the single element radiators. Six three-element Yagi antenna make up the surveillance antenna system, while one five-element Yagi antenna is responsible for the clean reference signal reception.
The coherent signal reception has been implemented with RTL-SDRs. For more detailed description of the used HR7 RF receiver and data acquisition system please check this page. Using this receiver not only the total cost of the station could be minimized, but further support has been made possible for those who are using this wide spread software-defined radio.
As these Realtek chip based radios are able to handle 2.4 MHz bandwidth, it is possible to utilize multiple IoOs simultaneously. This capability opens the way to carry out frequency diversity researches and developments.
The radar station is fully accessible remotely. Other than basic controlling, the firmware of the data acquisition subsystem and even the DSP core code can be updated. From the station it is possible to download raw IQ samples for research/development purposes or to download only the processed detections in track format. In normal operating conditions the radar station is sending tracks only and stores the interesting raw IQ samples localy.
Building the station in pictures
Please find bellow some pictures and their short description about the establishment of the station.
I Would like to express my gratitude to Levente Dudás and István Fuló. They help a lot on the build of this station.
The schematic arrangement of the antenna system is illustrated in Figure 25. The surveillance antenna array consist of 6 3 element Yagi antenna.
Figure 25: Fox station antenna system