Experimental measurements

A number of field measurements have been carried out to test the operation of the RTL SDR based passive radar receiver system. In this page the obtained results and some experiences are shared and discussed.

Measurement #1

The first measurement is made in a fairly controlled environment to test the basic operation including simple target detection and detection with A-DPIS. During the measurement landing airplanes have been observed as the trajectory of the consecutively approaching airplanes can be assumed to be very similar, thereby ensuring comparable and repeatable measurements. The map of the measurement scenario is depicted in the following pictrue.

IO parameters:

  • IO location: Széchenyi-hill

  • TX power: 77.6 kW

  • Frequency: 89.5 MHz

  • Broadcast station: MUSIC FM

Two 5 element Yagi antennas have been used. One for the reference channel (left one on the picture) and one for the surveillance channel (right on the picture bellow). The remaining antennas on the picture bellow belong to a DVB-T based  system which was used as a control equipment.

A range-Doppler map obtained from the measurement data can be seen in the next figure, where two detected airplanes are visible. In the results below one sample delay corresponds to 1500m.

Processing parameters:

  • Bandwidth: 200 kHz (Decimation with 12 from 2.4 MHz)

  • CPI: ~ 163 ms

  • Clutter filter: Wiener-SMI

In the next animation, the consecutively calculated range-Doppler maps can be seen. The landing airplane can easily be identified.

Measurement #2

The main objective of this experiment was to investigate the possibility of using lower power local broadcast stations for aerial surveillance. While in the previous experiment, the transmitter power was 77 kW, in this scenario a transmitter with  3 kW TX power has been utilized. In the figures below the map and the measurement scenario is illustrated.

In contrast to the first measurement, in this experiment we observed high altitude passing airplanes. These planes had an average flight altitude of 11 km.

IO parameters:

  • IO location: Uzd

  • TX power: 3 kW

  • Frequency: 90.3 MHz

  • Broadcast station: Petőfi radio

Target parameters:

  • Flight altitude: ~ 11 km

  • Airplane type: Airbus A321-231

  • Velocity: 210 m/s

Processing parameters:

  • Bandwidth: 200 kHz (Decimation with 12 from 2.4 MHz)

  • CPI: ~ 325 ms

  • Clutter filter: Supplemented ECA-S

The airplane is also visible in the range-Doppler domain. On the positive Doppler frequencies the airplane is approaching to the receiver from the rear. Accordingly the reflected signal is received with the back lobe of the surveillance antenna and thus the received signal has less power. In contrast, when the target moved away, it rather resided in the main lobe of the antenna, thus it is more visible. From the measurement we can conclude that the low power local broadcast stations can also be applied with promising results.

Measurement #3

In the third measurement, we made experiment regarding to the utilization of distant IOs.

IO parameters:

  • IO location: Széchenyi-hill

  • TX power: 77 kW

  • Frequency: 89.5 MHz

  • Broadcast station: MUSIC FM

  • Baseline distance: 100 km

Processing parameters:

  • Bandwidth: 200 kHz (Decimation with 12 from 2.4 MHz)

  • CPI: ~ 325 ms

  • Clutter filter: Supplemented ECA-S

According to the results we can declare that transmitter towers from large distances can be applied for local surveillance. With increasing the number of available bistatic pairs the target parameters can be measured even more precisely or its exact location can be calculated without direction of arrival estimation.

This site was designed with the
.com
website builder. Create your website today.
Start Now