Article Figures & Data
Figures
- FIGURE 1
Comparison of the two array topologies under consideration (a) Conventional uniform rectangular array (b) Combination of two linear subarrays
- FIGURE 2
Examples of places in which the ULAs can be mounted in the synthetic parts of a passenger car
- FIGURE 3
Coordinate system, direction of arrival (DOA) and relative delays compared to the origin for a signal incident from ϕi = 150° and θi = 40°
- FIGURE 4
Absolute values of the impulse response for a distance of 4 m for two different sampling rates fs (a) fs = 5 MHz as used to sample narrowband signals, e.g., GPS L1 C/A (b) fs = 25 MHz as used to sample wideband signals, e.g., GPS L5 or GALILEO E5a
- FIGURE 5
Block diagram of the beamforming implementation
Potential interference is mitigated by decorrelating the raw antenna signals. The satellite signals are independently amplified after demodulation and despreading using the correlator outputs of the tracking channels.
- FIGURE 6
Comparison between the state-of-the-art SAP and the proposed STAP implementation for
(a) Conventional SAP block diagram (b) Proposed STAP block diagram for M = 3 tapsShown is an example using N = 4 antennas.
- FIGURE 7
Behavior of the impulse response hFD[k] over bandwidth fs (a) |hFD[k]| depending on fs for a delay of 4 m. The color denotes the magnitude of the channel tap (b) Power of the central channel tap of hFD[k] relative to the power in all other taps over fs for different baselines
- FIGURE 8
STAP performance over fs for a delay of 4 m (a) Correlation coefficients (b) Residual amplitude after mitigation for different STAP implementations
- FIGURE 9
Image and parameters for the measurement setup in VISTA (a) Image of the measurement setup in VISTA. Orange, green, and red circles mark satellite, jamming signal emitting antennas, and subarrays, respectively (b) Sketch of the setup
- FIGURE 10
Procedure to calculate ΔCN0 (a) Achieved CN0 with 3-tap STAP (b) Achieved CN0 with SAP (c) ΔCN0 between STAP and SAP
The CN0 achieved using STAP and SAP were subtracted for each satellite. The green- and yellow-highlighted areas mark the intervals where only SAP or both SAP and STAP lost the signal.
- FIGURE 11
Improvement observed with STAP with M = 3 compared to SAP for GALILEO E5a signals (a) ΔCN0 for DOA 1 (b) ΔCN0 for DOA 2 (c) ΔCN0 for DOA 3 (d) ΔCN0 for DOA 4
- FIGURE 12
Improvement observed with STAP with M = 5 compared to STAP with M = 3 for GALILEO E5a signals (a) ΔCN0 for DOA 1 (b) ΔCN0 for DOA 2 (c) ΔCN0 for DOA 3 (d) ΔCN0 for DOA 4
- FIGURE 13
Improvement observed with STAP with M = 3 compared to SAP for GPS L1 C/A signals (a) ΔCN0 for DOA 1 (b) ΔCN0 for DOA 2 (c) ΔCN0 for DOA 3 (d) ΔCN0 for DOA 4
- FIGURE 14
Measurement setup at the Chair of Navigation in Aachen (a) Jamming antenna near the car (b) Array on the front bumper (c) Reference antenna on top of the roof
- FIGURE 15
Properties of the jamming signal during the experiment (a) Jamming power over time (b) Eigenvalues of
of the array antenna signals over time (c) Spatial distribution of received signals GAL/GPS, satellites; JAM, jammer - FIGURE 16
Position accuracy in Earth-centered, Earth-fixed (ECEF) x,y and z and number of satellites (a) Roof Antenna (b) Array with SAP (c) Array with STAP with M = 3
The lower figures show the sum over the absolute values of all three coordinates in combination with the jamming power as shown in Figure 15(a).
Tables
Property Value Jamming Signal Generator Anritsu MG3710E Jamming Signal White Gaussian Noise with 20 MHz bandwidth at L5 center frequency (f = 1.17645 GHz) Jamming Power PTX from −80 dBm to 15 dBm ramped up within 95s in steps of 0.25 dB Jamming antenna Schwarzbeck CLSA 0110R Receiving antennas Tallysman TW7875 with Tallysman TW155 Bias-Tees Capturing devices USRP X300 with 2x Twin-RX daughterboards Sampling rate fs = 25 MHz
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