Article Figures & Data
Figures
- FIGURE 1
Schematic representation of RIM techniques.
- FIGURE 2
Variance of pseudorange measurements as a function of the estimated 𝐶∕𝑁0. Crosses represent variances estimated from the measurements obtained for Test 1; different colors indicate different satellites. Upper part: GPS L1 C/A measurements. Lower part: Galileo E1c measurements.
- FIGURE 3
Experimental setup adopted to test the impact of robust jamming mitigation techniques on measurements and position solutions. a) Schematic representation of the setup. b) Actual view of one of the experiments involving Galileo E5b signals.
- FIGURE 4
The two jammers used for the tests: a) Battery powered jammer in the shape of a cordless phone used for Test 1 and Test E5b. b) Battery powered jammer with SMA connector and detachable antenna used for Test 2.
- FIGURE 5
Estimated 𝐽∕𝑁 profile of the first test conducted on the GPS/Galileo L1 frequencies. In the box: spectrograms of collected samples at the beginning of the test and after 900s. The zero frequency corresponds to 1575.42 MHz. After about 400 seconds from the start of the test, front-end saturation occurs, and the estimated J / N starts flattening out.
- FIGURE 6
𝐽∕𝑁 profile estimated for the second test conducted on the GPS/Galileo L1 frequencies. In the box: spectrograms of collected samples at the beginning of the test and after 500s. The zero frequency corresponds to 1575.42 MHz. After about 500 seconds from the start of the test, front-end saturation occurs, and the estimated 𝐽∕𝑁 starts flattening out.
- FIGURE 7
𝐽∕𝑁 profile estimated for one of the experiments conducted in the Galileo E5B band. In the box: spectrograms of collected samples at the beginning of the test and after 500s. The zero frequency corresponds to 1207.14 MHz. After 500 seconds from the start of the test, a minimum attenuation equal to 20 dB was obtained. This attenuation is kept constant for two minutes and increased again.
- FIGURE 8
Comparison between 𝐶∕𝑁0 time series obtained without mitigation and using the TDCS approach for Test 1. Dashed lines refer to 𝐶∕𝑁0 values obtained using standard processing without mitigation. GPS L1 C/A signals.
- FIGURE 9
Pseudorange differences between standard measurements and observations from the five interference mitigation techniques. The ANF has been tested for two values of 𝑘𝛼, the pole contraction factor. Test 1, GPS L1 C/A.
- FIGURE 10
Pseudorange differences between standard measurements and observations from the five interference mitigation techniques. The ANF has been tested for two values of 𝑘𝛼, the pole contraction factor. Test 1, Galileo E1c.
- FIGURE 11
Position errors in the ENU frame. Comparison between different interference mitigation techniques for GPS L1 C/A only positioning. The shaded areas indicate the portion of the test where jamming can be neglected. Test 1, 8 bits. “LoP” is used to indicate loss of position solution.
- FIGURE 12
Position errors in the ENU frame. Comparison between different interference mitigation techniques for Galileo E1c only positioning. The shaded areas indicate the portion of the test where jamming can be neglected. Test 1, 8 bits. “LoP” is used to indicate loss of position solution.
- FIGURE 13
Pseudorange differences between standard measurements and observations from the five interference mitigation techniques. The ANF has been tested for two values of 𝑘𝛼, the pole contraction factor. Test 2, GPS L1 C/A.
- FIGURE 14
Position errors in the ENU frame. Comparison between different interference mitigation techniques for GPS L1 C/A only positioning. The shaded areas indicate the portion of the test where jamming can be neglected. Test 2, 16 bits. “LoP” is used to indicate loss of position solution.
- FIGURE 15
Pseudorange differences between standard measurements and observations obtained using interference mitigation techniques. The ANF has been tested for two values of 𝑘𝛼, the pole contraction factor. Galileo E5b experiment.
- FIGURE 16
a) PSDs of the signals at the input and output of the ANF for 𝑘𝛼 = 0.8. The ANF transfer function is also provided. The transfer function of the ANF has been shifted in order to improve clarity. b) Spectrogram of the collected samples and frequency of the ANF notch (red dashed line). E5b test, samples collected after 400 seconds from the start of the experiment.
- FIGURE 17
Position errors in the ENU frame. Comparison between different interference mitigation techniques for the Galileo E5b experiment. The shaded areas indicate the portion of the test where jamming can be neglected. “LoP” is used to indicate loss of position solution.
- FIGURE 18
Position RMSE as a function of the estimated 𝐽∕𝑁. Left) Horizontal component Right) Vertical component. Comparison between different interference mitigation techniques for the Galileo E5b experiment.
Tables
Technique Parameter Value Comments and references ANF Pole contraction factor, kα [0.7,0.9] For swept interference (Borio, O’Driscoll, and Fortuny, 2012; Qin, Dovis, et al., 2019; Qin, Troglia Gamba, et al., 2019; Troglia Gamba et al., 2012; Wendel et al., 2016) [0.9,0.98] For CWI (Calmettes et al., 2001; Raasakka & Orejas, 2014; Troglia Gamba et al., 2012) Adaptation step, δ 
(Calmettes et al., 2001; Qin et al., 2019; Wendel et al., 2016) PB Decision Threshold, Th αTσ Require noise floor estimation (Bastide, Chatre et al., 2004; Raimondi et al., 2008; Rugamer et al., 2017; Wang et al., 2010) quantization level Noise floor estimated by the AGC (Bastide, Macabiau et al., 2003; Borio & Cano, 2013; Hegarty et al., 2000) complex signum Parameter free (Borio & Closas, 2018) Test 1 Test 2 Test E5b Parameter Value Value Value Sampling Frequency 10 MHz 10 MHz 25 MHz Center Frequency 1575.42 MHz 1575.42 MHz 1207.14 MHz Sampling Type Complex, IQ Complex, IQ Complex, IQ No. bits 8 16 8
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