Effects Of Continuous Wave Interference Research Articles

Effect of Continuous Wave Interference on GNSS Receivers

The positioning performance of GNSS receivers is strongly influenced by radio interferences, especially continuous wave interference (CWI). Recent studies have modeled the effects of the interference and have shown that the effect of the interference is strongest where the frequency offset between CWI interference and the GNSS signal is a multiple of 1KHz. However, these studies have not yet modeled the effect of phase offset between CWI interference and signal which has a significant impact on the positioning performance. In this paper, we present the effect of CWI interference on positioning performance considering the role of both frequency and phase offset. In addition, theoretical and simulation results also show that CWI noise does not significantly affect the signal with some specific values of phase offset.

Effects of CW Interference on the BDS Receiver and Analysis on the Coupling Path of Electromagnetic Energy

The present research is carried out on the issue that the BDS (BeiDou Navigation Satellite System) receiver exerts some vulnerability to CW (continuous wave) interference. The analysis on the interference mechanism of navigation signal is implemented based on the model of direct sequence spread spectrum communication system while the method of parallel code phase search is employed to simulate the capture capability of the receiver under CW interference. In the CST-MWS, the simulation was made for the coupling path and electromagnetic energy into the navigation receiver, concluding that the antenna functions as the major obtained coupling path. On that basis, the RF radiation interference experiment for the antenna of the BDS receiver was conducted in the semi-anechoic chamber. In addition, the RF injection interference experiment was made on the basis of the power coupler. The sensitive frequency band of the receiver under the interference was obtained through the experiment. Furthermore, findings are made that the ratio of the output power of the RF signal generator under the RF irradiation method to the output power with the RF injection method takes no variation with change of the interference frequency. Therefore, The RF injection method can be used instead of RF irradiation method under CW interference in order to gain simplified experimental equipment, which provides a more professional theoretical basis for anti-interference research.

Increase of Carrier-to-Noise Ratio in GPS Receivers Caused by Continuous-Wave Interference

The increased use of personal private devices (PPDs) is drawing greater attention to the effects of continuous-wave interference (CWI) on the performance of global positioning system (GPS) receivers. The effective carrier-to-noise density ratio (C/N0), an essential index of GNSS receiver performance, is studied in this paper. Receiver tracking performance deteriorates in the presence of interference. Hence, the effective C/N0, which measures tracking performance, decreases. However, simulations and bench tests have shown that the effective C/N0 may increase in the presence of CWI. The reason is that a sinusoidal signal is induced by the CWI in the correlator and may be tracked by the carrier tracking loop. Thus, the effective carrier power depends on the power of the signal induced by the CWI, and the effective C/N0 increases with the power of the CWI. The filtering of the CWI in the carrier tracking loop correlator and its effect on the phase locked loop (PLL) tracking performance are analyzed. A mathematical model of the effect of the CWI on the effective C/N0 is derived. Simulation results show that the proposed model is more accurate than existing models, especially when the jam-to-signal ratio (JSR) is greater than 30 dBc.

Performance Comparison of Code Discriminators in the Presence of CW Interference

This paper considers the effect of continuous wave interference (CWI) on code tracking loops for global navigation satellite system signal. Based on the integrate-dump model analysis, the overall correlation results in the presence of CWI are theoretically analyzed incorporating the sum frequency interference terms which were regarded as negligible quantities in previous studies. Using the obtained correlation results, the closed-form expressions of the code tracking errors caused by CWI for three types of code discriminators (coherent, noncoherent, and barycenter) are derived and formulated as the solutions of quadratic equations using reasonable assumptions of trigonometric functions. Simulations are performed to demonstrate the accuracy of the theoretical correlation results. Also, the simulated code tracking errors are also presented to corroborate the effectiveness of the closed-form code tracking errors in terms of interference parameters (frequency and phase). It is indicated that the barycenter discriminator has the superior performance and could be preferred for mitigating CWI in tracking stage. These results can be applied for performance comparison, signal design, receiver design, and interference mitigation techniques in the presence of CWI.

A preventative approach to mitigating CW interference in GPS receivers

In the global positioning system (GPS), code division multiple access (CDMA) signals are used. Because of the known spectral characteristics of the CDMA signal, continuous wave (CW) interference has a predictable effect on the different pseudo random noise (PRN) spreading codes (unique to each satellite) depending on the Doppler frequency of the signal. The Doppler frequency for each signal is also predictable once the receiver position is known. As different satellite signals have different Doppler frequencies, the effect on the signal quality is also different. In this paper first the effect is studied analytically. The concept of an “exclusion zone” is defined and analyzed for each satellite. This exclusion zone, where that satellite should not be used due to interference degradation, is shown to be predictable for each satellite as a function of time. Using this prediction, the CW interference effect on the positioning quality of the receiver can be mitigated by ignoring the affected satellites within exclusion zones when performing position evaluation. The threshold beyond which a satellite should be excluded is then derived by studying the mutual effects of the geometry and the signal quality of that satellite on the positioning quality. Receiver autonomous integrity monitoring (RAIM) uses redundancy in measurements to perform an internal consistency check to see if all of the measurements are satisfactory. In this paper this technique is also used to mitigate the effect of CW interference on the positioning accuracy. Finally it is shown that the prediction of the exclusion zone for each satellite outperforms the RAIM algorithm in mitigation the effect of the interference when 5 satellites are visible.

Effects of CW interference on phase-locked loop performance

This paper focuses on the modeling and analysis of phase-locked loops in the presence of continuous wave (CW) interference such that the operating vulnerability to CW jamming and interference can be accessed. The loop phase error is characterized, and the conditions under which the loop remains locked in frequency to the desired carrier are presented. Analysis is conducted for arbitrary offsets of carrier and interferer signal frequencies relative to the quiescent voltage-controlled oscillator (VCO) frequency. The results show that loop performance depends not only on the frequency difference between the desired signal and interferer, but also on the frequency offset between the quiescent VCO oscillation and desired carrier. The vulnerability of the loop to the presence of interference increases if interferer and desired signal spectral locations are in opposite sides of quiescent VCO frequency.

Synchronous behaviour of mutually coupled phase-locked loops in the presence of continuous wave interference

Abstract An analysis is presented concerning the effects of continuous wave interference on the performance of two mutually coupled phase-locked loops with a sinusoidal phase detector characteristic. The parasitic phase error and the parasitic phase modulation introduced into the reconstructed carrier by the interfering signal have been examined for different loop parameters and an input carrier-to-interference ratio. The results show that the interfering signal will only influence the loop in which it occurs and no parasitic phase error will be introduced into the other loop.