Wide-Band Interference Mitigation in GNSS Receivers Using Sub-Band Automatic Gain Control

The performance of GNSS receivers is significantly affected by interference signals. For this reason, several research groups have proposed methods to mitigate the effect of different kinds of jammers. One effective method for wide-band IM is the HDDM PB. It provides good performance to pulsed and frequency sparse interference. However, it and many other methods have poor performance against wide-band noise signals, which are not frequency-sparse. This article proposes to include AGC in the HDDM structure to attenuate the signal instead of removing it: the HDDM-AGC. It overcomes the wide-band noise limitation for IM at the cost of limiting mitigation capability to other signals. Previous studies with this approach were limited to only measuring the CN0 performance of tracking, but this article extends the analysis to include the impact of the HDDM-AGC algorithm on the PVT solution. It allows an end-to-end evaluation and impact assessment of mitigation to a GNSS receiver. This study compares two commercial receivers: one high-end and one low-cost, with and without HDDM IM against laboratory-generated interference signals. The results show that the HDDM-AGC provides a PVT availability and precision comparable to high-end commercial receivers with integrated mitigation for most interference types. For pulse interferences, its performance is superior. Further, it is shown that degradation is minimized against wide-band noise interferences. Regarding low-cost receivers, the PVT availability can be increased up to 40% by applying an external HDDM-AGC.

A new kind of locked circuit: the Quasi-Periodic Locked Loop (Q-PLL)

A new nonlinear circuit with frequency locking capability in the case of a generic quasi-periodic input, is presented. Due to this capability the circuit is called a Quasi-Periodic Locked Loop (Q-PLL). The locked frequency is parametrically selected from among those prescribed by the theory of resonances in dynamical systems. In particular, the locked frequency forms a three-frequency resonance with the frequencies of the quasi-periodic input. The circuit is able to lock also in case of deterministic perturbation (additional frequency components) and stochastic perturbation (wide-band noise). The circuit is closely related to the pitch perception of complex sound in humans and, as such, can be considered a bio-inspired device. From the point of view of applications, it may be considered as an extension of the Phase Locked Loop (PLL) with the additional ability of locking simultaneously to more than one frequency. Due to the dynamical and structural robustness of the locked states, the Q-PLL represents a tangible advance for the development of specific applications, for example, in medicine (hearing aids, and cochlear implants), in robotics (artificial senses), and in industrial and consumer electronics (improvement of speech intelligibility, pitch-based processing, etc.).<br>

A new kind of locked circuit: the Quasi-Periodic Locked Loop (Q-PLL)

A new nonlinear circuit with frequency locking capability in the case of a generic quasi-periodic input, is presented. Due to this capability the circuit is called a Quasi-Periodic Locked Loop (Q-PLL). The locked frequency is parametrically selected from among those prescribed by the theory of resonances in dynamical systems. In particular, the locked frequency forms a three-frequency resonance with the frequencies of the quasi-periodic input. The circuit is able to lock also in case of deterministic perturbation (harmonics of the input frequencies) and stochastic perturbation (wide-band noise). The circuit is closely related to the pitch perception of complex sound in humans and, as such, can be considered a bio-inspired technology. From the point of view of applications, it may be considered as an extension of the Phase Locked Loop (PLL) with the additional ability of locking simultaneously to more than one frequency. Due to the dynamical and structural robustness of the locked states, the Q-PLL represents a tangible advance for the development of specific applications, for example, in medicine (hearing aids, and cochlear implants), in robotics (artificial senses), and in industrial and consumer electronics (improvement of speech intelligibility, pitch-based processing, etc.).

A new kind of locked circuit: the Quasi-Periodic Locked Loop (Q-PLL)

A new nonlinear circuit with frequency locking capability in the case of a generic quasi-periodic input, is presented. Due to this capability the circuit is called a Quasi-Periodic Locked Loop (Q-PLL). The locked frequency is parametrically selected from among those prescribed by the theory of resonances in dynamical systems. In particular, the locked frequency forms a three-frequency resonance with the frequencies of the quasi-periodic input. The circuit is able to lock also in case of deterministic perturbation (harmonics of the input frequencies) and stochastic perturbation (wide-band noise). The circuit is closely related to the pitch perception of complex sound in humans and, as such, can be considered a bio-inspired technology. From the point of view of applications, it may be considered as an extension of the Phase Locked Loop (PLL) with the additional ability of locking simultaneously to more than one frequency. Due to the dynamical and structural robustness of the locked states, the Q-PLL represents a tangible advance for the development of specific applications, for example, in medicine (hearing aids, and cochlear implants), in robotics (artificial senses), and in industrial and consumer electronics (improvement of speech intelligibility, pitch-based processing, etc.).

Complaints of People with Hyperacusis

Background Hyperacusis is a prevalent auditory disorder that causes significant distress and negatively affects quality of life for many patients. Patients with hyperacusis often have different complaints about the sounds and situations that they experience. Audiologists may have few patients with hyperacusis, and a limited understanding of the sounds and situations that are reported to be challenging by their patients. Purpose To investigate the common complaints reported by hyperacusis patients. Research design A qualitative study was conducted with 11 hyperacusis patients who participated in a group session. Results All 11 hyperacusis patients experienced negative reactions to specific sounds. In addition, many patients reported physical symptoms such as headaches, balance problems, dysosmia (strong smell problems), and light sensitivity. Sounds that induced discomfort were wide ranging and included low-frequency sounds, high-frequency sounds, wide-band noise, and sudden, high-intensity sounds. Most patients (9/11, 81.8%) reported negative reactions to music in loud rock concerts. Patients reported that stress/tension (90.9%) worsened their hyperacusis, while removing themselves from noise (90.9%) relieved their hyperacusis. Conclusion Loudness is only one of the many factors related to the discomfort of patients with hyperacusis. Across patients, we observed that there were different complaints about the sounds and situations that produced difficulty due to hyperacusis. Physical symptoms following sound exposure were also reported by the patients, suggesting that hyperacusis is a complex disorder and requires intervention that often involves multiple members of the medical team.

Analysis of jamming successfulness against RCIED activation with the emphasis on sweep jamming

In this paper we first briefly compare the performances of active jamming remote controlled improvised explosive devices activation using wide-band noise and frequency sweep signal. Frequency sweep is the most widely used technique intended for active jamming and we analyze its characteristics: 1) sweep speed, 2) conditions for certainly successful jamming, 3) successful jamming probability if jamming is not certainly successful, and 4) step of frequency change when frequency sweep is applied. The separate paper section is devoted to the successful jamming probability calculation in general. The attention is also paid to jamming probability determination when starting and ending sweep signal frequencies are varied. The initial research has been upgraded and extended. The presented results refer to jamming equipment development in IRITEL, but it is important to add that they are also applicable to the other similar jamming systems realizations.

A Broadband Beamformer Suitable for UUV to Detect the Tones Radiated from Marine Vessels

In this paper, the issue that the underwater unmanned vehicle (UUV) with a sonar array achieves the passive detection of vessel targets by detecting the tones radiated from the targets is considered. The multi-beam low-frequency analysis and recording method is widely applied in a manned sonar system. The sonar operator provides an auxiliary decision to extract the target tones from the multiple beams output. However, the complexity of the multi-dimensional information fusion makes it difficult to apply the multi-beam processing in the unmanned sonar system. Aiming at this problem, we introduce the self-adjusting characteristics of adaptive line enhancer to a time domain broadband beamformer and then propose a self-steering broadband beamformer. The proposed beamformer can adaptively steer the main beam to the direction-of-arrival (DOA) of the tonal target. There is no need to pre-form the multiple beams. The complexity of the UUV-based tone detection is reduced. Theoretical derivation and simulation experiments verify that the main beam of the proposed beamformer can track the DOA of tonal target which is rapidly changing. Meanwhile, the tonal interferences as well as the wide-band noise are well suppressed.