Vehicle automation and cooperation is progressively being introduced in traffic networks. As a consequence research to assess its impacts is currently on-going. Adaptive Cruise Control (ACC) is one of the first automated functionalities available for privately owned vehicles. An experimental study has been conducted to investigate the key features of the ACC controller using Global Navigation Satellite System data. The first remarks based on the data focus on the controller's reaction time and desired time gap. Both parameters are essential in order to assess the influence of these technologies to safety and traffic flow. It is a common assumption that autonomous vehicles will have negligible reaction time and desired time gap comparable to that of a human driver. This paper presents an experimental study of an ACC-enabled vehicle on car following mode and a methodology for the estimation of the controller's reaction time that can be used as benchmark in other scenarios. The results show the reaction time to be around l.ls and the time gap to be distinctly larger than that of a human driver. This poses concern on the impact of ACC on traffic flow when a significant number of vehicles will have such systems operating on-board.

Adaptive notch filters have been the focus of intense research for more than three decades. Low computational requirements and good performance make them attractive for tracking frequency modulated signals. Despite the extensive literature on adaptive notch filters, algorithm extensions and new models for describing the dynamics of the notch frequency continue to be proposed. In this study, the equivalence between adaptive notch filters using a plain gradient (PG) algorithm and frequency lock loops (FLLs) with exponential filtering is established. FLL theory is then used to analyse the noise performance and signal tracking capabilities of adaptive notch filters. A linear model describing the dynamics of the filter adaptation process is derived and the concepts of loop and Doppler bandwidths are introduced. Criteria based on the loop and Doppler bandwidths are suggested to set the PG adaptation step. Finally, algorithm extensions based on the FLL theory are proposed. Theoretical results are supported by Monte Carlo simulations which show the validity of the analysis performed.

Jamming is the act of intentionally directing powerful electromagnetic waves toward a victim receiver with the ultimate goal of denying its operations. This paper describes the main types of Global Navigation Satellite System (GNSS) jammers and reviews their impact on GNSS receivers. A survey of state-of-the-art methods for jamming detection is also provided. Different detection approaches are investigated with respect to the receiver stage where they can be implemented.

Pulsed interference can severely degrade the performance of a GNSS receiver. For this reason, several mitigation techniques have been developed for reducing the impact of disturbing signals. Among the different pulsed interference mitigation techniques, pulse blanking (PB) has received particular attention due to its simplicity and effectiveness. In this study, the performance of PB is assessed in the presence of signal conditioning and the impact of front–end parameters, such as the number of bits used for quantisation and the gain of the automatic gain control (AGC), is analysed. The theoretical analysis is supported by Monte Carlo simulations and experimental results, which show that signal conditioning plays a fundamental role in the design of interference mitigation techniques.

Pseudolites are a technology with the potential of bridging the gap between outdoor and indoor navigation. Despite their potential, pseudolites can cause severe interference problems with non-participating receivers, i.e., devices not designed to exploit this technology. In this paper, the loss caused by pulsed pseudolite signals is determined as a function of the pulse duty cycle and the number of bits employed for signal quantization. Quantization, blanking and noise increase are identified as the main sources of signal degradation. Theoretical results are validated by simulations and experiments performed using commercial GPS receivers. The good agreement between theoretical and experimental results supports the validity of the proposed approach.

Due to the capability of GPS to provide an accurate and stable long-term reference, the use of a GPS receiver as an acceleration sensor has gained an increasing research interest. GPS-derived acceleration information is determined using Doppler rate measurements that are directly estimated from the output of a Frequency Lock Loop (FLL) or obtained by double-differentiating the carrier phase observations produced by a Phase Lock Loop (PLL). This paper presents a complete theoretical model allowing the evaluation of the Doppler rate accuracy and relating the variance of Doppler rate measurements to the Carrier-to-Noise density power ratio (C/N0) and the receiver architecture. Both standard and High Sensitivity (HS) receiver architectures are considered and the developed theoretical model is validated using live GPS data. Empirical results are compared against the developed theoretical model and, in all cases, a good agreement between empirical and theoretical results is observed.

New GNSS signals are usually characterized by the presence of secondary codes and high data rates that can make the sign of the transmitted signal change each primary code period. Therefore, in order to extend the coherent integration time, relative signs between subsequent portions of the incoming signal have to be estimated and used to remove the effect of sign transitions. In this paper the problem of testing all the possible sign combinations is addressed and efficient FFT-based algorithms, suitable for different situations, are proposed. The algorithms proposed take advantage of the structure imposed by secondary codes and the case of composite GNSS signals, made up of data and pilot channels, is considered. Preliminary results based on live E5a GIOVE-A data are also shown.