Reliable NCO carrier generators for GPS receivers

Abstract

Four strategies for upset protection in NCO (Numerically controlled oscillator) generators are presented and compared in this paper 1. This work is motivated by the increased prevalence of single event upsets due to process/voltage/temperature variations coupled with the increased advancement of CMOS technology. The occurrence of these upsets in the GPS context (the system under the test in this paper) can lead to a loss of the GPS signal tracking, then the corresponding satellite signal must be re-acquired resulting in high energy expenditure and time delay. It can result also in a corrupted position given by the GPS receiver. Results of experiment using a GPS receiver design are presented in this paper to evaluate the performance of proposed methods. This work can be extended and generated to any system using feedback loops information.

Demo: Localisation in a faulty digital GPS receiver

“…Position given by a noiseless GPS receiver X(t) (color orange), by a faulty GPS receiver without adding the fault tolerant technique (color red), by a faulty GPS receiver when using the fault tolerant technique (color blue), displayed using Google earth in order to have a complete GPS receiver (Radio Frequency and digital processes). Although, fault tolerant techniques that have been proposed in [5], [6] and [7] to protect, respectively, the Gold code generator, the the Numerically Controlled Oscillator and the correlation will be implemented in the noisy receiver to evaluate the robustness of the complete GPS receiver against transient errors. An ASIC will replace the FPGA target once the study of the trade-off between the complexity and the performance of the GPS receiver is achieved.…”

Improving the Performance of the Carrier Tracking Loop for GPS Receivers in Presence of Transient Errors due to PVT Variations

“…GPS receivers are widely used in mobile context, and there is motivation to minimise power consumption and maximise battery life in these devices. In [10] and [11], strategies have been proposed and evaluated for upset protection in the Gold sequence generators and the Numerically Controlled Oscillator (NCO) respectively. The authors of [12] presents two approaches to deal with internal logic upsets inside correlation process used in the tracking process of GPS receivers.…”