Dual-tracking multi-constellation GNSS front-end for high-performance receiver applications

This paper presents the design and implementation of a dual–tracking Radio Frequency (RF) front–end for a multi–constellation Global Navigation Satellite Systems (GNSS) receiver. The RF frond–end is based on the direct RF conversion architecture, which employs sub–Nyquist sampling (also known as subsampling) at RF. The dual–tracking RF front–end is composed of a few RF components that are duplicated to form the two RF channels. Employing a dual–channel Analogue–to–Digital Converter (ADC) enables synchronisation of the RF channels and minimises the errors resulting from the differences in the satellite clocks and the propagation delay between the two RF channels. The digitised GNSS signals are processed by two separate acquisition and tracking engines that are driven by the front–end’s master clock. This setup provides two synchronised receivers that are integrated onto one piece of hardware. The hardware is intended to be used for research applications such as multipath mitigation, scintillation assessment, and advanced satellite clock and spatial frame transformation modelling.

NFC RF Analog Challenge and Enhanced High Speed Transmitter Design

This paper investigates the inherent radio frequency analog challenges associated with near field communication systems. Furthermore, the paper presents a digital based sigma-delta modulator for near field communication transmitter implementations. The proposed digital transmitter architecture is designed to best support data intensive applications requiring higher data rates and complex modulation schemes. An NFC transmitter based on a single-bit sigma-delta DAC is introduced, and then the multi-bit extension with necessary simulation results are presented to confirm the suitability of the architecture for near field communication high speed applications.