Adaptive digital receivers for analog front-end mismatch correction

Phase and gain mismatches between the I and Q analog signal processing paths of a quadrature receiver are responsible for the generation of image signals which limit the dynamic range of a practical receiver. In this paper we analyse the effects these mismatches and propose a low-complexity blind adaptive algorithm to minimize this problem. The proposed solution is based on two, 2-tap adaptive filters, arranged in Adaptive Noise Canceller (ANC) set-up. The algorithm lends itself to efficient real-time implementation with minimal increase in modulator complexity.

Adaptive compensation of analog front-end I/Q mismatches in digital receivers

I and Q Channel phase and gain misniatches are of great concern in communications receiver design. In this paper we analyse the effects of I and Q channel mismatches and propose a low-complexity blind adaptive algorithm to minimize this problem. The proposed solution consists of two, 2-tap adaptive filters, arranged in Adaptive Noise Canceller (ANC) set-up, with the output of one cross-fed to the input of the other. The system works as a de-correlator eliminating I and Q mismatch errors.

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.

The British Army of the Rhine: Turning Nazi Enemies into Cold War Partners

Between 1945 and 1957, West Germany made a dizzying pivot from Nazi bastion to Britain's Cold War ally against the Soviet Union. Successive London governments, though faced with bitter public and military opposition, tasked the British Army of the Rhine (BAOR) to serve as a protecting force while strengthening West German integration into the Western defense structure. Peter Speiser charts the BAOR's fraught transformation from occupier to ally by looking at the charged nexus where British troops and their families interacted with Germany's civilian population. Examining the relationship on many levels, Speiser ranges from how British mass media representations of Germany influenced BAOR troops to initiatives taken by the Army to improve relations. He also weighs German perceptions, surveying clashes between soldiers and civilians and comparing the popularity of the British services with that of the other occupying powers. As Speiser shows, the BAOR's presence did not improve the relationship between British servicemen and the German populace, but it did prevent further deterioration during a crucial and dangerous period of the early Cold War. An incisive look at an under-researched episode, The British Army of the Rhine sheds new light on Anglo-German diplomatic, political, and social relations after 1945, and evaluates their impact on the wider context of European integration in the postwar era.