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An offset tone based gain stabilization technique for mixed-signal RF measurement systems

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Title An offset tone based gain stabilization technique for mixed-signal RF measurement systems
 
Creator JOSHI, G
MOTIWALA, PD
RANDALE, GD
SINGH, P
AGARWAL, V
KUMAR, G
 
Subject Offset tone
RE gain stabilization
RF instrumentation and control of accelerators
 
Description This paper describes a gain stabilization technique for a Rh signal measurement system. A sinusoidal signal of known amplitude, phase and close enough in frequency is added to the main, to be measured RF signal at the input of the analog section. The system stabilizes this offset tone in the digital domain, as it is sampled at the output of the analog section. This process generates a correction factor needed to stabilize the magnitude of the gain of the analog section for the main RF signal. With the help of a simple calibration procedure, the absolute amplitude of the main RE signal can be measured. The technique is especially suited for a system that processes signals around a single frequency, employs direct signal conversion into the digital domain, and processes subsequent steps in an FPGA. The inherent parallel signal processing in an FPGA-based implementation allows a real time stabilization of the gain. The effectiveness of the technique is derived from the fact, that the gain stabilization stamped to the main Rh signal measurement branch requires only a few components in the system to be inherently stable. A test setup, along with experimental results is presented from the field of Rh instrumentation for particle accelerators. Due to the availability of a phase synchronized Rh reference signal in these systems, the measured phase difference between the main Rh and the RE reference is also stabilized using this technique. A scheme of the signal processing is presented, where a moving average filter has been used to filter out not only the unwanted frequencies, but also to separate the main RF signal from the offset tone signal. This is achieved by a suitable choice of sampling and offset tone frequencies. The presented signal processing scheme is suitable to a variety of RE measurement applications. (C) 2015 Elsevier B.V. All rights reserved.
 
Publisher ELSEVIER SCIENCE BV
 
Date 2016-01-15T04:46:58Z
2016-01-15T04:46:58Z
2015
 
Type Article
 
Identifier NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, 795,399-408
0168-9002
1872-9576
http://dx.doi.org/10.1016/j.nima.2015.06.015
http://dspace.library.iitb.ac.in/jspui/handle/100/17794
 
Language en