The Partial Shunt Regulator (PSR), which is the typical power regulator of spacecraft, is modeled. To realize a simple structure, the voltage source of the PSR controller is identical to the output voltage of the PSR. However, small signal model structure of the PSR is very complex, because the PSR has a main feedback control loop as well as two additional coupled loops. The complex structure of model is simplified to a more meaningful structure, which has only a main feedback loop. The proposed PSR structure is verified by comparing the analysis of the model with SPICE simulation of the PSR circuit.
The third-generation Korean sounding rocket, KSR-III, was successfully launched on Nov. 28, 2002 from the western coastal area of the Korean Peninsula. The previous KSR-I and -II series had employed a solid propulsion system whereas the KSR-III utilizes Korea's first liquid propulsion system. The prime objective of the mission was to evaluate the performance of the liquid propulsion system. The onboard electronics system of the KSR-III is an enhanced version of the ones used in the previous series. The system has extended data channels and has adopted a distributed data processing system using the RS-485 bus network. The rocket has various sensors to measure physical characteristics such as temperature, pressure, strain, acceleration, etc., and has scientific instruments including an ozone detector and two magnetometers. The flight data is transmitted to the ground station in real time by the onboard telemetry system. The onboard electronics system of the KSR-III mainly consists of telemetry, an RF subsystem, a tele-command system, a power supply system, and scientific payloads. Herein, we present an overview of the enhanced electronics system of the KSR-III and representative flight test results analyses including scientific data are discussed.
An adaptive impedance tuning circuit (AITC) is used to compensate for the impedance between the arbitrary load impedance and the characteristic impedance of interest. An AITC is required for correct and accurate load impedance measurements. A new type of mismatch measurement circuit that measures the arbitrary load impedance more accurately is proposed and its performance against existing methods is compared. The proposed circuit exhibits a significant performance improvement compared with the conventional method, and it could be applied to different communication systems that have a variety of input signal strengths.Introduction: In an electrical system, maximum power transfer between a load and a source is achieved when impedances of the load and the source are matched with respect to each other, which minimises reflection losses between the load and the source. In RF communication, the characteristic impedance of the front end is substantially constant, but the antenna impedance varies considerably with frequency and external circumstances. One way to solve this problem is to use an adaptive matching circuit instead of a fixed matching circuit. To correctly apply an adaptive impedance tuning circuit (AITC), accurate measurement of the load impedance is required. To respond rapidly to the continuously changing circumstances, a method for calculating the load impedance directly without iteration is a more efficient way than a method with iterations [1]. This Letter details a load impedance measurement method using a sectioned λ/4 transmission line (TL) without iterative calculations. The sectioned-TL-based method and theory has been presented in several papers [2,3]. According to [2], the TL should be divided into several parts, and each part must be measured, so this technique requires complex calculations. In addition, this technique is difficult to implement. The technique in [3] is simplified to a three-point measurement on a λ/4 TL; however, the calculation method for selecting the exact results is not presented.This Letter presents a calculation method for directly measuring the load impedance by only measuring the voltages at three points on the λ/4 TL without iteration, and suggests a selection algorithm for determining the exact measurement values from several calculated load impedances. In addition, a new type of mismatch measurement circuit is proposed. This novel circuit measures the arbitrary load impedance more accurately by using a high-impedance sampling TL and sampling capacitors. By comparing the performance with the conventional method that uses coupling resistors, the superior performance of the proposed circuit is demonstrated.
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