Group delay of a signal in the receiving path estimation of measuring devices with the use of the step response

Abstract

The current parameters coordinate-time measuring instruments calibration methods of global navigation satellite systems are considered. For coordinate-time measuring instruments calibration in the process of their development and testing, the global navigation satellite systems signals simulators are used. However, the simulators also need a calibration procedure. Currently, there are various methods for ensuring the metrological characteristics of simulators, including their calibration using oscilloscope. However, this method has not only advantages, but also limitations related to the use of an oscilloscope. VNIIFTRI develops a new reference measuring device – the calibrator of the global navigation satellite systems simulator. Since the work of the calibrator is based on the same principles as the work of the navigation receiver and the calibrator determine the time delay of accepted signal from the calibrated simulator, it is extremely important to accurately evaluate the own group time delay of the calibrator by the reception circuit and develop the methodology of determining the determination this metrological characteristic. The schematic solutions used of creating a calibrator include digital blocks, such as digital-analog or analog-cyphrane converters. The purpose of the study is to evaluate the group time delay in the input circuit of the calibrator containing an analog-digital converter. Traditional group delay estimation methods using S-parameters are not suitable for this purpose because they cannot compare analog and digital signals. This article has developed an indirect method for assessing the grouping time delay in the calibrator input circuit. The method proposed by the authors determines the group time delay time in the reception of the calibrator according to the circuit transition characteristic. The method is verification and calibration of measuring equipment using the input and output signals with an analog-digital converting. Using the proposed method, the group time delay in the calibrator circuit containing an analog-digital converter is estimated. The results of studies are given by the proposed method of this parameter of circuits with various microwave devices (power splitter, circulator). The proposed method allows you to obtain accurate assessments of the frequency characteristics of the measuring devices circuits and normalize their metrological characteristics.