Estimation and Analysis of Instrumental Biases for GPS and NavIC Satellites and Receivers

Abstract

The positional accuracy of Global Positioning System (GPS) and Navigation with Indian Constellation (NavIC) are affected by errors, one of the predominant errors is instrumental delay. This delay distorts the satellite signal and effect the position accuracy. To counter this problem, efficient models shall be used. In this paper, satellites' and receivers' instrumental bias is estimated using a modified Fitted Receiver Bias (FRB) method, Singular Value Decomposition (SVD) technique and Self-Calibration of Pseudo Range Error (SCORE) model. The FRB method is based on the minimization of standard deviation of vertical Total Electron Content (TEC) computed from different satellites. The SVD based Least Mean Square (LMS) algorithm uses the values of one-day period corresponding to four GPS and NavIC stations. It uses data from dual frequency GPS receivers. To derive the instrumental bias errors the SCORE technique uses a self-consistency constraint on the receiver's measurements of ionospheric delay.

Estimates of the Carrier Frequency of the Signal received by the Satellite Communication system in Package mode

“…On-demand satellite communication systems (OCS), which operate with frequency division multiplexing (MAFD -OCS), operate at fairly low information rates. As a result, in such systems it is possible to use relatively cheap satellite terminals with a small aperture class a VSAT (very small aperture terminal) [3,4]. Relatively narrowband channels are used in MAFD -OCS systems.…”

“…Earth stations of the system, built on the technology of MAFD -OCS, include modems of information channels and modems that form a common control channel. This control channel in satellite communication systems with the provision of the channel on demand is called a common synchronization channel (CSC) [2,3,4]. Modems that provide CSC on peripheral earth stations operate in continuous mode for reception and in batch mode for transmission.…”

“…In other words, there is a common packet control channel in MAFD -OCS satellite systems. This channel is usually built on the algorithm ALOXA with random access of packets [1,4]. To ensure the operation of modems, signal demodulators are used, which should be distinguished by types: demodulators operating in batch mode and demodulators operating in continuous mode.…”

“…In the presence of information about the parameters ( d ,  ,  ) MP-estimation of the carrier frequency can provide the minimum limiting variance, which will be determined by the lower Kramer-Rao boundary [4,5]. At large observation intervals ( 1  K ), the normalized Kramer-Rao boundary for estimating the carrier frequency of the phase-modulated signal can be represented as a functional dependence on the unit signal pulse ( ES ), the interval of information pulses of the complex envelope of the received signal ( N 0 ) and the interval on which the estimation is performed.…”

Consideration of limitations, which are formed by the input signal, on the phase error minimization process during carrier frequency tracking system of synchronization of radio technical device of communication

“…The vast majority of systems use high-precision encoding with Viterbo decoding and cascading codes. Widespread are turbo codes and codes with low density of parity checks [22,23]. It should be noted that in general, when receiving the input signal by the synchronization system, the actual problem is to reduce the effect of noise interference in order to increase the signal-to-noise ratio (SNR).…”