Tushar Saxena al. International Journal of Research Aspects of Engineering and Management ISSN: 2348-6627, Vol. 1, Issue 1, FEB 2014, pp. 1-3 © 2014 IJRAEM All Rights Reserved 1 A Literature Study of Various Satellite Navigation Systems with Reference to Their Signaling Scheme Tushar Saxena 1 , Deepak Kumar 2 , J.S.Jadon 3 1 Student, M. Tech, AITEM, Amity University, Noida 2 Asst. Prof. Dept. of ECE, E-Max group of Institutions, Badhauli, Ambala. 3 Asst. Prof., AITEM, Amity University, Noida. Abstract —The concept of satellite navigation has started from 1973 with the very first introduction of GPS, as the time passes; in 1995 GPS navigation system becomes the very first global navigation system. There are various other systems for navigation, some are global navigation systems and some are regional navigation systems. This paper presents a literature study on various navigation systems and the signal scheme and modulation format which evolves through the time with special description for IRNSS Keywords— GPS, IRNSS, Galileo, QZSS, Compass, BPSK, BOC, MBOC I. INTRODUCTION In 1970s US military’s Department of Defense (DOD) brings the concept of satellite navigation system. In the mid of 1990s, they started the world’s first navigation system known as the global navigation system. For a long time there hadn’t been any other navigation systemavailable, but recently in 2010 Russia has launched their GLONASS global navigation system and the only other alternative for GPS. With the advancement in technology and need of positioning and tracking services of civil users various other countries has joined the race for their navigation system. Some systems are the global systems and some become regional navigation systems i.e. monitoring, tracking only a particular geographical region [1]. The different navigation systems available or in talks today are USA’s GPS, Russia’s GLONASS, Europe’s Galileo Navigation System, India’s IRNSS, Japan’s QZSS, China’s Compass [2][3]. In the later sections, we will discuss these navigation systems and their signaling structure in detail. II. GLOBAL POSITIONING SYSTEM In 1973, the development of GPS systems began with the aim to empower the military operations. Requirements for developing the GPS systems from thesignaling point of view are as follows [2]: - Multiple access capabilities so that no interference in the GPS signals from other satellites should take place. - Avoiding some amount of multipath interference. - Minimization of interference from jamming, spoofing of signal etc up to a certain level. - Low power signal so that it should not interfere with the microwave line of sight communication signals. So, there requirements were fulfilled by using DS-SS (Direct Sequence Spread Spectrum) implementation of CDMA as it can distinguish signals from other satellites as well. Also BPSK modulation is used in NRZ format which gives simple signal structure possessing a constant envelope and can be easily transmitted with High Performance Amplifiers as used by GPS satellite transmitters [2]. The system uses 3 signals, 2 high performance signals with long spreading codes and fast code rates and is known as P or Precise spreading codes broadcasting in L1 and L2 bands at the frequency range 1575.42 MHz and 1227.6 MHz respectively. These P codes are encoded by classified Y codes so that unauthorized users cannot access the signal. Recently P codes signals are replaced by M codes signals which are used in military purposes as they provide much better jamming resistance, authentication and confidentiality. The third signal is known as Coarse/Acquisition signals, transmitting on L1 band and is not encoded or encrypted. This is the signals civil users use for their tracking and positioning services. GPS signals uses CDMA Gold codes of 1023 bit, it provides good correlation properties with the code rate of 1.023 MHz For M codes, GPS now uses BOC modulation scheme in L1 and L2 bands both and M BOC modulation in time multiplexed fashion in L1C band [2][3]. III. GLONASS The Russian navigation system, GLONASS as an acronym of Global Navigation Satellite System is operated by Russian federation govt. by Russian space forces. The ground segment of Glonass located within the former Soviet Union territory which results in inferior performance in the stability and predictability as compare to GPS where the ground segment is spreaded all over the world. GLONASS uses FDMA or frequency Division Multiple Access to transmit its signal. This allows two GLONASS Satellites to transmit their navigation system at their own carrier frequency. It uses BPSK modulation scheme for C/A and P codes at L1 band, L3 band and L2 band all [4]. GLONASS satellite transmitstwo different types of signals: Standard Precision (SP) and High Precision (HP) in both the L1 and L2 bands. The GLONASS standard accuracy signal, also known as C/A Code with the clock rate 0.511 MHz and is designed for use by civil users worldwide while the high accuracy signal [5]. (P Code) has a clock rate of 5.11 MHz which is onlyavailable to users authorized by the Ministry of Defense.