Introduction

As the most important high technology national strategic field in the twenty-first century, earth observation consists of two elements, one is the physical and chemical characteristics of the observed object (What), namely remote sensing: the other is four-dimensional time and space, namely navigation and position (Where, When). Thus, navigation is an old and young science. Before the appearance of satellite position systems, radio navigation systems were mainly used for remote navigation and position. Radio navigation position has played a very important role in the history of navigation through methods such as Roland-C, Omega and Doppler systems. However, it covers a small working area. This has largely limited its development and application, because radio wave propagation is affected by the atmosphere, the position accuracy and other factors. It was not until the development of global navigation position in the 1990s, which can provide continuous and high-precision three-dimensional position velocity and time information to users at sea, on land, in air and space in around the clock on a global scale and can lead to epoch-making changes in the navigation and position of carriers such as ships, aircraft and automobiles. However, globle position system also has some shortcomings, such as satellite signals which are susceptible to be interfered, poor reception in hidden areas, no in-water capability, and some difficulty in underwater position. And being controlled by the military of the country where the system is located, the application can be very limited at critical times. On the other hand, although the instantaneous position accuracy of inertial navigation system is high, the error will accumulate over time. Based on this consideration, it is particularly important to study new technologies for independent navigation and position in environments where satellite signals do not cover or are subject to electromagnetic interference. This monograph is the mathematical-physical basis of passive navigation and positioning based on natural vector fields as the main source.