Since its discovery by Isidor Rabi in 1938 and his subsequent Nobel Prize in physics in 1944, scientists have been using nuclear magnetic resonance (NMR) technologies as a tool in analytic chemistry, biochemistry, and the study of atomic interactions. In 1952 General Electric proposed that a gyro could be made based on NMR technology, in particular the concept of using the intrinsic quantum property of spin was of interest, specifically the stability of a quantized angular momentum of a nucleus when subjected to a stable magnetic field. From roughly 1952 to 1980 several groups worked on the concept and development of an NMR based gyro, with some being more successful than others. While the fundamentals of the technology were understood and the concept demonstrated, the enabling technologies required to develop a compact, robust design that would operate outside of the controlled laboratory environment were not available. For the past several years Northrop Grumman has been investigating and developing a NMR-Gyro. Owing to the advancement in enabling technologies a small robust gyro package can now be produced. The current micro-NMRG design is housed in a 10 cubic centimeter package and has been tested over a limited environment. Projected size estimate for a 6 degree-of-freedom inertial measurement unit is on the order of 300cc with a power draw of a few watts. Initial testing of the unit has shown a performance level better than any MEMS de-vice currently available as well as approaching the performance of many fiber optic gyros. The micro-NMR-Gyro has the potential to provide the end user a high-performance device in a small robust package. Presented in this paper is a summary of the basic principles of operation and performance testing results of the hardware to date.

At present time fiber-optic gyroscopes (FOGs) with closed-loop feedback scheme of operation are becoming widely used in inertial navigation systems. In the current work the series of devices developed and produced by LLC RPC “Optolink” are discussed. The first group is single-axis fiber-optic gyroscopes (FOGs) with differ-ent fiber length and fiber coil diameter: SRS-2000, SRS-1000, SRS-501, SRS-200. The second group comprises three-axis devices (TRS) and inertial measurement units (IMUs): TRS-500, IMU-500, IMU-501. All FOGs are producted in a so-called “minimal” configuration. The major components of FOGs and their impact on FOGs accuracy characteristics are discussed.

A new air-sea gravimeter, the next-generation successor to the Chekan gravimetric systems designed at Concern CSRI Elektropribor, JSC, is presented in this paper. The advanced constructions of the gravity sensor and gyro stabilization system of the gravimeter are considered. The design features of the new system are discussed: it is for the first time that all peripherals are included in the gyrostabilizer. The real-time program and postprocessing software are described. Comprehensive tests of the prototype gravimeter have shown a significant gain in accuracy as compared with the predecessor. The test results are presented.

Advanced road safety automotive applications require reliable (available) and robust (e.g. GNSS outages) position, velocity and heading information. The velocity information generated by a GNSS receiver, in general, is affected by less errors then the further generated position and ranges. Determination of the measurement weighting for the range information is not in all cases appropriate. Unidentified multipath effects may reduce the quality but do not affect the signal to noise ratio. This paper explores the concept of a segmented Kalman navigation for a vehicle navigation filter which fuses automotive onboard sensor data. A position filter providing only position information and a dynamic filter covering velocity and sensor error information are implemented in this approach. The dynamic filter is only aided by velocity information provided either by odometer or GNSS. The position filter is aided by the GNSS range information. The evaluation covers the processing of simulated sensor data and the usage of real time automotive sensor data recorded in scenarios with reduced GNSS quality in Key words: tightly coupled, gnss, inertial, segmented kalman filter, vehicle localization urban area.

A magnetometer is often used to aid heading estimation of a low-cost Inertial Pe-destrian Navigation System (IPNS) without which, the latter will not be able to ac-curately estimate heading for more than a few seconds, even with the help of Zero Velocity Update (ZVU). Heading measurements from the magnetometer are typi-cally integrated with gyros heading in an estimation filter – such as the Kalman Filter (KF) – to best estimate the true IPNS heading, resulting in a greater position-ing accuracy. When carried out indoors however, the reliability of these measure-ments are often questionable because of the magnetic disturbances that can disrupt the measurements. To solve this, a filtering method is often used to select the best measurements. However, the importance of the frequency of these measurement updates has not been highlighted.

In this paper, the impact of frequency of updates of a magnetometer to the overall accuracy of the navigation system is presented. The paper starts by discussing the use of a magnetometer in a low-cost IPNS. An exemplary filter to extract reliable heading measurements from the magnetometer is then described. From real field trial results, it will be shown that even if reliable heading measurements may be obtained indoors, it is still insufficient to increase the positioning accuracy of the low-cost IPNS unless it is reliable on every epoch.

A kind of marine strapdown attitude and heading reference system (AHRS) based on the principle of strapdown inertial navigation system (INS) is discussed here. With an electromagnetic (EM) log aided, the oscillations included in the attitude and heading errors are bounded by damping network. Furthermore, in order to de-crease attitude and heading errors aroused by EM log measurements, we introduce an adaptive network-based fuzzy inference system to control the damping ratio automatically in terms of the vessel maneuvers conditions. The results of test dem-onstrate the validity of proposed method.

This paper continues the study [1] devoted to methods of GNSS signal search applied in space-based receivers. In Part 1, a combined approach is proposed, where the most effective search type is selected automatically based on a priori Doppler frequency. Here, a method to calculate the parameters of combined search is described. Calculation of probabilities of the first and second type errors for truncated Wald analysis is given in appendix to this paper.

The paper deals with the problem of the Earth remote sensing satellites attitude control with geometrically composite routes scanning (in the push broom mode) subject to the optoelectronic sensing equipment retargeting. The optimization problem of a control pattern as an construction elementary operation of the integrated control programs for Earth remote sensing satellites' multicircuit flight intervals is formulated. It is given a pattern's model. A pattern consists of a sequence of the spacecraft's attitude control maneuvers - retargeting and scanning. The problem of the optimal spacecraft attitude control for the retargeting maneuver is solved as one of optimization problems for such pattern. It is proposed a method to solve it, including conjugation of control programs for the pattern maneuvers.

The paper analyzes the long-term operational experience with the Chekan-AM gravimeter intended to solve various geophysical problems. Specific features of the Chekan-AM operation aboard seismic vessels and aircraft are considered. The factors affecting the null-point drift rate stability of the gravimeter and some procedures for its refinement are discussed. A number of additional technical requirements have been formulated, aimed at improving the accuracy of gravimetric measurements. These requirements are supposed to be implemented in a new air-sea gravimeter of the Chekan type.