To investigate the accuracy of the determination of terrestrial refraction from reciprocal zenith angles and astronomical latitudes and longitudes at both ends of a line a test net with lines from 4 km to 23 km was observed and three dimensionally adjusted. As the measurements of the zenith angles were repeated every hour 40 times in an average the adjusted values were taken as a substitute for the true values. It is shown, that the mean refraction coefficient k, which is changing from k = 0.10 at day up to k = 0.34 at night, and the corresponding refraction angle can be determined very accurately, if both angles are measured simultaneously. Observations with day light are better than observations in the night. For observations with day light the mean difference between the true refraction angle at the observation station and the mean refraction angle of the observed line was smaller than ± 1″ independent of the length of the line. That means that the mean deviation of the true effective refraction coefficient in the observation station and the mean refraction coefficient of the observed line was inverse proportional to the distance.
For the integration of different navigational aids of an aircraft by a general purpose computer the following way is proposed: The basic navigational system is a doppler or inertial dead reckoning system (D.R.S.). The other navigational aids serve for control measurements, with the help of which the error of the D.R.-position and the most important systematic error sources of the D.R.S. are determined by least square adjustment during flight. These error quantities are then used for a corresponding correction of the D.R.S. The supplementary navigational aids are consequently used both for the correction of the D.R. position and for the calibration of the D.R.S. The method is described for the example of the integration of a doppler D.R.S. with Tacan.From the great number of different navigational aids, which are today available or in development, we can draw the conclusion that none of these navigational systems can satisfy all requirements. Therefore, for many years it has been the custom to combine several navigational aids, and thus the human navigator has the task of evaluating the different navigational information. This evaluation is, however, often disturbed by unfavourable conditions. In a high-speed aircraft for example the navigator is overburdened by a lack of time and space, errors in the navigational sensors, &c. This necessarily means that the evaluation of the data is reduced to a minimum, and that a great deal of the available information is lost.
Each navigational aid has its advantages and disadvantages and for that reason the optimum aid will be a combination of several aids. The best way of combining the aids seems to be by means of an automatic dead reckoning computer which continuously computes position from true air-speed and wind-speed and other data which can be fed into the existing navigational aids by means of a data transformer. Data from the integrated system can be transmitted by data link to air traffic control to correct the flight programme, &c. This paper, which was presented at Dusseldorf at the German Navigation Society's meeting (5–7 June 1962), surveys the field of integrated navigation systems and describes a number of possibilities. Formulae are derived for the accuracy of Vortac and D.R. and Vortac and doppler. It is published with the kind permission of the German Navigation Society.If we look critically at the navigational aids which are available today we find that all have advantages and disadvantages, and that no one aid can be claimed to be suitable for all purposes. This situation will still exist for many years. Therefore it seems very advantageous to combine the available navigational aids to form an integrated navigation system in such a way that the possibilities may be fully utilized.
Dr. Ramsayer's paper, presented at the tripartite meeting on automatic navigation held in Paris last April, describes a dead-reckoning computer on which position is presented instantaneously on a map.The so called Automatische Koppelkarte has been developed by the Institute of Air Navigation of the Technical University of Stuttgart, and is a new type of dead reckoning computer differing from the usual navigation computers in that position is immediately indicated on a map; there are many possibilities for combining the device with other navigational aids.Fig. 1 shows a schematic diagram of the computer. It consists of the computer, the map display and the course and track indicator. The station selector and the coordinate transformer shown in Fig. 1 are additional units, only used when monitoring by tacan is desired, as will be described. The computer is fed by a gyro-magnetic compass and a true airspeed transmitter. The wind is set at the map display, and ‘grivation’ at the course and track indicator. From these data both the flight path and the track are computed. The flight path is resolved in two rectangular components and is displayed by a light pointer on a map of conformal conical projection. The standard parallels of the map are selected in such a way that the distortion in length is practically negligible for the area of interest.
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