Abstract: The navigation apparatus gives, to a map match processing portion, the measured present location and progress bearing of the vehicle with the use of the position bearing measuring portion for each predetermined period. The map match processing portion reads out the road data about the road close to the measured present position from the memory apparatus to effect the map match processing with respect to each link in accordance with the road data for correcting the measured present position. The correcting operation is effected only when the frequency, where the similarity degree with respect to the measured present position and progress bearing at this time is judged to be larger than the predetermined threshold value, is larger than the predetermined constant Ck. The road data are visually displayed on the visual displaying region of the displaying apparatus. The predetermined diagrams are displayed in a superimposed manner, in the corrected present position, on the road data visually displayed.

Abstract: A processing apparatus within a navigation system comprises a track calculating portion for subsequently memorizing a bearing detected by a bearing sensor to calculate a track, and a map match processing portion for performing the map matching process. A position correcting portion corrects a vehicle position onto a road in accordance with road data 35 by the map match processing portion 34. The bearing correction is not effected when the bearing difference conditions are established although a bearing correcting portion 39 corrects the bearing showing the progressive direction of the vehicle into the link bearing of the road. The bearing difference condition is a condition where the bearing difference between the link bearing and the bearing showing the progressive direction of the vehicle is large, and there is a possibility of further increasing the error when the error of the bearing showing the progressive direction of the vehicle is large and the correction is effected in the link bearing.

Abstract: A computing method of floating-point represented data including dividing data x with a n (n>M) bit length into high rank data X' and low rank data .alpha. with a mutual m bit length, a mantissa part of the high rank data X' leaving the same bits as those of the data x by k bits (k.gtoreq.1) from its initial bit to replace the rest of the bits of X' by zero, the low rank data .alpha. being formed as X--X', and computing other data together with the high rank data X' and the low rank data .alpha..

Abstract: The delta-sigma modulator includes a secondary delta-sigma modulator which carries out a secondary delta-sigma modulation for an analog input signal, thereby producing a first quantization signal. A quantization noise extractor extracts a quantization noise occurring in the secondary delta-sigma modulator. A primary delta-sigma modulator carries out a first delta-sigma modulator for the quantization noise, thereby producing a second quantization signal. A differentiating circuit differentiates the second quantization signal supplied from the primary delta-sigma modulator. An adder adds the first quantization signal and an output signal of the differentiating circuit, thereby producing a digital output signal corresponding to the analog input signal.