Data processing: measuring – calibrating – or testing – Measurement system – Speed
Patent
1998-09-14
2000-11-07
Shah, Kamini
Data processing: measuring, calibrating, or testing
Measurement system
Speed
701 70, 701213, 701214, 342357, 342386, G01S 502, H04B 7185
Patent
active
06144927&
DESCRIPTION:
BRIEF SUMMARY
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to a data transmission device for motor vehicles, comprising a pulse generator and a monitoring unit, as well as a pulse generator for the monitoring unit.
Pulse generators are customarily introduced into a vehicle transmission and, by the detection as a function of time of the change between tooth and tooth-gap of a rotating gear wheel, generate an electric signal which is modulated in proportion to the speed of the vehicle. This signal is fed to a monitoring unit for recording and evaluation, the monitoring unit being developed in road traffic, for instance, as recording speedometer, taximeter, log or similar device.
Such pulse generators generally have, in addition to the sensor element, a circuit arrangement for the processing of a first signal and a signal driver in order to prepare the signal detected by the sensor element, which is initially still subject to numerous disturbing influences, for the feeding thereof by wire to the monitoring unit in the rough environment of a motor vehicle. The supplying of current to electronics of the pulse generator is generally effected in this connection from the monitoring unit over electric connecting lines.
In the event that the monitoring unit is developed as a recording speedometer, the signal detected by the pulse generator is evaluated for monitoring uniting compliance with the social-welfare regulations length of driving and periods of rest for drivers and/or compliance with traffic regulations concerning with respect to the maximum speed permissible for the vehicle. For this purpose, the signal detected by the pulse generator is, as is known, frequently subjected to various manipulations in order generally to exert an illegal influence on the path of the transmission of the signal from the pulse generator to the monitoring unit. The countermeasures which have been applied up to now, which are directed at simultaneously transmitting an inverted signal with respect to the detected signal over another parallel line provided in addition to the signal line and then evaluate the two signals comparatively in the monitoring unit, have proven insufficient, since devices have become known which, when introduced into the transmission path from pulse generator to monitoring unit are able to simulate this double pulse of said monitoring unit without the illegal manipulating being detectable by recording in the monitoring unit.
SUMMARY OF THE INVENTION
It is an object of the present invention to improve the reliability of a data transmission device present in a vehicle which comprises of a pulse generator and a monitoring unit with regard to the signal to be transmitted and to provide a development of the pulse generator which is suitable for that purpose.
The data transmission device and pulse generator of the invention have the advantage of being compatible with the previously customary four-wire technique for the transmission path from the pulse generator to the monitoring unit since, as previously, two lines are required for the supplying of current and only two additional lines are required for the signal transmission. Due to the fact that the signal line which was once used for the transmission of the inverted signal is now used as data line--preferably for a bi-directional data transmission--no expensive multi-wire cables are necessary. Therefore, the data transmission device of the invention can be relatively easily retrofitted by replacement of the pulse generator and of the monitoring unit in an existing vehicle without incurring charges for the expensive laying of a new line.
Another advantage is that due to the fact that the signal detected by the sensor element of the pulse generator can also be transmitted further directly after its detection, i.e. in the form of a real-time signal, the traditional nature of the preparation of the signal in the pulse generator and in the monitoring unit can be retained. Thus circuit techniques which have proven satisfactory can continue to be used, wh
REFERENCES:
patent: 5731785 (1998-03-01), Lemelson et al.
* no. --, Oct. 10, 1990, Jackson J S. pp. 29-32, XP000222750 Cooke L: Sensor Technology and Signal Analysis: High Security Encryption Supervision.
* Proceedings of the International Carnahan Conference on Security Technology: Crime Countermeasures, Lexington, Oct. 10-12, 1990.
Bacic Helmut
Buscher Ludwig
Grill Thomas
Gruler Martin
Lais Norbert
Farber Martin A.
Mannesmann VDO AG
Shah Kamini
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