Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
  • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
  • G01S5/0252—Radio frequency fingerprinting

Definitions

• the invention relates to a system for determining the position of an object, a person or the like, comprising at least a transmitter for transmitting electromagnetic waves and at least a receiver for receiving electromagnetic waves, connected to which receiver is a positioning organ for, subject to the electromagnetic waves received by the receiver, determining a position of the object or the person located between the transmitter and the receiver, while the object or the person is not carrying the transmitter and the receiver.
• the object or the person does not form a part of the system, as the transmitter and the receiver are not physically in contact with the person or the object.
• Such a system is known from the American patent application 2006/0007001.
• the system disclosed in the American patent application 2006/0007001 uses polarized electromagnetic waves at radio frequency level, which waves, after reflection by the object to be detected, are received by several receivers . This detection and reflection of electromagnetic waves forms the basis for the detection of the object, or the determination of the position of this object.
• the system according to the invention is therefore characterized in that the at least one transmitter and the at least one receiver form a first transmitter-receiver combination having a direct radio connection, and in that the positioning organ determines the position of the object or the person on the basis of, compared with a predetermined reference level, an attenuation of electromagnetic waves as re- ceived by the receiver of the first transmitter-receiver combination .
• the system known from the American patent application 2006/0007001 is based on the reflection of electromagnetic waves transmitted by the transmitter, measures have to be taken to polarize these waves in order to be able to determine a position with sufficient accuracy.
• the transmitter and receiver have to be placed in such a way that they possess a common plane of polarisa- tion.
• the system according to the invention can be embodied more simply, which is partly due to the fact that the wave signal does not need to be polarized.
• Another important aspect of the system according to the invention is that it makes it possible to determine the position of the object by influencing the electromagnetic waves within the so-called Fresnel-zone, which zone has a width and length ratio that depends on the frequency of the waves.
• This aspect can be advantageously used to determine the size of the area of influence.
• the transmitter during use is further desirable- for the transmitter during use to be adjusted to a transmission frequency that is selected subject to the distance between the transmitter and the receiver, thereby setting a predetermined width for the Fresnel-zone . It has been shown in the context of the invention that the transmitter and the receiver are suitably effective at a frequency ranging from 850 MHz to 2.5 GHz.
• a further aspect of the invention relates to the embodiment of the system in which, during the determination of a position, the transmitter and the receiver are both designed to function at minimally two frequencies that are different from each other. This affords the possibility to recognize and eliminate measuring errors caused by multipath, because multipath produces different results for different frequencies .
• the system according to the invention can be used for various purposes, but is especially suitable for determining whether there are any objects or persons present in predetermined spacial areas. By combining several transmitter and receiver combinations it is possible to monitor an area of practically any shape. The position of objects or persons can be determined by monitoring several adjacent areas. The reliability may be enhanced by a redundant embodiment. An example is the application in combination with a transport system for persons or goods. The system according to the invention can then be used for safety purposes, for example, for guarding a level crossing.
• FIG. 1 an embodiment of the system shown in Fig. 1, to which redundant transmitter-receiver combinations have been added.
• a rectangular area 1 is shown, provided with transmitter-receivers A, B, C, D, E and F along its boundaries.
• transmitter-receiver combinations are formed by the pairs A-B, B-C, C-F, F-E, E-D and D-A.
• Each of these transmitter-receiver combinations sustains a direct radio connection, which is characterized by the Fresnel-zones 2-7 of the just mentioned transmitter-receiver combinations.
• these transmitter-receiver combinations A-B, B-C, C-F, F-E, E-D and D-A can form a self-organizing network, wherein the attenua- tion data measured with each of these transmitter-receiver combinations concerning the radio contacts formed by these combinations, can be transmitted to a transmitter-receiver A that is linked to a position determining organ 8.
• Fig. 1 represented configuration of the sys- tern not only allows the position of an object or person within one of the Fresnel-zones 2-7 to be determined, but the system in its entirety embodies a monitoring system for the area 1.
• Fig. 2 shows a system of cooperating transmitter- receiver combinations similar to the system shown in Fig. 1.
• the system of Fig. 2 is characterized by the fact that each transmitter and/or receiver of a transmitter- receiver combination may also be part of another transmitter- receiver combination.
• several intersecting Fresnel-zones can be distinguished, for example, the Fresnel-zone 9 belonging to the transmitter—receiver combination A-F; the Fresnel-zone 10 belonging to the transmitter-receiver combination D-E and the Fresnel-zone 11 belonging to the transmitter-receiver combination D-C.
• a person or object being present in the area 1 and thus influencing the electromagnetic waves between said transmitter-receiver combinations B-E, C-D and A-F, allows this system to determine a position of a person or object with greater accuracy, because it is possible to use the attenuation data from these three different radio contacts .
• Fig. 3 shows a variant of the system shown in Fig. 1.
• the difference lies in the fact that near the transmitter- receivers A, C, F and D redundant transmitter-receivers A 1 , C, F' and D' are placed.
• the redundancy in the system thus produced with additional Fresnel-zones 4 ' , 7 ' , 12 and 13 provides the system with increased operational reliability.
• detection can simply be taken over by Fresnel-zone 7 ' belonging to the transmitter-receiver combination A '-D 1 .
• the second Fresnel-zone (with a phase shift in the range from 90°-270°) pertaining to the 2.4 GHz and the first Fresnel-zone (with a phase shift in the range from 0°-90°) pertaining to 868 MHz are practically equally large, so that in the event of the received signal being extinguished in, for example, the 2.4 GHz band, the signal of the 868 MHz band will not be extinguished such that it is still possible to obtain a useful measuring signal.
• the position determining organ 8 is preferably equipped with a so-called alpha filter with which it is possible to calculate a stabilized value of the measured attenuation value of the received radio signals .
• a filter may be adaptive through having the degree to which new attenuation values are taken into account depend on the extent to which the measured values vary. It is thus possible to filter out any variations in the measured attenuation that are of an infrequent nature and that are associated with a change in the measuring condi- tions, such as effects from the weather.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• General Physics & Mathematics (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Radar Systems Or Details Thereof (AREA)
• Position Fixing By Use Of Radio Waves (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=39199983

Family Applications (1)

Country Status (2)

Citations (3)

• 2007
  • 2007-09-07 NL NL2000845A patent/NL2000845C2/nl not_active IP Right Cessation
• 2008
  • 2008-09-05 WO PCT/NL2008/050589 patent/WO2009031898A1/en active Application Filing

Patent Citations (3)

Non-Patent Citations (1)

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