transmission device

Field of the Invention

The invention relates to a method for transmitting data using a transmission device. The invention further relates to a transmission device.

Background Art

Transmitting data is an important aspect for numerous applications, especially mobile applications. Transmitting the data comprises sending and/or receiving data, for example using the transmission device, the data being sent to or received from another transmission device. The latter may be identical to the first-mentioned transmission device.

The method may be for example used for a motor vehicle, but can be put to use for numerous other cases. For the vehicle it may be important to determine information about at least one other object in its vicinity, which may be another traffic participant, especially another vehicle, or alternatively a traffic sign, a building or another stationary object. The information may comprise a position of the other object, enabling the vehicle to calculate the relative position of the object with respect to itself. The relative position may be used for operating a driver assistance system. Such a driver assistance system can use the relative position to the at least one other object to assess the risk of collision, based on which it may initiate counter measures to avoid the collision.

It is thus obvious that security related aspects of the vehicle are based on the stability of data transmission between the vehicle and the at least one other object. If the data transmission is interrupted there is no possibility for determining the relative position and as such the driver assistance system is not fully functional.

Summary of the Invention

Technical problem to be solved

It is therefore the object of the invention to provide a method for transmitting data that is advantageous in view of the state of the art and especially is more reliable.

Technical solution

This is achieved with the method for transmitting data with the features of claim 1. The method uses a transmission device having: a mirror that is rotational symmetric with respect to a longitudinal axis and has at least one reflective surface; a light emitting system with a plurality of light sources, the light sources being located around the longitudinal axis and being directed towards the reflective surface; a light receiving system with at least a photosensitive sensor that is located around the longitudinal axis and is directed towards the reflective surface; and at least one radio antenna of a radio device, the antenna being aligned towards the reflective surface. It is intended that in a first mode of operation data is transmitted using the light emitting system and in a second mode of operation data is transmitted using the radio device. This means that the data transmission device has several ways of transmitting the data, one being based on optical means and the other on the radio device.

The optical means comprise the light emitting system and the light receiving system. However, dependent on the intended purpose of the transmission device it may be advantageous to omit either the light emitting system or the light receiving system such that the data transmission device is only suited for sending data or alternatively for receiving data. The radio device comprises a radio transmitter and/or a radio receiver, the at least one radio antenna being connected to the radio transmitter and/or receiver.

By using the two modes of operation, namely the first mode of operation and the second mode of operation, a data transmission link may be established via the optical means and/or the radio device. For this it is advantageous to choose the mode of operation that has the highest stability and/or bandwidth, i.e. the highest data transmission rate.

The transmission device can be part of transmission system which may comprise at least two transmission devices. Using such a configuration allows for increasing the area of sight and thus a higher sensibility of the transmission system in comparison with a single transmission device.

Advantageous embodiments and developments of the invention are characterized in the subsidiary claims.

In one advantageous embodiment of the invention in the first mode of operation a synchronization of a radio data link is performed using a synchronisation bandwidth that is lower than the transmission bandwidth which is used in the second mode of operation for data transmission. By default it is preferred that the first mode of operation is performed. As such the data is transmitted using the light emitting system. The light emitting system may typically have a higher bandwidth at short distanced between, a dependable handover as well as a reliable identification of several signals, but is dependent on a straight line of sight.

The radio device in contrast is independent from the existence of obstacles between the transmission device and the at least one other object, i.e. between a sender and a receiver. In addition its range is usually higher than that of the light emitting system. Because of this the radio data link is established between the radio device and the at least one other object, even while an optical data link via the light emitting system is available. However, the synchronization of the radio data link is performed with the synchronization bandwidth which is much lower than the bandwidth that is available for the optical data link and/or the transmission bandwidth which is used in the second mode of operation.

In summary the method uses two data links, namely the optical data link and the radio data link. The optical data link employs the optical means, i.e. the light emitting system and/or the light receiving system of the transmission device, to establish a data connection between a sender and a receiver. The sender may be the transmission device, while the receiver corresponds to the at least one other object, which may be or comprise another transmission device. The radio data link between the sender and the receiver is established via the radio device and its antenna.

During the first mode of operation the optical data link is used to transmit the data. However, the radio data link is also established, albeit at a synchronisation bandwidth that is lower than the transmission bandwidth, i.e. the maximum bandwidth that may be available in the second mode of operation. For example the synchronisation bandwidth is at most 50 %, at most 25 %, at most 10 % or at most 5 % of the transmission bandwidth. Because of the lower bandwidth the radio device may be operated with very low energy consumption. The synchronization of the radio data link may be performed permanently or in intervals.

In a further favourable embodiment of the invention the current mode of operation is switched from the first mode of operation to the second mode of operation if a current bandwidth of transmitting data using the light emitting system is lower than a bandwidth threshold. As already explained usually the optical data link is used for transmitting the data. However, if the bandwidth of said data link decreases, for example because of increasing distance between the transmission device and the at least one other object and/or because of obstacles in the line of sight, the data link is established via the radio device. For this purpose the current mode of operation is set to the second mode of operation in which the data is transmitted using the radio device, i.e. via the radio data link.

In another favourable embodiment of the invention the current mode of operation is switched from the second mode of operation to the first mode of operation if the current bandwidth of data transmission using the light emitting system is equal to or higher than the bandwidth threshold. As long as the data link may be established via the optical means, i.e. especially the light emitting system, the first mode of operation is preferred because of the advantages that have previously been described. As such, during the second mode of operation a synchronization of the optical data link is performed constantly or in intervals. This means that as soon as the optical data link can be established or re-established with an adequate bandwidth the current mode of operation is again switched to the first mode of operation.

Further, another embodiment may be devised, wherein each light source has a wave length that is different from the wave length of the other light sources. Such a configuration allows not only for transmitting data but also has the advantage of providing a possibility of determining the direction of the transmission device and/or the at least one other object.

In a further favourable embodiment of the invention a first relative angle is determined from the angular position of a light signal on the sensor with respect to the longitudinal axis, the light signal corresponding to a light detected by the sensor, and wherein a second relative angle is determined from the wave length of the detected light. The transmission device therefore not only serves for the purpose of transmitting data but further for optical position detection. The position detection comprises for example the detection of the position of the transmission device itself and/or the position of another object, especially another transmission device. The latter may be identical to the first-mentioned transmission device. The position in general may comprise at least an angle and/or at least a distance. For example, the method offers the possibility of determining the angle between a direction of the transmission device and the direct line between the center point of the transmission device and the center point of the other object.

In summary, the method does not rely on radio waves, but is based on light and - accordingly - optical means instead. The transmission device on which the method is based has the light emitting system for emitting light as well as the light receiving system for receiving light. The light emitting system provides a plurality of light sources which differ from each other with respect to their wave length. This means that each light source has a wave length that is unique with respect to the light emitting system. The light sources are located around the longitudinal axis of the mirror or the transmission device respectively. Preferably each light source has the same radial distance to the longitudinal axis as each of the other light sources. It is also preferred that the light sources are distributed evenly around the longitudinal axis resulting in equal circumferential distance between all light sources in direct neighbourhood. The light sources are directed towards the reflective surface. This means that the light that is emitted from each light source is directed to the mirror and is reflected by it.

As the mirror is rotational symmetric with respect to the longitudinal axis the light is reflected by the mirror for each light source in an identical manner. The mirror may have a protrusion that is directed along the longitudinal axis in direction of the light emitting system and/or the light receiving system, especially the sensor of the light receiving system. This means that in longitudinal-section the mirror is defined by a curve which most favourably is perpendicular to the longitudinal axis at the center of the mirror and/or at the outer edge of the mirror. The mirror is a body of revolution, i.e. a rotational solid, with respect to the longitudinal axis.

Because of the protrusion of the mirror, the angle of reflection changes with respect to the point in which the light of each light source intersects with the mirror, i.e. its reflective surface. For example the light sources are directed in a way that the light intersects with the mirror such that it is reflected outwardly in radial direction with respect to the longitudinal axis. Most favourably the thus reflected light runs perpendicular to the longitudinal axis. To achieve this, the light sources may be directed towards an imaginary line on the reflective surface which forms a circle around the longitudinal axis. The circle is placed on the mirror in a location in which the curve defining the mirror has a slope of, for example, 20° to 65°, 30° to 55° or 35° to 50°, especially 36° to 45°, most favourably 36° or 45°, with respect to the longitudinal axis. In other words, in a longitudinal-sectional view a tangent on the curve in the point in which the circle intersects with the curve encloses an angle within said ranges or with one of said values with the longitudinal axis. Of course the angle may be differently chosen for different purposes.

The mirror and its reflective surface are most favourably configured to reflect the light of each light source in a different direction, especially in a different radial outward direction with respect to the longitudinal axis. As such, the wave length of the light is an indicator for the orientation of the transmission device.

The transmission device further comprises the light receiving system with the at least one photosensitive sensor. The sensor is located around the longitudinal axis, for example its center is positioned on the longitudinal axis. The sensor is directed towards the reflective surface, such that light that is reflected by the surface may be redirected towards the sensor. If, for example, light reaches the transmission device from the outside in radial direction and falls on the mirror, that light is redirected by the mirror to fall on the photosensitive sensor in order to be further assessed.

If several of these transmission devices are present, one of the transmission devices, which acts as a sender, emits light via its light emitting system, while another one of the transmission devices, acting as a receiver, receives the emitted light using its light receiving system. Both transmission devices have an orientation, i.e. an angular position, in regard to their respective longitudinal axis. The receiver may now calculate at least one of the first relative angle and the second relative angle, preferably both relative angles, based on information that is extracted from the light that has been emitted by the sensor and received by the receiver.

In this regard the first relative angle is determined from the angular position of the light signal on the sensor with respect to the longitudinal axis. This means that the angular position of the light signal is evaluated and the first relative angle, i.e. the angular position, is deduced from it. The light signal in this context corresponds to the light detected by the sensor and as such to light emitted by the sender. Using the sensor of the light receiving system not only the angular position but also the wave length of the detected light, i.e. the light signal, is assessed. From the wave length the second relative angle can be determined which corresponds to the orientation of the sender with respect to the sender's longitudinal axis.

As already explained, the light emitting system, in this case the sender's light emitting system, has a plurality of light sources which may be differentiated using their wave length, because each light source has a wave length that is different from the wave length of the other light sources of the sender's light emitting system. It is thus possible to deduce the orientation of the sender relative to the receiver. In a favourite embodiment of the invention, a relative position of the sender is determined using the first relative angle and a distance between the sender and the receiver and/or the first relative angle corresponds to an orientation of the receiver and/or the second relative angle corresponds to an orientation of the sender.

In one advantageous embodiment of the invention, the light signal is selected from several light signals to have the highest light intensity. If the number of light sources in the sender's light emitting system is high enough, there is the possibility that several light signals, corresponding to different light sources of the sender, are received by the photosensitive sensor of the receiver. As the distance between the sender's light sources and the photosensitive sensor of the receiver differs according to the first relative angle and/or the second relative angle, only the light signal with the highest light intensity on the receiver's sensor is used as the light signal from which the first relative angle and/or the second relative angle is determined. This means that several light signals are detected by the sensor. However, only the light signal with the highest intensity is further considered for determining the first relative angle and/or the second relative angle.

In still another embodiment of the invention a center of the light signal is used to determine the angular position of the light signal. The light signal will usually not be received by the photosensitive sensor as single light point, i.e. activating only a single cell of the sensor, from which the angular position may be instantly deduced. Instead, the light signal will cover a certain area of the sensor. This is for example due to a widening of the light beam on its way from the sender's light emitting system towards the receiver's light receiving system.

Because of this, the center of the light signal is interpolated from the signal that is provided by the sensor. For example, the sensor has a plurality of photosensitive areas or cells which are activated by the light signal. For example, the interpolation can be performed by determining a minimum angular position of the light signal and a maximum angular position. The center of the light signal or the angular position from which the first relative angle is determined can now be calculated from the minimum angular position and the maximum angular position, for example by calculating the average of both values. Another possibility is to determine the light intensity of the light signal for different angular positions which are covered by the light signal. The center of the light signal is in this case assumed to have the highest light intensity within the light signal. Both methods described above may be combined in order to improve accuracy.

The invention further relates to a transmission device, in particular for carrying out a method according to the description, the device comprising: a mirror that is rotationally symmetric with respect to the longitudinal axis and has at least one reflective surface; a light emitting system with a plurality of light sources, the light sources being directed towards the reflective surface; a light receiving system with at least a photosensitive sensor, the sensor being directed towards a reflective surface; and at least one radio antenna of a radio device, the antenna being aligned towards the reflective surface. The transmission device is configured to transmit data using the light emitting system in a first mode of operation and to transmit data using the radio device in a second mode of operation.

The advantages of such a practice and such a configuration of the transmission device have already been explained. The transmission device and the corresponding method for transmitting data may be embodied and/or improved according to the antecedent description to which is expressly referred.

In a further embodiment of the invention the mirror has a central protrusion directed towards the sensor of the light receiving system. This means that the mirror or more precisely its reflective surface has a distance in longitudinal direction with respect to the longitudinal axis to the light emitting system and/or the light receiving system that is lesser at its center than at its outer edge. As already explained, the mirror is rotationally symmetric. In this it is a body of revolution or a rotational solid, respectively.

In this regard for the transmission device a curve defining the rotational symmetric mirror is generally S-shaped. If seen in longitudinal-section, the mirror is defined by the curve starting at the center of the mirror and ending at its outer edge. The curved may have any shape; especially it may be a straight line or curved with a constant curvature. However, it is favourably if the mirror is S-shaped. This means that the curvature of the curve changes its sign between the center of the mirror and the outer edge, preferably in the middle. It may be the case the curve is point-symmetric with regard to the point in which the coverture changes its sign, for example the mid-point of the curve.

It may also be the case that the curve is perpendicular to the longitudinal axis at the center of the mirror and/or at its outer edge. This means that an imaginary tangent to the curve at the center or at the outer edge encloses an angle of 90° with the longitudinal axis.

In a further embodiment of the invention, the mirror, the light emitting system and the light receiving system are located in an at least partially transparent housing. For example, the housing has a transparent area which encompasses in longitudinal direction the mirror or its reflective surface, respectively. With such an embodiment the light may leave and enter the housing through the transparent area undisturbed. However, because other areas of the housing, especially all other areas of the housing, are non-transparent or opaque, negative influences on the light emitting system and the light receiving system may be avoided. The at least one antenna may also be located inside the housing. Alternatively, it may be positioned on the housing's outside.

In yet another embodiment of the invention, the mirror and/or the light receiving system delimit the chamber of the housing. If seen in longitudinal-section the mirror and the light receiving system conclude the chamber in longitudinal direction. If the mirror has the protrusion, said protrusion is directed inwardly into the chamber of the housing. It is especially preferably if the housing is generally cylindrical, for example cylindrical with a constant radius.

In order to obtain desired optical characteristics and/or for cooling purposes, the housing, in particular the chamber, may be at least partially filled with a fluid, especially a cooling fluid. The fluid may be used to provide desired optical characteristics, for example a desired value for light reflection and/or refraction. If the fluid is used as a cooling fluid, especially for cooling the light emitting system and/or the light receiving system, the transmission device, for example its housing, is provided with connections for delivering fluid into the housing as well as for extracting the fluid from the housing. The connections may be associated with a cooling circuit for the transmission device.

In addition or in place of the fluid a lens may be placed between the mirror and the sensor of the light receiving system. The lens can in this case be used to focus the light that is redirected by the mirror towards the sensor. However, the lens may also be used to influence the light that is emitted by the light emitting system. For example, the lens may widen light beams that are emitted from the light sources of the light emitting system.

It is especially favourable if the light sources of the light emitting system are placed on a circumference of the photosensitive sensor of the light receiving system. This means that the photosensitive sensor is for example circular in cross-section and is encircled by the light sources. The light sources are favourable distributed evenly around the sensor.

Eventually, in a favourable embodiment of the invention a plurality of radio antennas is assigned to the radio device, the antennas being distributed evenly the around the longitudinal axis. This means that the transmission device does not comprise only one radio antenna although such a configuration is of course possible. Rather, several radio antennas are present, for example at least two, at least three, at least four, at least five, at least six, at least seven, at least eight or at least 12 radio antennas. Those radio antennas are favourably distributed evenly around the longitudinal axis. If the number of radio antennas is even it is advantageous if each two of the radio antennas are positioned on diametrically opposite sides of the longitudinal axis. Each antenna is aligned towards the reflective surface, meaning that electromagnetic waves that are transmitted via the antenna are directed towards the reflective surface. In the reverse radio waves that arrive at the mirror are reflected towards at least one of the antennas.

The mirror is configured to have good reflective characteristics for light as well as for radio waves. This means that the light that is emitted by the light emitting system or received by the light receiving system is diverted by the mirror, i.e. its reflective surface, as well as the radio waves that are transmitted or received via the at least one radio antenna.

The invention still further relates to a transmission system comprising at least two transmission devices according to the description by combining two, three, four or more transmission devices in different fixed orientation to each other, a more robust data transmission and/or a more precise determination of the relative angle is possible as the angle of view is enlarged with each additional transmission device. In an advantageous embodiment, several transmission devices may be arranged around a sphere, i.e. in spherical arrangement to each other. For example, two transmission devices are placed at opposite sides of an imaginary sphere and sharing the same axis. If this is done for each main axis of a sphere, the transmission system has at least six transmission devices with a view angle that covers its complete environment.

Brief Description of the Drawings

The present teachings are best understood from the following detailed description when read with the accompanying figures. The figures do not limit the scope of the invention per se but serve to explain some of its facets. Wherever practical, like reference numbers refer to like features.

Figure 1 shows a longitudinal section of a transmission device,

Figure 2 reveals a plan view on a light emitting system and a light receiving system of the transmission device,

Figure 3 depicts two transmission devices and their relative position to each other,

Figure 4 shows a photosensitive sensor of the light receiving system for an exemplary situation, and

Figure 5 depicts a plurality of transmission devices as well as exemplary sensor images from each of the devices.

Detailed Description of Embodiments

In the following detailed description, for purposes of explanation and not limitation, representative embodiments disclosing specific details are set forth in order to provide a thorough understanding of the present teachings. The description of known devices may be omitted so as to avoid obscuring the description of the example embodiments. Nonetheless, such devices, as well as materials and methods that are within the purview of one of ordinary skill in the art may be used in accordance with the representative embodiments.

Figure 1 depicts a longitudinal section through a transmission device 1 along a longitudinal axis 2 of the device 1. The device 1 comprises a mirror 3 with a reflective surface 4, a light emitting system 5 and a light receiving system 6. The light emitting system 5 has a plurality of light sources 7, of which two are shown here exemplary. The light emitting system 5 may have any number of light sources 7, preferably at least four light sources 7. A higher number of light sources 7 is of course possible, for example the light emitting system 5 has at least six, at least eight, at least 10, at least twelve, at least sixteen, at least twenty-four, at least thirty-six, at least forty-eight or at least seventy-two light sources 7.

Each light source 7 is configured to emit light having a wave length that is different of the wave length of light that is emitted by the other light sources 7. In short, each light source 7 has a wave length that is different from the wave lengths of all of the other light sources 7. The light sources 7 are located around the longitudinal axis 2, preferably each having the same distance to said axis 2. Most favourably the light sources 7 are spread evenly around the longitudinal axis 2. At least one of the light sources 7, preferably every light source 7, may have a lens 8 in order to focus the emitted light in the direction of the mirror 3 and its reflective surface 4.

The light receiving system has at least a photosensitive sensor 9. The sensor 9 may be centred around the longitudinal axis 2. A surface 10 of the sensor 9 is most favourably perpendicular to the longitudinal axis 2. The sensor 9 is positioned to face the mirror 3 and its reflective surface 4. The mirror 3 is rotationally symmetric with regard to the longitudinal axis 2. In its center it has a protrusion that is directed towards the sensor 9. In general, the mirror 3 is a body of rotation that is defined by a curve 11 that begins at a center 12 of the mirror 3 and ends at its outer edge 13. In this exemplary embodiment the curve 11 is perpendicular to the longitudinal axis 2 at the center 12 and at its outer edge 13. However, this does not need to be the case.

In this embodiment, the light sources 7 are configured such that the emitted light intersects with the mirror 3 at a point 14 at which a tangent to the curve 11 encloses an angle a=36° with the longitudinal axis 2. However, said angle is merely exemplary; other values may be adopted. The light that is emitted by the light sources 7 and is here depicted by a line 16 reflects on the mirror 13 and its reflective surface 4 outwardly in radial direction according to a line 17. This line 17 is preferably perpendicular to the longitudinal axis 2. Points 18 in which the light of the light sources 7 intersects with the mirror 3 are exemplarily depicted as well as a mirror image 19 of the sensor 9. The mirror 3, the light emitting system 5 and the light receiving system 6 are contained within a housing 20 which is preferably cylindrical- shaped and round in cross-section. The longitudinal axis 2 is preferably a center line of the housing 20. The housing 20 is at least partially transparent, especially in an area 21 which encompasses the mirror 3 completely in circumferential direction. Outside of the area 21 the housing 20 may be opaque to avoid influences of diffused light or scattered light.

Figure 2 shows a top view on the light emitting system 5 and the light receiving system 6. Only some of the light sources 7 are exemplarily labelled. It is obvious that the light sources 7 are arranged evenly around the longitudinal axis 2 and around the sensor 9. This means that if seen in cross-section or in top view the light sources 7 are provided around an outer circumference 22 of the sensor 9 and with equal distance to the longitudinal axis 2.

Figure 3 depicts the transmission device 1 which acts as a receiver 23 as well as another transmission device 1 that acts as a sender 24. The transmission devices 1 may be identical. However, the sender 24 may alternatively be a simpler device having only the light emitting system 5. An imaginary direct line 25 connects the longitudinal axis 2 of the receiver 23 with the sender's 24 longitudinal axis 2. The orientation of the receiver 23 is indicated by line 26, the orientation of the sender 24 by line 27. The lines 26 and 27 as such indicate an angle of 0° with regard to the respective longitudinal axis 2.

Between the orientation of the receiver 23, i.e. the line 26, and the direct line 25, there is a first relative angle al, while between the sender's orientation, i.e. the line 27, and the direct line 25 there is a second relative angle α2. The distance between the axis 2 of the receiver 23 on the one hand and the axis 2 of the sender 24 on the other hand is depicted as distance d. Using the transmission devices 1 in the form of the receiver 23 and the sender 24, it is now possible to determine the first angle al and the second angle a2. Optionally, also the distance d may be determined.

The determination of the angles al and a2 is explained with reference to figure 4 which depicts an exemplary situation on the sensor 9. In this situation several light signals 28, 29, 30, 31 and 32 are received by the sensor 9. These light signals 28 to 32 originate from the sender 24 and are received by the sensor 9 of the receiver 23. From the light signals 28 to 32 the one with the highest light intensity is selected, which is the light signal 28 in this case. After this selection the angular position of the light signal 28 with respect to the longitudinal axis 2 is determined. For this, a center 33 of the light signal 28 is defined, for example by interpolation. The angular position defines the first relative angle al . This means that the orientation of the receiver 23 with respect to the direct line 25 between the receiver 23 and the sender 24 is now known. In another step, the wave length of the light signal 28 is assessed. As the light sources 7 of the sender 24 each emit light having a different wave length, the wave length of light signal 28 indicates another angle, namely the second relative angle a2.

If in addition, the transmission device 1 is configured for transmitting data via the light emitting system 5 and the light receiving system 6, a sending time information may be transmitted by the sender 24 and received by the receiver 23. The receiver 23 additionally records the receiving time, i.e. the time at which the sending time information has been received. From the difference between the sending time and the receiving time, the distance d between the sender 24 and the receiver 23 may be calculated.

Figure 5 shows an exemplary situation with a plurality of transmission devices 1, each with an exemplary situation of the sensor 9 which only serves for illustrational purposes. Every transmission device 1 serves as receiver and as sender, so as to establish a network between the plurality of the transmission devices 1. In such a configuration it is possible that the light emitted by one of the detection devices 1 is not received by every other detection device 1. In order to enable each detection device 1 to determine the relative position of all relevant detection devices 1 , each detection device 1 collects the first relative angle al, the second relative angle a2 and the distance d of as many of the other detection devices 1 as possible. It then transmits this information via its light emitting system 5 or the light sources 7 respectively.

This means that other detection devices 1 may receive this information, even if they cannot calculate it directly from a light signal received by its sensor 9. Using such a network great distances between detection devices 1 may be covered. In addition, a compensation for blocked lines of sight between some of the detection devices 1 is provided. This enables the transmission device 1 to create and/or to update a map of its surroundings. It is expressly pointed out that the detection devices 1 may be assigned to a moving object, for example a vehicle, or alternatively to a stationary object, for example a building or a traffic sign. It is also possible that in addition to the at least one detection device 1 at least one sensing device is provided which consists only of the light emitting system 5 and as such does not possess a light receiving system 6. One of the latter is preferably assigned to the stationary object which does not necessarily need information about the moving object.

Preferably the information on the other detection devices 1 is obliterated over time in order not to store unnecessary and/or outdated information. For this, each information, for example consisting of the first relative angle, the second relative angle and/or the distance, is assigned with a time stamp. On evaluating the information, the time stamp is compared to the current time and if the information is too old, it is disregarded and/or removed from memory.

The recommended amount of light sources 7 for the optical position detecting device is 24. These are distributed evenly in distances of 15° around the axis 2. With such a configuration mathematical coding, norming and/or projecting methods using basically the prime number cross constellation can minimize transformation calculations. In this way surrounding object models and descriptions for relative navigation are recommended within four-dimensional mathematical description (sphere and/or surface) to use the logical order and variance of numbers and to get less calculation work for the object recognition, tracking and future actions prediction calculating unit. In this way, the signal coding and optical hiding can be completely valid for theoretically an unlimited amount of objects.

Reverting back to figure 1 it is obvious that the transmission device 1 does not only have optical means (comprising the light emitting system 5 and light receiving system 6) but in addition also a radio device 33 with at least one antenna 34. In this example four antennas 34 are present. However, the number of antennas 34 may be adapted according to the circumstances of employment. The antennas 34 are assigned to a radio device 33, i.e. they are connected to a radio transmitter and/or a radio receiver of the radio device 33. The antennas 34 are distributed evenly around the longitudinal axis 2 and preferably each have the same distance to said axis 2. The antennas 34 are aligned towards the reflective surface 4 of the mirror 3. It is most preferable if the antennas 34 are configured such that radio waves emitted by the antennas 34 are directed towards the same point 14 at which light that is emitted by the light sources 7 intersect with the mirror 3. This is indicated by the line 35. However, it is also possible that the radio waves are directed on any point of the mirror 3, i.e. of its reflective surface 4.

As visible from figure 2 the antennas 34 are arranged around the light emitting system 5, i.e. the plurality of light sources 7. This means that the radio position of the antennas 34 with respect of the longitudinal axis 2 is larger than the radial position of the light sources 7.

The device 1 may now be operated in a current mode of operation that is selected from at least two modes of operation, namely a first mode of operation and a second mode of operation. In the first mode of operation data is transmitted using the light emitting system 5, while in the second mode of operation data is transmitted using the radio transmitter, i.e. via the antennas 34. During the first mode of operation a synchronization of a radio data link via the antennas 34 is performed using a synchronization bandwidth that is lower than a transmission bandwidth which is used in the second mode of operation for data transmission.

If in the first mode of operation the bandwidth of data transmission via the light emitting system 5 is lower than a bandwidth threshold a current mode of operation is switched to the second mode of operation. However, during the second mode of operation a synchronization process is continually or periodically performed for establishing an optical data link via the light emitting system 5 and/or the light receiving system 6. If during the synchronization process the current bandwidth of data transmission via the light emitting system 5 and/or the light receiving system 6 is equal to or higher than the bandwidth threshold the current mode of operation is switched from the second mode of operation to the first mode of operation.