EP0685828B1 - Data transmission from a fixed station to a moving object - Google Patents

Abstract

Directions to the mobiles (28, 31, 32) to follow selected routes (eg. 29) to their allotted parking spaces (30) are encoded in the data words from fixed transmitters (35-40). Each data words contains two directional bits characterising the course of the mobile addressed, a change-of-direction bit and at least one check digit. The change-of-direction bit serves to adapt the directional bits after changes of course. The infrared transmitters and receivers operate in accordance with pulse pause modulation, yielding advantages esp. for battery-powered transmitters backed up by solar cells. <IMAGE>

Description

The invention relates to a data transmission device for transmitting a data word from a fixed station to a moving body with at least one data transmission unit located along the movement path for transmitting a transmission signal and a data receiver unit located on a moving body for receiving the transmission signals and with at least one storage unit contained in the data receiver unit for Storage of the data, at least one data evaluation unit contained in the data receiver unit for evaluating the data and at least one display unit contained in the data receiver unit for displaying the data. The invention further relates to a corresponding method for transmitting data and the use of the data transmission device and the method for the automatic detection of signals.

Data transmission systems are known in different designs and are widely used where part of the transmission system is freely movable and the distance to be bridged is limited to a few meters. Infrared (IR) transmission systems have proven their worth, particularly in the area of automatic route control of transport devices. Such transmission systems are particularly advantageous if several independent systems are used in parallel in the environment. Other transmission media, such as the high-frequency signals up to frequencies of a few hundred MHz, can practically not be used for such transmission links, since - when using several transmitters with the same frequency - decoupling of the signals is practically impossible. But even at different frequencies, the use of high-frequency signals is not always possible if electromagnetic interference fields are present in the local environment (WO 86/02637).

With regard to the type of transmission, pulse code modulation is often used in IR transmission systems.

In addition to the data to be transmitted, a not inconsiderable number of system-specific synchronization characters, such as start bit, reset bit, must also be transmitted. For example, for the relatively small amount of data of 4 bits, an additional 6 bits are required to control the 4-bit data word (DE-A-31 46 251).

If larger amounts of data are to be transmitted, relatively long transmission times have to be accepted. By dividing the data into several blocks and parallel instead of serial transmission, the transmission time can be shortened, but requires more circuitry, since several data transmitters and several data receiver units are required for parallel operation (DE-C-36 15 825).

One area of application for such data transmission devices is the automatic detection of signals for road traffic and for the reproduction of these signals in motor vehicles. The purpose of such devices is to enable the driver of a motor vehicle to call up the traffic signs in his motor vehicle that are valid in the section of road he is traveling on (DE-U-94 09 056).

A device for receiving and transmitting information between fixed and movable stations for determining and transmitting climate and road information is known, the at least one data transmission unit located along the movement path for transmitting a transmission signal and a data receiver unit located on a moving body for receiving the transmission signal and with at least one memory unit contained in the data receiver unit for storing the data and a data evaluation unit for evaluating the data (EP-A-0 575 907).

In order to transmit the data word to be transmitted from one base station to a data receiver unit located on a moving body with only one data transmission unit, to shorten the transmission time by saving control characters, and to additionally transmit its validity with respect to the direction of movement of the body coded into the data word a new transmission method can be invented that avoids the disadvantages of known systems.

Starting from the prior art, the invention has for its object to provide a data transmission device by means of infrared light, with which a relatively small amount of data can be transmitted from a fixed station to a moving body, a distinction being made between two directions of movement of the body, which in the data word refer to their Validity as direction bits are recognizable. This object is achieved in that the transmitted data word contains at least one direction bit characterizing the direction of movement of the body and at least one direction change bit that takes into account changes in the direction of movement and at least one evaluation bit, and that the data transmitter and receiver units also have pulse-pause modulation working infrared transmitting and receiving devices are equipped.

The decisive advantage of the data transmission device according to the invention is that instead of the pulse code modulation usually used, the pulse-pause modulation is used, and that at the same time a direction coding is contained in the data word to be transmitted.

Another decisive advantage of the data transmission device according to the invention is that the pulse-pause modulation of the transmitting part and the Power supply part of the data transmission unit can be considerably relieved, since the pulse breaks are synonymous with less current and thus less power. This advantage is particularly important if, for example, the data transmission unit is powered independently of the mains from a battery or an accumulator outdoors. If, for example, a rechargeable battery is used as the power source for the data transmitter, which in turn is buffered via solar cells, the use of pulse-pause modulation also reduces the effort in terms of the required number of solar cells.

It is a particular advantage of the data transmission device according to the invention that the data transmission device takes into account changes in the direction of movement of the body, as a result of which only data words are processed in the data receiver unit which are valid according to the direction of movement of the body and its associated direction coding.

An embodiment of the invention consists in that the transmitted data word contains two direction bits characterizing the direction of movement of the body and a direction change bit as well as at least one evaluation bit.

According to the invention it is provided that the data word to be transmitted can be transmitted cyclically by the data transmission unit as a continuous signal.

It is advantageous that when a data word is received in data receiver units in which no direction bit has yet been stored, the direction bit contained in the data word can be adopted and can be stored in the data receiver unit as a direction bit if the direction change bit is not set in the data word.

It is within the scope of the invention that when a data word is received in which both the direction bit and the direction change bit are set, in data receiver units in which no direction bit has yet been stored, the direction bit not set in the data word can be invertedly accepted and stored in the data receiver unit.

It is also expedient that when a data word is received in data receiver units in which a direction bit has already been set, the evaluation bits can be transferred to a buffer in the memory unit and evaluated by the evaluation unit if the direction bit contained in the data word and the direction bit stored in the data receiver unit are the same, and the evaluation bits contained in the data word differ in at least one bit from the data stored in the buffer, regardless of whether the direction change bit is set in the data word.

A further development of the invention consists in the fact that the transfer of the evaluation bits into the buffer can be triggered by a transfer pulse.

According to the invention, when a data word is received in which the direction change bit, but no direction bit is set, in data receiver units in which a direction bit is stored, the stored direction bit and all displays of the evaluation bits can be deleted.

It is advantageous that when a data word is received in which the direction change bit, but no direction bit is set, in data receiver units in which no direction bit is stored, the data word cannot be adopted.

• das zu übertragende Datenwort besteht aus mindestens einem, die Bewegungsrichtung des Körpers kennzeichnenden Richtungsbit, einem Änderungen der Bewegungsrichtung berücksichtigenden Richtungsänderungsbit sowie mindestens einem Auswertebit und wird zyklisch ausgesandt,
• beim Empfang eines Datenwortes in Datenempfängereinheiten, in denen noch kein Richtungsbit gespeichert ist, wird das im Datenwort enthaltene Richtungsbit übernommen und im Datenempfänger als Richtungsbit gespeichert, wenn im Datenwort das Richtungsänderungsbit nicht gesetzt ist,
• beim Empfang eines Datenwortes, in dem sowohl Richtungsbit als auch Richtungsänderungsbit gesetzt sind, in Datenempfängereinheiten, in denen noch kein Richtungsbit gespeichert ist, wird das im Datenwort nicht gesetzte Richtungsbit invertiert übernommen und gespeichert,
• beim Empfang eines Datenwortes in Datenempfängereinheiten, in denen bereits ein Richtungsbit gesetzt ist, werden nur dann die Auswertebits in einen Zwischenspeicher übernommen und von der Auswerteeinheit ausgewertet, wenn das im Datenwort enthaltene Richtungsbit und das in der Datenempfängereinheit gespeicherte Richtungsänderungsbit gleich sind, und sich die im Datenwort enthaltenen Auswertebits in mindestens einem Bit von den im Zwischenspeicher gespeicherten Daten unterscheiden, unabhängig davon, ob im Datenwort das Richtungsänderungsbit gesetzt ist,
• beim Empfang eines Datenwortes, bei dem das Richtungsänderungsbit, jedoch kein Richtungsbit gesetzt ist, werden in Datenempfängereinheiten, in denen ein Richtungsbit gespeichert ist, das gespeicherte Richtungsbit und alle Anzeigen der Auswertebits gelöscht,
• beim Empfang eines Datenwortes, bei dem das Richtungsänderungsbit, jedoch kein Richtungsbit gesetzt ist, wird in Datenempfängereinheiten, in denen kein Richtungsbit gespeichert ist, das Datenwort nicht übernommen und nicht ausgewertet.

The method according to the invention for transmitting a data word from a fixed station to a moving body, wherein at least one data transmission unit for transmitting a transmission signal and a data receiver unit located on the moving body for receiving the transmission signals as well as at least one storage unit in the data receiver unit for storing the data along the movement path, at least one data evaluation unit and at least one display unit for displaying the data are characterized by the following method steps:

• the data word to be transmitted consists of at least one direction bit which characterizes the direction of movement of the body, a direction change bit which takes account of changes in the direction of movement and at least one evaluation bit and is transmitted cyclically,
• when a data word is received in data receiver units in which no direction bit is yet stored, the direction bit contained in the data word is adopted and stored in the data receiver as a direction bit if the direction change bit is not set in the data word,
• upon receipt of a data word in which both the direction bit and the direction change bit are set in data receiver units in which no direction bit has yet been stored, the direction bit not set in the data word is accepted and stored inverted,
• When a data word is received in data receiver units in which a direction bit is already set, the evaluation bits are only transferred to a buffer and evaluated by the evaluation unit if the direction bit contained in the data word and the direction change bit stored in the data receiver unit are the same, and the im Distinguish the evaluation bits contained in the data word in at least one bit from the data stored in the buffer, regardless of whether the direction change bit is set in the data word,
• upon receipt of a data word in which the direction change bit, but no direction bit is set, the stored direction bit and all displays of the evaluation bits are deleted in data receiver units in which a direction bit is stored,
• when a data word is received in which the direction change bit is set, but no direction bit is set, the data word is not accepted and not evaluated in data receiver units in which no direction bit is stored.

A further development of the method consists in the fact that the takeover of the evaluation bits into the buffer is triggered by a takeover pulse.

The use of the data transmission device or of the method for transmitting data in a device for automatically detecting signals for road traffic and for reproducing these signals in motor vehicles is also in accordance with the invention.

The use of the data transmission device or the method for transmitting data in a device for automatically recording taxi information at airports and for reproducing the taxi information in aircraft is also in accordance with the invention.

Details and advantages of an exemplary data transmission device according to the invention are explained in more detail below with reference to drawings.

Fig. 1

schematisch die in Puls-Pausen-Modulation arbeitende Datensendeeinheit am Beispiel eines 10-Bit-Datenwortes;

Fig. 2

schematisch die in Puls-Pausen-Modulation arbeitende Datenempfängereinheit;

Fig. 3

schematisch die Schaltung, der in der Datenempfängereinheit enthaltenen Richtungsdecodierung;

Fig. 4

die Wahrheitstabelle zu der in der Richtungsdecodierung enthaltenen Richtungslogik;

Fig. 5

die Schaltung zur Übernahme der im Datenwort enthaltenen Auswertebits;

Fig. 6

die Schaltung zur Decodierung der Auswertebits mit dem Anzeigeteil;

Fig. 7

ein Beispiel zur Realisierung, der in der Wahrheitstabelle (Fig. 4) enthaltenen Ausgangsgröße T1' mit digitalen Schaltgliedern;

Fig. 8

Beispiel zur Realisierung der in der Wahrheitstabelle (Fig. 4) enthaltenen Ausgangsgröße T2' mit digitalen Schaltgliedern;

Fig. 9

Beispiel zur Realisierung der in der Wahrheitstabelle (Fig. 4) enthaltenen Ausgangsgrößen RS' und Ü mit digitalen Schaltgliedern;

Fig. 10

zwei Zeichnungen zu den beiden Anwendungsbeispielen der erfindungsgemäßen Datenübertragungseinrichtung.

Show it:

Fig. 1

schematically the data transmission unit working in pulse-pause modulation using the example of a 10-bit data word;

Fig. 2

schematically the data receiver unit working in pulse-pause modulation;

Fig. 3

schematically the circuit of the directional decoding contained in the data receiver unit;

Fig. 4

the truth table for the directional logic contained in the directional decoding;

Fig. 5

the circuit for taking over the evaluation bits contained in the data word;

Fig. 6

the circuit for decoding the evaluation bits with the display part;

Fig. 7

an example of the realization of the output variable T1 'contained in the truth table (FIG. 4) with digital switching elements;

Fig. 8

Example for realizing the output variable T2 'contained in the truth table (FIG. 4) with digital switching elements;

Fig. 9

Example for realizing the output variables RS 'and Ü contained in the truth table (FIG. 4) with digital switching elements;

Fig. 10

two drawings of the two application examples of the data transmission device according to the invention.

1 shows the data transmission unit with an integrated circuit 1, which converts a data word present in parallel at the inputs 2, which are designated D1 to D10, into a serial data stream. In this case, the data word is converted into a sequence of individual pulses, with the state logic "0" being assigned a short pause between two individual pulses and the state logic "1" being assigned a long pause between two individual pulses. The break ratio here is 1: 1.8. The output 3 of the integrated circuit controls the infrared transmitter diode 5 via the amplifier stage 4, which in turn emits the serial data stream as a single pulse sequence. The internal clock frequency of the IC is determined with the RC element 6. A favorable value for this is, for example, 500 kHz. The duration of a single pulse is equal to the period of the clock frequency (here: 2µs). The duration of the pulse pause for logic "0" is 10 clock periods (here: 20µs), and the duration of the pulse pause for logic "1" is 18 clock periods (here: 36µs). Bit pattern 7 shows an example of a 10-bit data word consisting of 11 pulses. If the continuous signal operating mode is selected for the integrated circuit 1, the transmission of the data word is repeated cyclically, with a pause between the transmissions of the data words of 8192 clock pulses. The time intervals between the data word transmissions are therefore approx. 17 ms.

D1

Richtungsbit für Bewegungsrichtung A des Körpers

D2

Richtungsbit für Bewegungsrichtung B des Körpers

D3

Richtungsänderungsbit

D4 bis D10

Auswertebits.

The 10 bits of the data word are defined as follows:

D1

Direction bit for direction of movement A of the body

D2

Direction bit for direction of movement B of the body

D3

Direction change bit

D4 to D10

Evaluation bits.

2 shows the data receiver unit with an integrated circuit 8, which receives the serial data word via the infrared sensor 9 and supplies it to the IC 8. The internal clock frequency of the IC 8 is set with the RC element 10. It corresponds to the same frequency as that of the data transmitter IC 1. If the data receiver unit has received a complete data word, the 10 bits of the data word are converted back by the IC 8 from a serial data word into a parallel data word and sent to the outputs D1 to D10 11 created. A strobe pulse 12 enables the data word to be accepted.

3 shows the directional decoding of the data receiver unit according to the invention. It consists of the direction logic 13, the two flip-flops 14A, 14B for storing the direction bits, 3 AND elements 15 for linking the logic output variables RS ', T2' and T1 'with the strobe pulse and an OR element 16 to darken the display part, which will be explained later.

D3

Richtungsänderungsbit vom Ausgang der Datenempfängereinheit 8

D1

Richtungsbit für Bewegungsrichtung A des Körpers

D2

Richtungsbit für Bewegungsrichtung B des Körpers

ST

Strobe-Impuls vom Ausgang der Datenempfängereinheit 8 zur Datenfreigabe

T1

Takt für Flip-Flop 14A der Bewegungsrichtung A

T2

Takt für Flip-Flop 14B der Bewegungsrichtung B

RS

Reset zum Rücksetzen der beiden Flip-Flops 14A, 14B

QA

gespeichertes Richtungsbit für Bewegungsrichtung A

QB

gespeichertes Richtungsbit für Bewegungsrichtung B

Ü

Übernahme-Impuls 18 zur Übernahme der Auswertebits D 4 bis D 10 17 in den Zwischenspeicher 19

F

Freigabesignal 20 zur Anzeige der Auswertebits bzw. zur Dunkelsteuerung der Anzeigen 21 und 25.

In particular, they mean:

D3

Direction change bit from the output of the data receiver unit 8

D1

Direction bit for direction of movement A of the body

D2

Direction bit for direction of movement B of the body

ST

Strobe pulse from the output of the data receiver unit 8 for data release

T1

Clock for flip-flop 14A in the direction of movement A

T2

Clock for flip-flop 14B of direction B

RS

Reset to reset the two flip-flops 14A, 14B

QA

stored direction bit for direction of movement A

QB

stored direction bit for direction of movement B

Ü

Take-over pulse 18 for taking over the evaluation bits D 4 to D 10 17 in the buffer memory 19

F

Release signal 20 for displaying the evaluation bits or for darkening the displays 21 and 25.

The relationship between the input variables D1, D2, D3, QA and QB with the output variables T2 ', T1', RS 'and Ü is summarized in the truth table (FIG. 4).

The left column of the table numbers the possible combinations of the input variables from 1 to 32. The following explanations are limited to the input combinations that can occur in the area of the data transmission system according to the invention. The input combinations that cannot occur can be recognized by the fact that the associated output variables are marked with a cross as "don't care terms".

The input combinations of the directional logic that can occur during operation are explained below. This is followed by an exemplary embodiment for implementing the equations found from the truth table with the aid of discrete digital switching elements.

The input states of numbers 5 and 9 mean that the data receiver unit has not yet received a data word from the time it was started up. If the data receiver unit now receives a data word in which the direction bit D1 is set, the direction bit D1 is loaded into the directional flip-flop 14A with the clock T1 or, at No. 9, the direction bit D2 with the clock T2 is loaded into the directional Flip-flop 14B. In both cases, the evaluation bits D4 to D10 17 are loaded with the takeover pulse Ü 18 from the data receiver unit IC 8 into the buffer memory 19 and released with the enable signal F 20 to the displays 21 and 25.

The input states of numbers 6 and 11 mean that a direction bit is already stored in the data receiver unit and the same direction bit is contained in the received data word, as a result of which the takeover pulse Ü 18 allows the evaluation bits D4 to D10 17 to be taken over. This occurs when the data receiver unit receives a data word that is valid for it.

The input states with the numbers 7, 10, 23 and 26 mean that the stored direction bit and the direction bit transmitted in the data word are not identical, as a result of which the received data word is not accepted and is not evaluated. In these cases, the data word is intended for receivers in which the direction of movement of their bodies does not match the direction of movement of the body that has stored this direction bit.

The input states with the numbers 21 and 25 mean that both the direction change bit D3 and a direction bit are set in the data word. However, since the data receiver unit had not yet received a data word since it was started up, which can be seen from the unset directional flip-flops 14A, 14B, the evaluation bits 17 are accepted in the data receiver unit with the takeover pulse 18 and the direction bit which has not been transmitted is then inverted and stored in the corresponding flip-flop. This occurs when the direction bit is to be changed without a direction bit being stored in the data receiver unit.

The input states with the numbers 22 and 27 mean that both direction change bit D3 and a direction bit are set in the data word. Since the stored direction bit and the direction bit are identical in the data word, the evaluation bits 17 can be adopted. Thereafter, a pulse is sent to both directional flip-flops 14A, 14B via T1 and T2, whereby their outputs are reversed and the change in the stored direction bit is completed. This occurs when the stored direction bit is to be changed due to the change in the direction of movement of the body.

$$\text{T1' = (D3*((D1*QA)+(D2*QA)))+((D3*D2)*(QB*QA))}$$

$$\text{RS' = ((D2*D1)*D3)*(QA+QB)}$$

$$\text{Ü = (D2*QA)+(D1*QB)}$$

mit

• * Und-Verknüpfung
• + Oder-Verknüpfung
• ― Negation

The input states with the numbers 17, 18 and 19 mean that regardless of whether a direction bit is stored in the data receiver unit, all displays are to be darkened and in the cases of the numbers 18 and 19 both flip-flops 14A, 14B are deleted via RS will. This occurs when the moving body has reached its target point at which the stored and displayed data lose their validity.
The transfer of the truth table (Fig. 4) into KV diagrams provides the following equations, taking switchgear simplifications into account: $$\text{T2 '= (D3 * ((D1 * QB) + (D2 * QB))) + ((D3 * D2) * (QB * QA))}$$

$$\text{T1 '= (D3 * ((D1 * QA) + (D2 * QA))) + ((D3 * D2) * (QB * QA))}$$

$$\text{RS '= ((D2 * D1) * D3) * (QA + QB)}$$

$$\text{Ü = (D2 * QA) + (D1 * QB)}$$

With

• * AND link
• + OR link
• - negation

The implementation above Equations with discrete digital switching elements are shown in FIGS. 7 to 9. Due to the freely programmable logic modules (Generic Array Logic, GALS) available today, the equations for T2 ', T1', RS 'and Ü can be constructed with a module of this series . D flip-flops 14A, 14B are used to store the direction bits.

FIG. 5 shows the circuit for transferring the evaluation bits D4 to D10 17 from the receiver IC 8 into the buffer memory 19. Each evaluation bit is compared with an equivalence element 22 to ensure that it is identical to the bit stored in the buffer memory 19 and applied to the outputs 23. The outputs of the 7 equivalence elements are combined via a Nand element 24. The AND gate 25 combines the output signal of the Nand gate with the takeover pulse Ü 18 and the strobe pulse 12 of the data receiver unit IC 8. Are one or more evaluation bits 17 different from the stored data Q4 to Q10 and are at the same time a strobe Pulse 12 and a takeover pulse 18 at the input of the AND gate, a clock pulse is sent to all the clock inputs of the latch flip-flops 19, as a result of which the evaluation bits 17 are taken over and made available for evaluation at the outputs Q4 to Q10 . In all other cases, the evaluation bits are not transferred to the buffer.

6 shows the circuit for evaluating and displaying the evaluation bits. The assignment of the evaluation bits is arbitrary. The circuit shown here corresponds to the evaluation and display part of the second application example, which will be explained later. 6 shows the evaluation logic 24 for code conversion of the data Q4 to Q7 23A from binary to BCD, so that a 3-digit decimal number from 10 to 130 can be displayed in steps of 10 with 7-segment displays 21. The data Q8 to Q10 23B are used for signaling 25. The driver stages 26 are AND elements for dark control of the display elements 21 and 25 with the enable signal F 20 and deliver the required current in the event of ad approval.
The application of the data transmission device according to the invention is explained using the following two examples:

Application example 1

• R = nächste Zubringerstraße rechts abbiegen
• L = nächste Zubringerstraße links abbiegen
• G = geradeaus.

In the upper part of FIG. 10, an airport with the runway 27, a landing plane 28, its taxiway 29 and its lane to the parking position 30 is shown schematically. The data transmission device according to the invention is used to instruct the aircraft in its parking position. Two further aircraft 31 and 32 are to be guided from their parking positions to the runway with the data transmission device according to the invention. The information to be transmitted consists of the rolling instructions:

• R = turn right at the next feeder road
• L = turn left at the next access road
• G = straight ahead.

The taxiway of the landing aircraft is direction A, the taxiways of the starting aircraft are direction B. All aircraft have a data receiver unit 8 according to the invention. In the case of the landing aircraft, the data receiver unit 8 was switched on immediately before the data transmitter 35 according to the invention was reached. The direction bit D1 is set in the data word of the transmitter 35 and the letter R is encoded in the evaluation bits D4 to D10 17. As soon as the data receiver unit receives the data word of the data transmitter 35, the direction bit A is stored in the direction flip-flop 14A of the data receiver unit 8 and at the same time the coded information R is transferred to the display part with the takeover pulse 18 and with the release signal 20 on the display Data receiver unit 8 displayed. The direction bit A is also set in the data word of the data transmission unit 36, but the evaluation bits contain the direction information L since the direction bit of the data transmission unit and the stored direction bit in the data receiver unit match and the evaluation bits contained in the data word are different from the stored data in the buffer the current evaluation bits are loaded into the buffer and the information L is displayed. At the destination point 30 there is also a data transmission unit according to the invention, the data word of which does not contain a direction bit, but contains the set direction change bit. If the data receiver unit receives this data word, the directional flip-flops 14A, 14B in the data receiver unit are deleted, as a result of which all signals are released via the enable signal F. Ads go dark. Aircraft 31 and 32 also have data transmission units according to the invention, in the data word of which direction bit D2, corresponding to direction B, is set. The data words of the transmitters 37 and 38 contain both the direction bit D2 and the coded information R as the direction of movement, which are adopted and displayed by the data receiver units of both aircraft 31 and 32. The direction bit D2 is also set in the data word of the transmitter 39, but the evaluations bis coded contain the information L, which is taken over by the data receiver units of the aircraft 31 and 32. At the destination point 40, the direction flip-flops of the data receiver unit are deleted and the displays are darkened, since there is no direction bit in the data word 40, but the direction change bit is set. The advantage of the data transmission device according to the invention can be seen particularly in the fact that in areas in which transmitters with different directional codes are present, the data receiver units always receive and evaluate only the data word which is valid due to its directional coding.

Example of use 2

A motorway exit is shown schematically in the lower part of FIG. 10. It is assumed that a vehicle leaves the direction of travel 41 and changes to the lane 42. Since the lane 41 is defined as direction A, all data words which are sent by the data transmission unit, which are located along the lane 41, contain the set direction bit D1. The information that is encoded in the evaluation bits contains data relating to road traffic, e.g. B. Speed limits from 10 km / h to 130 km / h in increments of 10 km / h. The evaluation bits Q4 to Q7 23A, binary coded, are provided for this amount of data.

The evaluation bits Q8 to Q10 23B can also be used for other information relating to road traffic, e.g. B. No overtaking. The logic 24 shown in FIG. 6 serves to perform the code conversion binary to the BCD. If a vehicle now leaves the freeway 41 by turning right onto the freeway 42, whose direction of travel B is by definition assigned to direction bit D2, the direction bit stored in the data receiver unit must also be changed from A to B. This change can be carried out with the data transmission device according to the invention by additionally setting the direction change bit D3 in the data word of the data transmission unit 43, in addition to the direction bit D1 valid for the direction of travel 41. Thereupon both directional flip-flops 14A, 14B receive a clock pulse via T1 and T2 in the data receiver unit, whereby both flip-flops change their state. In this way, the change in the directional flip-flops 14A, 14B is completed.

Claims (13)

1. A data-transmission device for transmitting a data word from a fixed station to a moving body, with at least one data-transmitting unit (5) situated along the path of movement for emitting a transmission signal and a data-receiver unit situated on a moving body for receiving the transmission signals, as well as with at least one storage unit contained in the data-receiver unit for storing the data, at least one data-evaluation unit contained in the data-receiver unit for evaluating the data and at least one display unit contained in the data-receiver unit for displaying the data, characterized in that the transmitted data word contains at least one direction bit (D1, D2) designating the direction of movement of the body and at least one direction-change bit (D3) taking into account changes in the direction of movement as well as at least one evaluation bit (D4-D10), and the data-transmission and -receiving units are provided with infrared-transmission and -receiving devices operating in pulse-pause modulation.
2. A data-transmission device according to Claim 1, characterized in that two direction bits (D1, D2) designating the direction of movement of the body and one direction-change bit (D3) as well as at least one evaluation bit (D4-D10) are contained in the transmitted data word.
3. A data-transmission device according to Claim 1 or 2, characterized in that the data word to be transmitted can be emitted cyclically as a continuous signal by the data-transmission unit (5).
4. A data-transmission device according to Claim 1, 2 or 3, characterized in that when a data word is received in data-receiver units in which a direction bit (D1, D2) has not yet been stored, the direction bit (D1, D2) contained in the data word can be transferred and stored in the data-receiver unit as a direction bit (D1, D2), if the direction-change bit (D3) has not been set in the data word.
5. A data-transmission device according to Claims 1 to 4, characterized in that when a data word, in which both a direction bit (D1, D2) and a direction-change bit (D3) have been set, is received in data-receiver units in which a direction bit (D1, D2) has not yet been stored, the direction bit (D1, D2) not set in the data word can be transferred and stored in an inverted manner in the data-receiver unit.
6. A data-transmission device according to Claims 1 to 5, characterized in that when a data word is received in data-receiver units in which a direction bit (D1, D2) is already set, the evaluation bits (D4-D10) can be transferred into an intermediate store (19) of the storage unit and can be evaluated by the evaluation unit if the direction bit (D1, D2) contained in the data word and the direction bit (D1, D2) stored in the data-receiver unit are equal, and the evaluation bits (D4-D10) contained in the data word differ in at least one bit from the data stored in the intermediate store (19), irrespectively of whether the direction-change bit (D3) is set in the data word.
7. A data-transmission device according to Claims 1 to 6, characterized in that the transfer of the evaluation bits (D4-D10) into the intermediate store (19) can be initiated by a transfer pulse (18).
8. A data-transmission device according to Claims 1 to 7, characterized in that when a data word - in which the direction-change bit (D3), but not a direction bit (D1, D2), is set - is received, the stored direction bit (D1, D2) and all the displays of the evaluation bits (D4-D10) can be deleted in data-receiver units in which a direction bit (D1, D2) is stored.
9. A data-transmission device according to Claims 1 to 8, characterized in that when a data word - in which the direction-change bit (D3), but not a direction bit (D1, D2), is set - is received the data word cannot be transferred into data-receiver units in which a direction bit (D1, D2) has not been stored.
10. A method of transmitting a data word from a fixed station to a moving body, wherein at least one data-transmitting unit for emitting a transmission signal and a data-receiver unit situated on the moving body for receiving the transmission signals are arranged along the path of movement, and at least one storage unit for storing the data, at least one data-evaluation unit and at least one display unit for displaying the data are arranged in the data-receiver unit, characterized by the following method steps:

    • the data word to be transmitted comprises at least one direction bit (D1, D2) designating the direction of movement of the body, a direction-change bit (D3) taking into account changes in thc direction of movement and at least one evaluation bit (D4-D10), and is emitted cyclically,

    • when a data word is received in data-receiver units (9) in which a direction bit (D1, D2) has not yet been stored, the direction bit (D1, D2) contained in the data word is transferred and
    is stored in the data-receiver unit as a direction bit (D1, D2), if the direction-change bit (D3) has not been set in the data word,

    • when a data word, in which both a direction bit (D1, D2) and a direction-change bit (D3) are set, is received in data-receiver units in which a direction bit (D1, D2) has not yet been stored, the direction bit (D1, D2) not set in the data word is transferred and stored in an inverted manner,

    • when a data word is received in data-receiver units in which a direction bit (D1, D2) is already set, the evaluation bits (D4-D10) are transferred into an intermediate store (19) and are evaluated by the evaluation unit only if the direction bit (D1, D2) contained in the data word and the direction-change bit (D3) contained in the data-receiver unit (9) are equal, and the evaluation bits (D4-D10) contained in the data word differ in at least one bit from the data stored in the intermediate store (19), irrespectively of whether the direction-change bit (D3) is set in the data word,

    • when a data word - in which the direction-change bit (D3), but not a direction bit (D1, D2), is set - is received, the stored direction bit (D1, D2) and all the displays of the evaluation bits (D4-D10) are deleted in data-receiver units in which a direction bit (D1, D2) is stored, and

    • when a data word - in which the direction-change bit (D3), but not a direction bit (D1, D2), is set - is received, the data word is not transferred and not evaluated in data-receiver units in which a direction bit (D1, D2) has not been stored.
11. A method according to Claim 10, characterized in that the transfer of the evaluation bits (D4-D10) into the intermediate store (19) is initiated by a transfer pulse (18).
12. Use of the data-transmission device according to Claims 1 to 9 or of the method of transmitting data according to Claim 10 or 11 in a device for automatically detecting signals for road traffic and for reproducing the said signals in motor vehicles.
13. Use of the data-transmission device according to Claims 1 to 9 or of the method of transmitting data according to Claim 10 or 11 in a device for automatically detecting runway information at airports and for reproducing the said runway information in aeroplanes.

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