WO2019192766A1

WO2019192766A1 - Device for decoupling a signal and method for decoupling a signal

Info

Publication number: WO2019192766A1
Application number: PCT/EP2019/053252
Authority: WO
Inventors: Pio Torre Flores; Hans-Peter Meyen; Bernd Lichtenberg; Andreas Westendorf; Patrick Zerrer; Bernd GOHLICKE
Original assignee: Robert Bosch Gmbh
Priority date: 2018-04-06
Filing date: 2019-02-11
Publication date: 2019-10-10
Also published as: DE102018205202A1

Abstract

The present invention relates to the tapping of a digital signal on a signal line. In particular, the digital signal can be tapped without consuming power so that no influence on the original digital signal takes place. The tapped signal is then evaluated in order to identify a characteristic property in the signal. The tapped signal is either inverted or not before being outputted as a function of a detection of said characteristic property.

Description

description

title

Device for decoupling a signal and method for decoupling a signal

signal

The present invention relates to an apparatus and a method for

Decoupling a signal. In particular, the invention relates to the coupling out of a digital signal on a signal line.

State of the art

A wired digital signal transmission takes place in numerous

technical fields application. For example, serial bus systems are known in which serial digital data can be exchanged over two twisted insulated copper wires. An example of such a digital one

Bus system is a so-called CAN bus (Controller Area Network Bus). In such a bus system, multiple transmitting and receiving devices can be connected to a signal line. The signal line can be terminated at its ends with a defined terminating resistor.

For testing or analysis purposes, it may be of interest to access the digital data transmitted on such a bus system without the

Affecting data transmission on the signal line. In particular, this is a power-free and galvanically decoupled tap the signals on the signal line desirable.

Document DE 10 2005 042 060 A1 discloses a tap device for a wireless tapping of CAN data from a CAN line. The tap is done via the electromagnetic field, which surrounds a CAN cable. Disclosure of the invention

The present invention provides a device for decoupling a signal having the features of patent claim 1, and a method for decoupling a signal having the features of patent claim 10.

Accordingly, it is provided:

A device for coupling a digital signal with a

Detection device, an analysis device and an output device. The detection device is designed to detect a signal change on a signal line. Further, the detection means is adapted to generate a binary signal using the detected signal change

provide. The analyzer is adapted to a predetermined characteristic in a time course of the of the

Identify detection device provided binary signal. The output device is configured to invert the binary signal if the predetermined characteristic has been identified in the time history of the binary signal provided by the detector. Otherwise, i. if the predetermined characteristic has not been identified, the output device outputs the binary signal not inverted.

Furthermore, it is provided:

A method for coupling a digital signal to the steps of detecting a signal change on a signal line; and providing a binary signal using the detected signal change on the signal line. The method further comprises a step of identifying a predetermined characteristic in a time history of the provided binary signal. Finally, the method includes a step of inverting the binary signal if the predetermined characteristic has been identified in the provided binary signal, and otherwise, that is, if the predetermined characteristic is in the binary signal provided binary signal has not been identified, outputting the non-inverted binary signal.

Advantages of the invention

The present invention is based on the finding that in the

Transmission of digital signals can change the signal between two states. Depending on the type of decoupling of the signal, this can occur on a signal line for exchanging the two digital states.

In particular, the "swapping" of states is dependent on attaching a sensor to pick up the digital signals on the signal line.

It is therefore an idea of the present invention to carry this knowledge and to provide an apparatus and a method for decoupling digital signals on a signal line, which automatically corrects a swapping of the two binary states.

For this purpose, the invention provides to analyze a sequence of decoupled signals and characteristic properties in the

to identify decoupled signals. Such characteristic

Properties include, for example, a known relationship between the two binary states on the signal line. If, for example, a sequence of ones and zeros is transmitted via the signal line, then

for example, from the ratio of the time intervals, in each of which a one is transmitted to the time intervals in which a zero is transmitted, be deduced from which of the two decoupled digital states each of the one and which corresponds to zero. If, for example, it is known that, on average, the sum of the time intervals in which a zero is present on the signal line is longer than the sum of the time intervals in which a one is present on the signal line, summation or integration or averaging of the decoupled one is possible Signal to be closed, which of the two decoupled states should each be assigned to a one and which each have a zero. In addition, of course, any other properties in the data to be transmitted can be identified and evaluated.

For example, a decoupled signal can also be analyzed for known regular transmitted sequences. Furthermore, for example, a known predetermined start and / or stop sequence in the

from decoupled signals to infer whether the decoupled signal should be inverted or not.

The analysis for the identification of predetermined properties in the decoupled signal and also, if appropriate, for the inversion of the binary signal can be effected for example by means of discrete components. For example, for this purpose, circuit structures by means of discrete active and / or passive components such as resistors, capacitors,

Operational amplifiers, logic gates, etc. are used. In addition, a total or at least partial signal processing by means of a digital signal processor or the like is possible.

Although the present invention is explained in the context of binary signals, the invention is not limited to this, but the evaluation according to the invention can also be used for example for ternary signals with three different signal levels or possibly also for signals with several different signal levels.

According to one embodiment, the analysis device comprises an integrator. The integrator may be configured to integrate the binary signal provided by the detector over a predetermined period of time. By integrating or averaging the provided binary signal over a predetermined period of time, for example, it can be determined which of the two binary states occurs longer or more frequently in the provided binary signal. For example, it can be deduced from this property which of the two binary states corresponds to the state which occurs more frequently in the original signal on the signal line or on average over a relatively long period of time. According to one embodiment, the predetermined period of time corresponds to a time duration for the transmission of a predetermined number of data elements on the signal line. As a data element in this case, for example, the

Transmission of a single character. In addition, as a data element, a predetermined sequence of multiple binary

States are considered. In particular, depending on the application in the transmission, for example, each known sequences of binary

States are transmitted with a fixed number of binary characters. For the analysis and identification of characteristic

Properties in the provided binary signal are preferably a plurality of such data elements, in particular a plurality of sequences of

predetermined binary sequences analyzed together. This allows the reliability for a correct identification of the characteristic

Properties are increased. In particular, for example, two, three or moreover also, for example, ten or more such data elements can be evaluated together in order to identify predetermined characteristic properties therefrom. Also, consideration of time intervals corresponding to tens, fifteen, twenty or more data items may be used for the identification of predetermined characteristic features.

According to one embodiment, the detection device comprises a

Sensor device. The sensor device can be designed to output a voltage value corresponding to the signal change on the signal line. For example, the sensor device during a

Changing the signal on the signal line from a first state to a second state output a positive voltage signal, and in a reverse change from the second state to the first state on the signal line, a negative voltage value. In this way, a corresponding voltage value is output on each change of state on the signal line corresponding to the respective edge of the digital signal.

According to one embodiment, the sensor device may comprise a capacitive sensor. For example, the detection device, in particular the sensor device of the detection device, an electrically conductive sheath include, which completely or at least partially surrounds the signal line along a predetermined length. In this way, the electrically conductive sheath with the electrical conductor in the interior of the signal line, for example, form a cylindrical capacitor. Alternatively, even with partial enclosing, a corresponding areal capacitive decoupling can take place. During a signal change on the signal line, charging or discharging of this cylindrical capacitor takes place, whereby the respective charging or discharging currents can be evaluated. In this way, a feedback-free decoupling of the signals on the signal line is possible.

According to one embodiment, the detection device comprises a

Evaluation. The evaluation device can be designed to output a first signal value after the voltage value output by the sensor device has exceeded a first threshold value. Furthermore, the evaluation device can be designed to output a second signal value after the signal output by the sensor device

Voltage value has fallen below a second threshold. In particular, the first threshold value may be greater than the second threshold value. Such an evaluation device can be realized for example by means of a so-called Schmitt trigger. As a result, a reliable signal conditioning is possible. In particular, the two digital states on the signal line can be reliably distinguished.

According to one embodiment, the device comprises a

Transmission equipment. The transmission device may be configured to provide an output signal corresponding to the inverted or non-inverted signal output by the output device.

In particular, the transmission device can output an output signal, which in voltage level and possibly further electrical

Characteristics corresponds to a signal corresponding to the original signal on the signal line. In this way, a signal corresponding to the original signal on the signal line can be provided. According to one embodiment, identifying comprises the predetermined

characteristic feature in the method for coupling out the signal a comparison of an integration of the time course of the provided binary signal over a predetermined period of time with a predetermined threshold.

According to another embodiment, identifying the predetermined characteristic comprises identifying

predetermined binary sequences.

The above embodiments and developments can, as far as appropriate, combine arbitrarily. Further refinements, further developments and implementations of the invention also include combinations of previously or below that are not explicitly mentioned with respect to FIG

Embodiments described features of the invention. In particular, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic forms of the invention.

Brief description of the drawings

Further features and advantages of the present invention will be explained below with reference to the figures. Showing:

Figure 1: a schematic representation of a block diagram of a

Apparatus for coupling out a signal according to an embodiment; and

FIG. 2 shows a schematic representation of a flowchart on which a method for decoupling a signal according to an embodiment is based.

Embodiments of the invention

Figure 1 shows a schematic representation of a block diagram as it is based on a device 1 for coupling out a signal according to one embodiment. The device 1 for decoupling the signal comprises a detection device 10, an analysis device 20 and a

Output device 30. Furthermore, the device 1 for decoupling the Signal include a transmission device 40. As shown in FIG. 1, a digital signal can be transmitted on a signal line 2. The signal line 2 may comprise, for example, one or more copper lines surrounded by an isolation medium. For example, the

Signal line 2 twisted, insulated copper wires (twisted pair) include. Such an embodiment is used for example for the transmission of digital signals on a so-called CAN bus. Here, the leads may end up with an impedance of e.g. 120 ohms to be completed. To the signal line of such a bus, two or more transceivers (not shown) may be connected which feed the digital signals to the signal line 2 or receive digital signals. In addition, however, it is also possible that at one end of such a signal line 2, a transmitter feeds digital signals into the signal line 2, and at the other end of the signal line 2, a receiver receives these signals. However, the present invention is not limited to a signal line 2 having exactly two copper lines. In addition, it is basically also possible to evaluate digital signals on a signal line 2 with only one copper line, or to evaluate digital signals from a signal line 2 with three or more copper wires.

For decoupling the signals on the signal line 2, for example, one of the insulated copper lines with an electrically conductive material, such as a metal foil 11, are sheathed. In particular, in this case, the respective line along a predetermined length with the

Metal foil 11 are sheathed. In this way, the inner conductor binds together with the casing 11 a cylindrical capacitor.

Alternatively, it is also possible to surround the conductor only partially with an electrically conductive shell and to realize in this way a capacitive coupling. In particular, the respective insulated copper pipe can be sheathed over a length of one or several centimeters. This results in a capacity of a few picofarads (pF) for the cylinder capacitor designed in this way. In the case of a signal line 2 with two copper lines, both copper lines can each be encased by an electrically conductive material 11. In principle, however, shorter sheathed areas of a few millimeters, for example, 5mm, one centimeter or the like possible. Abe smoke smells of several centimeters are possible.

In particular, the length can be adjusted according to a thickness of the dielectric insulation of the conductor.

With a voltage increase or decrease on the respective wire of the

Signal line 2 while the so-formed cylinder capacitors are charged or discharged. These charge / discharge currents can be from a

Signal processing unit 12 of the detection device 10 are detected and evaluated. For example, the signal conditioning unit 12 may include a transimpedance amplifier that converts an input current into an output voltage. In this way, the tap of the signals on the signal line 2 can be done without power. For example, a terminal of the cylindrical capacitor can be connected to a reference potential (signal ground), and the respective other terminal of the cylindrical capacitor can also be connected to this reference potential via an operational amplifier. Thus, the voltage drop across the capacitor is zero, so that also the power to the capacitor is zero. Accordingly, no power is taken from the signal line 2. As a result, the signal on the signal line 2 without power, that is, without affecting the signal line 2 done.

In this way, with each signal change on the signal line 2 from the signal conditioning unit 12, a voltage pulse can be output. This voltage pulse can then by means of an evaluation device 13,

for example, a Schmitt trigger processed further. In particular, the evaluation device 13 can output a first signal value, for example a first electrical voltage, after the previously generated one

Voltage pulse from the signal conditioning unit 12 has exceeded a first, upper threshold. Furthermore, a second signal value, in particular a low voltage value, can be output, after which the voltage pulse from the signal conditioning unit 12 has fallen below a second, lower voltage value. In this way, a digital signal sequence can be generated, which corresponds to the digital signal on the signal line 2. The threshold values can be fixed. Alternatively, it is also possible to adjust the threshold values dynamically. For example, two corresponding conductors can be analyzed together and the Output values that correspond to the two values will be compared with each other. Accordingly, in this case, for example, the

Difference of the values corresponding to the two conductors.

Depending on which of the wires of the signal line 2 is a tap of the digital signal, the thus generated digital signal is at the output of

Evaluation device 13 either with the correct polarity available or the signal is complementary to the original digital signal on the

Signal line 2. Since when attaching a tap, for example, the electrically conductive sheath 11 on the signal line 2, a clear assignment of the respective wires is not always possible, and beyond a user's application should be facilitated in the further course

Evaluation of the tapped signal and an optionally required inversion. In this way, regardless of the connection of the tap, the tapped digital signal with the correct polarity can be output in each case.

To determine whether the signal output by the evaluation device 13 has the correct polarity or whether the polarity is complementary to the polarity of the signal on the signal line 2, a further evaluation takes place in the analysis device 20. In this case, suitable characteristic properties of the digital signal can be identified. For example, the signal output by the evaluation device 13 can be supplied to an integrator stage 21. The time constant of such an integrator stage 21 should be chosen to be sufficiently large, for example, the multiple of the length of a message on the signal line 2. In particular, for example, over a length of ten or more message durations can be integrated. The integration result can then be compared with a known ratio between the low and the high levels on the signal line 2. Accordingly, it can then be decided based on this comparison, whether the signal output by the evaluation device 13 is already correct or as

complementary signal is present. Contain, for example, the over the

Signal line 2 transmitted messages each have a uniform distribution of high and low signal levels, then there is an average of 1/2 during integration. In addition, for example, is known that between the Transmission of the individual messages of the signal levels on the signal line 2 has a high (or low) signal level, it follows from the knowledge that the average formed from the integration must be higher (or lower) than 1/2. Accordingly, it can be decided from this information whether the signal output by the evaluation device 13 has to be inverted or not.

In addition, of course, further characteristic properties can also be identified and evaluated in the analysis device 20. If it is known, for example, that a known data sequence is regularly transmitted in the data transmitted via the signal line 2, this data sequence or its inverted form can also be identified in the signal output by the evaluation device 13 in order to decide whether the signal is to be inverted should or not. For example, suitable filters or the like can be implemented in the analysis device 20 for this purpose.

The analysis device 20 can then provide a corresponding output signal to the output device 30 depending on the decision as to whether the signal output by the evaluation device 13 is to be inverted or not. The output device 30 can then, depending on this signal provided, either output the signal directly from the evaluation device 13 or invert it prior to output. For example, for this purpose, the signal received by the output device 30 in two

Signal paths are split. In a signal path, the signal from the evaluation device 13 directly at the input of a switching element 32nd

provided. In a further signal path, the signal provided is inverted in an inverter 31 and the signal thus inverted is provided at a further input of the switching element 32. The switching element 32 can then in dependence on that of the analysis device 20th

provided signal either the inverted or the non-inverted signal output. In this way, a digital signal is present at the output of the output device 30, which also corresponds with respect to the signal values to the digital signal on the signal line 2. Depending on the design of the components described above, in particular the output device 30, a digital signal is thus available which corresponds to the digital signal on the signal line 2. The levels of the so

provided signal correspond to the voltage levels of the circuit technology used. For example, the signal can be output at TTL voltage level. For further processing of the signal thus output, the signal of a transmission device 40 can be provided. The transmission device 40 may, if necessary, adjust the voltage levels. In addition, of course, any other adjustments are possible. For example, the impedance on the output side can be adapted, a corresponding driver stage for outputting a required electric power of the output signal can be provided, etc. For example, when tapping a digital signal on a signal line 2 of a CAN bus, the transmission device 40 can also provide a digital signal which is CAN compliant.

Of course, even with taps on signal lines of other transmission systems, the output signals can be adjusted by the transmission device 40 accordingly, so that by the

Transmission means 40 corresponding output signals corresponding to the signals on the signal line 2. But also the output of a signal with

Signal characteristics such as voltage, power, impedance, etc., which are different from the characteristics on the signal line 2, are possible.

Figure 2 shows a schematic representation of a flow chart, as it is based on a method for coupling a digital signal on a signal line. In step S1, a signal change on the signal line 2 is detected. In step S2, a binary signal is then provided, the provision using the detected signal change on the

Signal line takes place. In step S3, at least one predetermined characteristic in a time profile of the thus provided signal

Property identified. In step S4, the inverted signal is inverted and output if the predetermined characteristic has been identified in the provided binary signal. Alternatively, in step S5, the non-inverted binary signal is output if the predetermined one characteristic property in the provided signal has not been identified.

In addition, all embodiments, as they were previously performed in connection with the device 1 for picking up a digital signal.

In summary, the present invention relates to picking up a digital signal on a signal line. In particular, the digital signal can be tapped without power so that there is no influence on the original digital signal. The tapped signal is then evaluated to identify a characteristic property in the signal. Depending on detection of this characteristic, the tapped signal is either inverted or not before output.

Claims

claims

Claims 1. A device (1) for coupling out a digital signal, comprising: detection means (10) adapted to

Detecting signal change on a signal line (2) and providing a binary signal using the detected signal change; an analysis device (20) which is adapted to a predetermined characteristic property in a time course of the

identifying output signal means (30) adapted to invert the binary signal and then output, if the predetermined characteristic property has been identified, and to output the inverted binary signal if the predetermined characteristic property has not been identified is.

The apparatus (1) of claim 1, wherein the analyzing means (20) comprises an integrator (21) adapted to integrate the provided binary signal over a predetermined period of time.

3. Device (1) according to claim 1 or 2, wherein the predetermined

Time duration of a period of time for the transmission of a predetermined number of data elements on the signal line corresponds.

4. Device (1) according to one of claims 1 to 3, wherein

Detection device (10) comprises a sensor device (12) which is adapted to output a to the signal change on the signal line (2) corresponding voltage value.

5. Device (1) according to claim 4, wherein the sensor device (12) comprises an electrically conductive sheath (11) which surrounds the signal line (2) along a predetermined length at least partially.

6. Device (1) according to claim 4 or 5, wherein the detection device (10) comprises an evaluation device (13) which is adapted to output a first signal value after the voltage output by the sensor device (12) voltage value has exceeded a first threshold , and output a second signal value after the voltage value output by the sensor device is a second one

Threshold has fallen below.

7. Device (1) according to one of claims 1 to 6, with a

Transmission device (40), which is designed to provide an output signal which corresponds to that of the output device (30).

output inverted or non-inverted signal corresponds.

8. Method for decoupling a digital signal, comprising the steps of:

Detecting (S1) a signal change on a signal line (2);

Providing (S2) a binary signal using the detected signal change on the signal line (2);

Identifying (S3) a predetermined characteristic in a time history of the provided binary signal, and

Outputting the inverted binary signal;

Inverting (S4) the binary signal if the predetermined one

characteristic property has been identified in the provided binary signal; and

Outputting (S5) the non-inverted binary signal if the

predetermined characteristic property in the provided binary signal has not been identified.

9. The method of claim 8, wherein identifying the predetermined characteristic comprises comparing an integration of the time history of the provided binary signal over a predetermined period of time with a predetermined threshold.

10. The method of claim 8 or 9, wherein identifying the

predetermined characteristic features comprises identifying a predetermined binary sequence.