Method for determining a master time signal, vehicle, and system

Abstract

A method is provided for determining a master time signal, in particular in a vehicle. The method includes the acts of: a) receiving at least one first server time signal from a first time server; b) receiving at least one second server time signal from a second time server; c) comparing the first server time signal with the second server time signal in order to determine at least one first time difference; d) storing the first time difference; e) determining an availability of the first server time signal and/or of the second server time signal; f) using the stored first time difference to determine the master time signal at least if at least one of the server time signals is not available.

Claims

1. A method for determining a master time signal in a vehicle, the method comprising the acts of: a) receiving at least one first server time signal from a first time server; b) receiving at least one second server time signal from a second time server, c) comparing the first server time signal with the second server time signal to determine at least one first time difference; d) storing the first time difference; e) determining an unavailability of the first server time signal and/or the second server time signal; f) calculating the master time signal, at least in response to determining the unavailability of the first server time signal and/or the second server time signal, using the stored first time difference; (h) transmitting the master time signal to at least one control device of the vehicle and to the first time server; and (i) operating the at least one control device and the first time server in accordance with the master time signal by adapting the master time signal as a time signal of the at least one control device and the first time server, respectively.

2. The method according to claim 1, further comprising the act of: g) storing the master time signal and/or at least one of the server time signals in a memory.

3. The method according to claim 2, wherein the master time signal and/or the at least one server time signal are stored in an encrypted form.

4. The method according to claim 1, wherein acts a) to h) are repeated periodically or upon being triggered.

5. The method according to claim 1, wherein acts a) to f) are repeated periodically or upon being triggered.

6. The method according to claim 1, further comprising the acts of: assigning weights to the first time server and the second time server; and using the assigned weights to determine the master time signal, wherein the assigned weights are stored in a memory.

7. The method according to claim 6, wherein the assigned weights are periodically or dynamically determined and stored in the memory.

8. The method according to claim 6, further comprising the act of: checking a respective weight of a respective time server when a manipulation attempt, a time leap and/or a transmission failure is determined on the respective time server.

9. The method according to claim 1, further comprising the act of: receiving the first server time signal and/or the second server time signal from a mobile terminal device, a navigation system, a vehicle clock, a radio and/or a back-end server.

10. The method according to claim 9, further comprising the act of: performing a calibration in which a server time signal is received from the back-end server and is defined as the master time signal.

11. The method according to claim 10, wherein: in performing the calibration, the master time signal is compared with the first server time signal and/or the second server time signal and weights assigned to the first time server and/or the second time server are determined as a function of a determined time difference relative to the master time signal.

12. A vehicle, comprising: a bus system configured to communicate with one or more control devices of the vehicle; a memory; a master time signal unit that determines a master time signal, the master time signal unit being configured to: receive a first server time signal from a first time server, receive a second server time signal from a second time server, compare the first server time signal with the second server time signal to determine a first time difference and to store the first time difference, determine an unavailability of the first server time signal and/or the second server time signal, calculate the master time signal, at least in response to determining the unavailability of the first server time signal and/or the second server time signal, using the stored first time difference, transmitting the master time signal to at least one control device of the vehicle and to the first time server, and operating the at least one control device and the first time server in accordance with the master time signal by adapting the master time signal as a time signal of the at least one control device and the first time server, respectively, wherein the master time signal, the first server time signal, the second server time signal and/or the first time difference is stored in the memory.

13. The vehicle according to claim 12, further comprising a memory in which a weight or weights of the first time server and/or the second time server are stored.

14. The vehicle according to claim 12, wherein the first time server or the second time server is a navigation system, a vehicle clock, a radio or a back-end server.

15. A system, comprising: one or more mobile terminal devices, a vehicle, the vehicle comprising: a bus system configured to communicate with one or more control devices of the vehicle; a memory; a master time signal unit that determines a master time signal, the master time signal unit being configured to: receive a first server time signal from a first time server, receive a second server time signal from a second time server, compare the first server time signal with the second server time signal to determine a first time difference and to store the first time difference, determine an unavailability of the first server time signal and/or the second server time signal, calculate the master time signal, at least in response to determining the unavailability of the first server time signal and/or the second server time signal, using the stored first time difference, transmit the master time signal to at least one control device of the vehicle and to the first time server, and operate the at least one control device and the first time server in accordance with the master time signal by adapting the master time signal as a time signal of the at least one control device and the first time server, respectively, wherein the master time signal, the first server time signal, the second server time signal and/or the first time difference is stored in the memory, wherein the first time server and/or the second time server are formed by a respective mobile terminal device.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIG. 1 is a schematic block diagram of an exemplary vehicle according to the invention for executing an exemplary method according to the invention for the determination of a master time signal. All transmission paths shown in dashed lines and/or the vehicle units shown in dashed lines are merely optional units and/or data connections.

DETAILED DESCRIPTION OF THE DRAWING

(2) The vehicle shown in FIG. 1 includes a first time server 10, which transmits one first server time signal SZ1 to the master time signal unit 40. Furthermore, a second time server 20 is shown, which transmits one second server time signal SZ2 to the master time signal unit 40. Preferably, the transmission of the server time signals SZ1 and SZ2 occurs by way of a secured transmission channel.

(3) The master time signal unit 40 receives the first server time signal SZ1 as well as the second server time signal SZ2, wherein in a comparer 41, a comparison occurs between the first server time signal SZ1 and the second server time signal SZ2 to determine at least one first time difference ZD.

(4) The first time difference ZD can be stored in a time difference memory 53. The time difference ZD or in this case the first time difference is transmitted into the determination unit 42, wherein furthermore the availability of the first server time signal SZ1 and/or the second server time signal SZ2 occurs in the unit 42. The stored time difference ZD is used to determine the master time signal MZ. Such a determination of the master time signal MZ occurs at least when one of the server time signals SZ1 or SZ2 is not available. The availability of the two time servers 10 and 20 can be stored in a memory 54. In the shown example, the master time signal unit 40 has a transmission unit 43 for transmission of the previously determined master time signal MZ.

(5) In the present case, the master time signal MZ is transmitted to a first control device 70 as well as to a second control device 80. In addition, it is provided that the master time signal MZ is transmitted to the first time server 10. The master time signal MZ is transmitted to the first time server 10 to synchronize the first time server 10.

(6) In the present case, the master time signal unit 40 has a memory unit 50 with a plurality of sub-memories 51-56. In the memory 51, the first server time signals SZ1 of the first time server 10 are stored. In the memory 52, on the other hand, the second server time signals SZ2 of the second time server 20 are stored. As already mentioned earlier, in the memory 53, the time difference ZD is stored. In the memory 54, data with respect to server availability can be stored. The memory 55 is the memory for the weights W. Thus, weights W of the first time server 10 as well as weights W of the second time server 20 are stored in the memory 55. In the memory 56, the master time signal(s) MZ are stored.

(7) In the present case, the first time server 10 is a vehicle clock. Thus, after the master time signal MZ has been determined, it can be transmitted to the vehicle clock. The second time server 20 is the back-end of the vehicle. Also shown is a third time server 30 to represent the random number of time servers and time server signals SZ3 to be transmitted.

(8) The master time signal MZ is transmitted to a control device 70, which in the shown example is a navigation device, as well as to a control device 80, which is a protocol memory in terms of a black box.

(9) The first time server 10 as well as the second time server 20 have assigned weights W that are used to determine the master time signal MZ. The weights W are preferably stored in the memory 55 in an encrypted fashion. The weights W can be checked and/or determined periodically or dynamically. In as far as the values with respect to the weights W of the first time server 10 and/or the second time server 20 are changed, they are stored again in the memory 55. This is done by way of overwriting the value in the memory 55. The check/determination of a weight W is preferably done when manipulation attempts, time leaps and/or transmission failures are found at the first and/or second time server 10/20.

(10) In the present case, it can be assumed that the second time server (back-end) 20 is assigned a higher weight W than the first time server (vehicle clock) 10. With a back-end, a weighting of up to 100% can be assumed.

(11) In a calibration step, the master time signal MZ can be received from the back-end and/or the second time server 20. The calibration unit 44 thus receives the second server time signal SZ2 from the second time server 20, which is to say the back-end, and stores the master time signal MZ in the memory 56. In the performed calibration step, the master time signal MZ, which in the calibration step corresponds to the second server time signal SZ2, is compared with the first server time signal SZ1 of the first time server 10. The calibration unit 44 determines the weight W of the first time server 10 as a function of the time difference ZD determined between the master time signal MZ and the first server time signal SZ1. As far as the weight W of the first time server 10 is equal to the weight W stored in the memory 55 in the comparison, the newly determined weight W does not have to be stored in the memory 55. If the weight W has changed, the newly determined weight W is stored in the memory 55 so that the initial weight W is overwritten, for example.

(12) The check and/or determination of a weight W with respect to the first time server 10 preferably occurs when a manipulation attempt, a time leap and/or a transmission failure can be found on the time server 10, which is to say the vehicle clock.

(13) Optionally, the system according to the invention can furthermore include a signature unit 45 and/or a counter 46. With the help of the signature unit 45, the determined master time signal MZ can be provided with a signature Si. Using such a signature, for example, the control device 70 can determine whether the master time signal MZ was manipulated. In addition, it is possible that the master time signal MZ is stored with a signature in the memory 56.

(14) Additionally or alternatively, it may be provided that the master time signal unit 40 includes a counter unit 46. The counter unit 46 provides the determined master time signal MZ with a counter n, wherein this is possible for the master time signal MZ, as well as for the master time signal MZ+Si provided with a signature Si.

(15) The recipient of the master time signal MZ+Si+n, which is to say the first time server 10, the control device 70 and/or the control device 80, can determine by way of the value of the counter n whether the master time signal was transmitted manipulation-free according to a continually increasing counter value. If the signature Si is erroneous, the counter value n remains the same and/or the counter value n decreases, it can be assumed that there was a manipulation attempt with respect to the transmitted master time signal MZ+Si+n.

LIST OF REFERENCE SYMBOLS

(16) 10 First time server 20 Second time server 30 Third time server 40 Master time signal unit 41 Comparer 42 Determination unit 43 Transmission unit 44 Calibration unit 45 Signature unit 46 Counter unit 50 Memory 51 Memory of first server time signal SZ1 52 Memory of second server time signal SZ2 53 Memory of time difference ZD 54 Memory of server availability 55 Memory weight W 56 Memory master time signal MZ 70 Control device 80 Control device SZ1 First server time signal SZ2 Second server time signal SZ3 Third server time signal MZ Master time signal ZD Time difference W Weight Si Signature n Counter

(17) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.