Identification system for verifying an authorization to access an object or to use an object, particularly a motor vehicle

• US 20040000986A1
• Filed: 06/30/2003
• Published: 01/01/2004
• Est. Priority Date: 12/29/2000
• Status: Active Grant

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Ott, Albert
• Granted Patent: US 7,098,769 B2
• Time in Patent Office: Days
• US Class Current: 340/5.2
• CPC Class Codes: G01S 13/84 for distance determination by phase measurement
• CPC Class Codes: G07C 2009/00412 the transmitted data signal being encrypted
• CPC Class Codes: G07C 2009/00793 by Hertzian waves
• CPC Class Codes: G07C 2209/63 Comprising locating means for detecting the position of the data carrier, i.e. within the vehicle or within a certain distance from the vehicle
• CPC Class Codes: G07C 9/00309 operated with bidirectional data transmission between data carrier and locks

Abstract

An identification system is disclosed in which an interrogation signal is emitted on the side of the object, the signal having a carrier frequency which is modified in sections. A mobile encoder (20) encodes the interrogation signal and produces a response signal which is sent back to the object (10). The response signal is mixed with the interrogation signal and decoded in an evaluation unit (14-16) on the side of the object. The distance (d) between the encoder (20) and the object (10) is then determined by means of Fourier transformation (16).

Claims

1. Identification system for verifying an authorization to access an object or to use an object, particularly a motor vehicle, comprising:

a send and receive unit disposed on the object side which transmits an interrogation signal with section-wise modified carrier frequency in modulated form according to a sequence,

a mobile encoder which generates a response signal by sending back the received sequence in encrypted and modulated form, and

an evaluation unit on the object side which decrypts the response signal and compares it with the interrogation signal with regard to a frequency offset and which determines the distance between encoder and object as a function of the result of the comparison.

2. The identification system according to claim 1, wherein the evaluation unit is supplied with a mixed signal composed of interrogation signal and response signal and a hybrid product resulting in the process is evaluated with regard to distance.

3. The identification system according to claim 1, wherein the mobile encoder comprises a memory in which the sequence of section-wise modified carrier frequencies is buffered and with the aid of which the response signal is encrypted.

4. The identification system according to claim 1, wherein the evaluation unit comprises a decryption unit which decrypts the received response signal with regard to the sequence of the section-wise modified carrier frequencies, and a decoding unit which mixes the response signal with the interrogation signal and evaluates it with regard to the propagation time difference between the two and therefore the distance between encoder and object.

5. The identification system according to claim 1, wherein the interrogation signal is transmitted as a broadband signal modulated with section-wise modified carrier frequencies in the frequency range greater than 100 MHz.

6. The identification system according to claim 1, wherein the evaluation unit comprises a Fourier transformer with the aid of which the distance is determined.

7. Identification system for verifying an authorization to access an object or to use an object, in particular a motor vehicle, comprising:

a send and receive unit disposed on the object side which transmits a first interrogation signal with section-wise modified carrier frequency according to a sequence and a second interrogation signal in modulated form at a different carrier frequency,

a mobile encoder which correlates the first and the second interrogation signal and sends back a response signal, and

an evaluation unit on the object side which compares the response signal together with an encoded reference signal with regard to a frequency offset and determines the distance between encoder and object as a function of the result of the comparison.

8. Method for verifying an authorization to access an object or to use an object, particularly a motor vehicle, comprising the steps of:

transmitting an interrogation signal with section-wise modified carrier frequency in modulated form according to a sequence,

generating a response signal by sending back the received sequence in encrypted and modulated form, and

decrypting the response signal and comparing it with the interrogation signal with regard to a frequency offset and determining the distance between encoder and object as a function of the result of the comparison.

9. The method according to claim 8, further comprising the step of providing a mixed signal composed of interrogation signal and response signal and evaluating a hybrid product resulting in the process with regard to distance.

10. The method according to claim 8, further comprising the step of buffering the sequence of section-wise modified carrier frequencies and encrypting the response signal with the aid of said sequence.

11. The method according to claim 8, further comprising the steps of:

decrypting the received response signal with regard to the sequence of the section-wise modified carrier frequencies,

mixing the response signal with the interrogation signal, and

evaluating the response signal with regard to the propagation time difference between the two and therefore the distance between encoder and object.

12. The method according to claim 8, further comprising the step of transmitting the interrogation signal as a broadband signal modulated with section-wise modified carrier frequencies in the frequency range greater than 100 MHz.

13. The method according to claim 8, further comprising the step of determining the distance by performing a Fourier transformation.

14. Method for verifying an authorization to access an object or to use an object, in particular a motor vehicle, comprising the steps:

transmitting a first interrogation signal with section-wise modified carrier frequency according to a sequence and a second interrogation signal in modulated form at a different carrier frequency,

correlating the first and the second interrogation signal and sending back a response signal, and

comparing the response signal together with an encoded reference signal with regard to a frequency offset and determining the distance between encoder and object as a function of the result of the comparison.