Method for determining the distance between a base station and a mobile object, in addition to a base station and identification system for a method of this type

• US 20050099333A1
• Filed: 09/15/2004
• Published: 05/12/2005
• Est. Priority Date: 12/20/2002
• Status: Active Grant

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Gila, Janos, Konrad, Wolfgang, Renner, Alexander
• Granted Patent: US 7,205,931 B2
• Time in Patent Office: Days
• US Class Current: 342/118
• CPC Class Codes: G01S 13/348 using square or rectangular modulation, e.g. diplex radar for ranging over short distances
• CPC Class Codes: G01S 13/74 Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
• CPC Class Codes: G01S 13/75 using transponders powered from received waves, e.g. using passive transponders , or using passive reflectors
• CPC Class Codes: G01S 7/2886 using I/Q processing

Abstract

A method for determining the distance between a base station (SLG) and a mobile object (DT1-DT3). A HF carrier frequency and an offset frequency (df) are predetermined for a QAM modulation. The HF carrier frequency is increased and decreased by the offset frequency in sequence over time in such a way that the HF carrier base frequencies (fo+df, fo−df) resulting in an HF carrier signal (TS) thus modulated exhibit an identical phase when the frequency is changed. The HF carrier signal is subsequently transmitted and simultaneously mixed (MIX) with an HF carrier signal (RS) that has been backscattered by the mobile object to obtain a carrier phase signal (PS). The corresponding carrier phase (PH1, PH2) for the two HF carrier base frequencies is determined in sequence over time. The difference (dPH) between these phases is used to calculate the distance between the base station and the respective mobile object.

Claims

1. Method for determining the distance between a base station and a mobile object, the method comprising:

a) defining an HF carrier frequency and an offset frequency df for IQ modulation;

b) sequentially increasing and decreasing the HF carrier frequency fo by the offset frequency df over time to generate two HF carrier base frequencies fo+df and fo−

df that are modulated in a carrier signal such that the HF carrier base frequencies have identical phases;

c) sequentially transmitting the HF carrier signal and mixing with a backscattered HF carrier signal to form a carrier phase signal;

d) sequentially determining phases for the two HF carrier base frequencies fo+df and fo−

df in the carrier phase signal over time, and

e) using a difference between phases of the two carrier base frequencies fo+df and fo−

df to determine the distance between the base station and the mobile object.

2. The method of claim 1, wherein the HF carrier frequency fo is changed between two distance determinations.

3. The method of claim 1, wherein the offset frequency df is changed between two distance determinations.

4. The method of claim 1, wherein multiple distance determinations are made and subsequently averaged.

5. The method of claim 1, wherein the base station is a read/write device and the mobile object is a mobile data memory.

6. The method of claim 5, wherein the distance is determined in a transmission channel between the read/write device and the mobile data memory.

7. The method of claim 6, wherein the transmission channel has a plurality of sub-channels.

8. The method of claim 6, wherein the transmission channel corresponds to a notification channel of the ISO 18000-4-MOD3 Standard.

9. The method of claim 8, wherein the sub-channels in the transmission channel correspond to R2-channels in the notification channel of the ISO 18000-4-MOD3 Standard.

19. The base station of claim 1, wherein the base station is a read-write device.

10. An identification system comprising:

a read-write device;

a mobile data memory operable to be attached to a transported object to record at least one of object-specific status data and object-specific process data,

the read-write device further including;

a transceiver and an electronic signal processor,

the transceiver further including;

a digital IQ modulator,

a transceiver antenna operable to transmit a carrier signal having a carrier frequency fo increased by an offset frequency df and additionally decreased by the offset frequency df such that the two frequencies fo+df and fo−

df in the carrier signal have identical phases, the transceiver antenna further operable to receive a backscattered carrier signal, and

a mixer operable to form a carrier phase signal by mixing the carrier signal and the backscattered carrier signal;

an electronic signal processor operable to determine the distance between the base station and the mobile object using a phase difference between the two frequencies fo+df and fo−

df in the carrier phase signal.

11. The system of claim 10, wherein the HF carrier frequency fo is changed between two distance determinations.

12. The system of claim 10, wherein the offset frequency df is changed between two distance determinations.

13. The system of claim 10, wherein multiple distance determinations are made and subsequently averaged.

14. The system of claim 10, wherein the read/write device is a stationary base station.

15. A base station comprising:

a transceiver and

an electronic signal processor,

the transceiver further including;

a digital IQ modulator,

a transceiver antenna operable to transmit a carrier signal having a carrier frequency fo both increased by an offset frequency df and decreased by the offset df such that the two frequencies fo+df and fo−

df in the carrier signal have identical phases, the transceiver antenna further operable to receive a backscattered carrier signal, and

a mixer operable to form a carrier phase signal by mixing the carrier signal and the backscattered carrier signal;

an electronic signal processor operable to determine the distance between the base station and the mobile object using a phase difference between the two frequencies fo+df and fo−

df in the carrier phase signal.

16. The base station of claim 15, wherein the HF carrier frequency fo is changed between two distance determinations.

17. The base station of claim 15, wherein the offset frequency df is changed between two distance determinations.

18. The method of claim 15, wherein multiple distance determinations are made and subsequently averaged.

20. A method of determining a distance between a base station and a mobile object, the method comprising:

a) transmitting a carrier signal with two frequencies f+df and f−

df and identical phases from the base station to the mobile object;

b) mixing the carrier signal with a signal backscattered from the mobile object to form a carrier phase signal; and

c) determining the distance based on a phase difference between f+df and f−

df in the carrier phase signal.