Acoustic surface wave radio frequency tag with high coding capacity

Abstract

The invention relates to an acoustic surface wave radio frequency tag which is characterized in that an interdigital transducer is manufactured on a piezoelectric substrate, and a series of reflecting gratings are arranged behind the interdigital transducer; the reflecting gratings can be arranged in one row or multiple rows; the time interval from the interdigital transducer to the reflecting pulse of the first reflecting grating is set as a blind area, and the position of the first reflecting grating is determined according to the size of the blind area; in order to correct the influence ofthe uncertain environment temperature, two or three reflecting gratings are arranged generally, wherein one or two phase delay time intervals among the reflecting gratings are accurately known under the specific standard temperature and are constants irrelevant to code values, and each phase delay time interval between other adjacent reflecting gratings is used for representing different tag codes; and the phase delay time intervals among the reflecting gratings are limited, are not definitely used for directly representing code values, and can be possibly used for self-checking, self-correction or anti-collision and other purposes of coded data. The invention can obtain maximal coding capacity under the same information space and frequency bandwidth.

Description

technical field [0001] This patent relates to surface acoustic wave radio frequency tags. Background technique [0002] Radio Frequency Identification (RFID, Radio Frequency Identification) technology is a technology that applies non-contact tags, which automatically identify target objects and obtain relevant data through radio frequency signals. It is an important practical technology to adapt to the development of information technology and information society. It is used in intelligent management in many fields such as automatic toll collection of expressways, logistics management, automatic parcel sorting of postal aviation, storage and book management, animal husbandry monitoring and management, and vehicle anti-theft. It has great application prospects. In order to achieve a single tag number for any item in the world, the tag needs to implement 64-bit, 96-bit or even 128-bit encoding. [0003] RFID tags using Surface Acoustic Wave (SAW) technology is a radio freque...

AI Technical Summary

Problems solved by technology

[0013] (2) Although grouping is not the main feature of U.S. Patent No. 6,966,493, if the 12 groups described in the patent claims are realized, it is necessary to ensure that there is an interval dead zone between two groups that cannot be used for encoding in physical space. This greatly reduces the encoding capacity

As the number of slots increases, the farther the reflective grating position deviates from the reference reflective grating position, the greater the measurement error, thereby reducing reliability, or having to reduce the space size of each group

[0015] (4) The method of temperature compensation is not given

Assuming that the carrier phase of a reflected echo has the fourth quadrant of (+I, -Q) given in the embodiment, after the process of design, label production and actual demodulation, the demodulated phase cannot exceed the fourth quadrant anyway. Four-quadrant range, otherwise it will cause label decoding error

However, the change of the working temperature of the label often makes all the measured phases of the reflected signal deviate from the design value.

As the temperature range increases, if the temperature compensation is not set or the temperature compensation is not set properly, it may cause the measured phase to exceed the fourth quadrant, resulting in bit errors

As a result, on the one hand, it is necessary to set a sufficiently large distance between the slots in its design so as to drastically reduce the different code capacity; on the other hand, its usable temperature range is greatly limited

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