WO2003063370A1

WO2003063370A1 - Method and device for generating a high frequency multiple carrier signal

Info

Publication number: WO2003063370A1
Application number: PCT/DE2003/000132
Authority: WO
Inventors: Janos Gila; Olaf Albert
Original assignee: Siemens Aktiengesellschaft
Priority date: 2002-01-25
Filing date: 2003-01-17
Publication date: 2003-07-31
Also published as: EP1468500A1; CA2474361A1

Abstract

The invention relates to a method and a circuit (SA) for generating a high frequency multiple carrier signal (TS) from two carrier signals (S1,S2) having, respectively, a carrier frequency (f1,f2). The invention also relates to a writing/reading device (SLG) containing said circuit, in addition to an identification system (IDS) containing at least one writing/reading device and a mobile data memory (DT1-DT3). One advantage thereof is that high linear and expensive HF-amplifiers (V1,V2), which have high current consumption and generate high amounts of heat, are no longer necessary in order to achieve a sufficiently high minimum attenuation (GW) between the carrier frequencies and the adjacent intermodulation frequency parts (2f2-f1,2f1-f2,..) in the multiple carrier signal. Another advantage of said invention is that the reliability and service life of the circuit increases and the use of a downstream HF filter can be dispensed with.

Description

description

METHOD AND DEVICE FOR GENERATING A HIGH-FREQUENCY MULTIPLE CARRIER SIGNAL

The invention relates to a method and a circuit arrangement for generating a high-frequency multi-carrier signal from at least two carrier signals, each with a carrier frequency. The invention further relates to a read / write device with the circuit arrangement and an identification system with at least one read / write device and at least one mobile data memory.

Identification systems are known as prior art which contain one or more stationary read / write devices which exchange data with mobile data memories in a contactless manner via a radio transmission-based data transmission link. Systems of this type are used in technical facilities in which a large number of objects or goods have to be moved as quickly and freely as possible. The objects can be of various types, e.g. Parcels in a shipping facility, assembly parts in a production facility, luggage in a transport system and much more.

An example of such an identification system is described in the ISO / IEC JTC 1 / SC 31 WG4 standard draft with the title “Radiofrequency Identification Standard for Item Management - Air Interface, (WD 18000) from August 15, 2001.

The draft standard provides for the write / read reader to query for the presence of a mobile data memory in the detection area. For this purpose, the read / write device sends out an unmodulated first carrier signal with a fixed carrier frequency, for example with a frequency of 2.45 GHz. This carrier signal can passively from a mobile data memory located in the reception area, for example through so-called "back scattering" are sent back to the read / write device.

Irrespective of this, the mobile data memory modulates the impedance of a transmit / receive antenna integrated in the mobile data memory in cyclic sequences with a significant recognition sequence for identifying the mobile data memory in a read / write device. If the first carrier signal that has been sent back and modulated with the recognition sequence can be received by the read / write device and has been recognized as valid, then this creates another carrier signal. When the second carrier signal is applied, the write / read reader t signals the mobile data memory that a data transmission will follow. The second carrier signal is therefore modulated for data transmission. This carrier signal is from the mobile

Data storage is queried cyclically and at short intervals for existence. If this is the case, the mobile data storage device can switch on the data receiver for the subsequent data transmission.

The frequency of the second carrier signal is advantageously shifted from the first carrier frequency by a fixed frequency amount. In the above For example, a standard frequency spacing of 10.6496 MHz is proposed. The signal generation of the two carrier signals with such a small carrier frequency spacing of approximately 10.7 MHz at a carrier frequency of approximately 2.45 GHz is, however, technically complex. For example, in the above 2.5 GHz ISM frequency band to take into account the relevant radio regulations. These may require a minimum attenuation of the frequency ranges adjoining the two carrier frequencies in order to avoid interference with useful signals. A common value for this minimum attenuation is e.g. 40 dB or - based on the maximum absolute power output - e.g. a value of -30 dBm.

In known circuit arrangements, the individual high-frequency carrier frequencies are each generated by a signal generator. creates and combined by means of an RF combiner or RF divider known for example from microwave technology or satellite technology to form a multiple carrier signal. The multiple carrier signal is then amplified to the necessary output power by a power amplifier and fed to an antenna for radiation. Alternatively, the multiple carrier signal can also be fed into a transmission line, such as a coaxial line.

For example, in the technical manual entitled "Satellite Communications *" by Dennis Roddy, Second Edition, McGraw-Hill 1995, ISBN 0-07-053370-9, a known circuit arrangement is described on pages 209f. A large number of microwave carrier signals are combined by an RF combiner (Co biner). The combined multiple carrier signal is then amplified by means of a power amplifier and fed to a satellite antenna for radiation.

As a rule, when using conventional RF amplifiers in the known circuit arrangement, high-frequency interference frequency components would occur in the amplified multiple carrier signal. This would be the case in particular if the individual carrier frequencies in the frequency spectrum were particularly “close to ¹ ^{” 1} . The cause of these interference frequency components, which are referred to below as intermodulation frequency components, is the non-ideal transmission behavior of the RF amplifiers used. Although these intermodulation frequency components can be significantly reduced by using technically high-quality, that is to say in particular highly linear, RF amplifiers, this is complex and cost-intensive. In addition, the use of the highly linear RF amplifiers results in high power consumption with appropriate heat development and a large space requirement. However, it is often still necessary to add complex and space-intensive RF filters in order to reduce the intermodulation frequency components to a sufficient level. The object of the invention is to provide a circuit arrangement for generating a high-frequency multi-carrier signal, which allows the use of less high-quality circuit components and the elimination of any downstream HF filter measures.

Another object is to provide a circuit arrangement with a reduced space and current requirement.

Finally, it is the object of the invention to provide a write / read reader with the circuit arrangement and an identification system with the write / read reader.

The object of the invention is achieved with a method for generating a high-frequency multi-carrier signal from at least two carrier signals, each with a carrier frequency, the carrier signals generated being amplified separately at the high-frequency level and then combined to form the multi-carrier signal. The carrier signals can be generated in such a way that the respective carrier frequencies have a predeterminable frequency spacing from one another. A ratio of the frequency spacing to an adjacent carrier frequency of less than 1: 100 can be specified. The carrier signals can also be generated in such a way that at least one carrier frequency has at least one side band. Carrier frequencies of at least 300 MHz can also be generated. The method can be operated in an ISM frequency band of 2.45 GHz, 5.6 GHz or in a UHF frequency band of the ISM frequency band.

The object is further achieved with a circuit arrangement for generating a high-frequency multiple carrier signal from at least two carrier signals, each with a carrier frequency. This has, in each case a signal generator for generating the carrier signals, in each case an RF amplifier which is connected downstream of the respective signal generator, and an HF combiner for forming the multi-carrier signal at a signal output which is connected downstream of the RF amplifiers. at In the circuit arrangement, the signal generators can be set so that the respective carrier frequencies have a predeterminable frequency spacing from one another. The ratio of the predeterminable frequency spacing to an adjacent carrier frequency can be less than 1: 100. In the circuit arrangement, the signal generators can also be set such that at least one carrier frequency has at least one side band. In the circuit arrangement, the RF amplifiers and the RF combiner have electrical characteristics which are matched to one another in such a way that intermodulation frequency components have a minimum attenuation when the multicarrier signal is formed compared to the carrier frequencies. A nonlinearity or a distortion factor of an RF amplifier can serve as a tunable electrical characteristic value. A common mode suppression of the inputs of the HF combiner can serve as a tunable electrical characteristic. Furthermore, the minimum attenuation can be 40 dB or, based on the maximum absolute power output, -30 dBm. Furthermore, the carrier frequencies generated by the signal generators can be at least 300 MHz. With the circuit arrangement, the HF combiner can be a Wilkinson

Be a divider or a branch line divider. The circuit arrangement can be operated in an ISM frequency band of 2.45 GHz, 5.6 GHz or in a UHF frequency band of the ISM frequency band.

Furthermore, the object is achieved with a write / read reader t for data transmission with at least one mobile data memory which has the circuit arrangement.

Finally, the object is achieved with an identification system with at least one such write / read reader and with at least one mobile data memory. The identification system can be based on an ISOZIEC 18000 standard.

This has the advantage that no highly linear and expensive RF amplifiers, which also have high power consumption and high heat development, are required. in order to achieve a sufficiently high attenuation between the carrier frequencies and the adjacent intermodulation frequency components in the multi-carrier signal.

This further advantageously increases the reliability and service life of the circuit arrangement.

Furthermore, it is advantageously possible to dispense with a downstream complex RF filter in order to dampen any impermissibly high intermodulation frequency components that may be present in the multiple carrier signal.

Finally, it is a further advantage to match the circuit arrangement according to the invention by means of a suitable combination of the electrical characteristic values of the RF amplifier and the RF combiner in such a way that the circuitry complexity for a sufficient minimum attenuation is minimal.

This is explained in more detail in the following two figures. It shows

1 shows an example of the construction of an identification system with a write / read reader and with three mobile data memories according to the invention,

2 shows an example of a circuit arrangement according to the invention for generating a multi-carrier signal, and

FIG 3-5: exemplary frequency spectra of the carrier signals and the multi-carrier signal generated.

1 shows an example of the construction of an identification system IDS with a stationary write / read reader SLG according to the invention, which exchanges data with three mobile data memories DT1-DT3 by way of example. For illustration purposes the movement directions R1-R3 associated with the mobile data memories DT1-DT3 are also shown by way of example. The write / read reader SLG and the mobile data memories DT1-DT3 have suitable transmit / receive antennas ANT, SEA for sending and receiving the data. In the example of the figure, the circuit arrangement SA according to the invention, which is connected to the transmit / receive antenna ANT for data transmission, can also be seen as part of the write / read reader SLG.

2 shows an example of a circuit arrangement SA according to the invention for generating a multicarrier signal TS with two RF amplifiers VI, V2 and an RF combiner HF. Known HF combiners HF are e.g. the Wilkinson divider or the branch line divider. In the left part of the figure there are two signal generators G1, G2, e.g. Quartz oscillators or RF synthesizers, which are used to generate a carrier signal S1, S2, each with a carrier frequency fl, f2.

According to the invention, each carrier signal S1, S2 is separately amplified to the desired power by means of a downstream RF amplifier VI, V2 before it is fed to an HF combiner HF. As a result, intermodulation with the respective carrier frequencies fl, f2 as in the prior art is not possible. The downstream HF combiner HF has an input E1, E2 for combining the amplified carrier signals VS1, VS2. Finally, the merged multiple carrier signal TS is available at a signal output A of the HF combiner HF. As in the example in FIG. 2, this can then be used to feed the transmit / receive antenna ANT.

As explained at the beginning, highly linear RF amplifiers are necessary for a circuit arrangement according to the prior art in order to significantly reduce the occurrence of intermodulation frequency components. The reason for this is in particular the non-linearity EK1 of the RF amplifier or the distortion factor EK2 as a technical characteristic of the RF amplifier. The inter odulation Frequency components arise at discrete points in the frequency spectrum of the multicarrier signal and have high interference levels there. Starting from the two carrier frequencies fl, f2, these then appear more damped in the same carrier frequency spacing dF for increasing and decreasing frequencies (see FIG. 5). The level of the interference levels of the intermodulation frequency components is lower, the lower the non-linearity EK1 or the harmonic distortion EK2 of the RF amplifier used.

As a result, it is also advantageously possible to use technically simple and energy-saving HF amplifiers HF with lower demands on the technical characteristics, such as non-linearities EK1 or distortion factor EK2. The space requirement and the heat development are reduced considerably due to the power loss of the RF amplifiers VI, V2.

Furthermore, it is advantageously possible to dispense with a complex RF filter connected downstream, in order to dampen any impermissibly high intermodulation frequency components present in the multiple carrier signal TS.

Intermodulation frequency components can consequently only arise in the HF combiner HF by intermodulation of the amplified carrier signals VS1, VS2 present at the inputs E1, E2. A signal separation at the inputs E1, E2 on the HF combiner is decisive for a possible generation. However, due to technical reasons, infinite signal separation cannot be achieved, so that HF intermodulation frequency components would also appear in the HF combiner. However, because of the simple structure of the HF combiner HF with its exclusively passive components, these would only arise to a small extent. Above all, compliance with the component tolerances of the ohmic characteristic impedance and the accuracy of the geometrical dimensions of the waveguides is decisive. These determine the quality of the signal separation or the common mode rejection EK3 as a technical characteristic value EK3 of the signals at the input E1, E2. Compliance with the above tolerances can be achieved with relatively little effort.

With a suitable selection of the RF amplifiers VI, V2 and the HF combiner HF for the circuit arrangement SA according to the invention, an optimized solution is advantageously possible, taking into account the relevant technical characteristics EK1-EK3. This can take place in such a way that a required minimum limit value GW for attenuation to the intermodulation frequency components can advantageously be maintained without additional HF filtering measures.

3-5 show exemplary frequency spectra F1, F2, FV1, FV2, FA of the above-described carrier signals S1, S2 and the generated multiple carrier signal TS for better understanding. The respective carrier frequencies fl, f2 are entered with the corresponding signal levels P1, P2 of the carrier frequencies fl, f2, the carrier frequency fl additionally having side bands SB1, SB2 due to data modulation. Furthermore, the abscissa provided with the reference symbol f represents the frequency and the ordinate provided with the reference symbol p represents the level of the respective signals S1, S2, TS.

3 shows the frequency spectrum F1, FV1 of the carrier signal SI generated by the signal generator Gl as an example, and the amplified carrier signal VS1. Because there is no possibility of intermodulation with the carrier frequency f2, the frequency spectra F1, FV1 are almost identical. Because of this, the two frequency spectra F1, FV1 are shown in a common figure. FIG. 4 represents the frequency spectrum F2, FV2 of the carrier signal S2 and the amplified carrier signal VS2 analogously to the carrier signal SI, with no data modulation taking place.

5 shows an example of the frequency spectrum FA of the output signal A of the HF combiner HF after combining the two amplified carrier signals VS1, VS2 to form the multiple carrier signal TS. The carrier frequencies fl, f2 already described at the beginning with the carrier frequency spacing dF and the intermodulation frequency components 2f2-f1, 2fl-f2, .. can be seen as decreasing continuations in both directions of the abscissa f.

The interference levels P3, P4, P7, P8 of the intermodulation frequency components 2f2-f1, 2fl-f2,... Are shown by dashed lines for a circuit arrangement according to the prior art. It can be seen that the exemplary interference levels P3, P4 are not sufficiently attenuated with respect to the two carrier frequencies fl, f2. Further HF filter measures would be necessary here.

In contrast, the intermodulation frequency components 2f2-fl, 2fl-f2, .. when using the circuit arrangement according to the invention advantageously have lower interference levels P5, Pβ at the same frequencies. It can be seen that the interference levels P5, P6 have a greater attenuation than the required minimum attenuation GW compared to the two carrier frequencies fl, f2.

Claims

claims

1. A method for generating a high-frequency multi-carrier signal (TS) from at least two carrier signals (S1, S2), each with a carrier frequency (fl, f2), the carrier signals (S1, S2) being amplified separately at the radio-frequency level and then to the multi-carrier signal (TS ) are brought together.

2. The method according to claim 1, wherein the carrier signals (S1, S2) are generated such that the respective carrier frequencies (fl, f2) have a predeterminable frequency spacing (dF) from one another.

3. The method according to claim 2, wherein a ratio of the frequency spacing (dF) to an adjacent carrier frequency

(fl, f2) of less than 1: 100 is specified.

4. The method according to any one of the preceding claims, wherein the carrier signals (S1, S2) are generated so that at least one carrier frequency (fl, f2) has at least one side band (SB1, SB2).

5. The method according to any one of the preceding claims, wherein carrier frequencies (fl, f2) of at least 300 MHz are generated.

6. The method according to any one of the preceding claims for operation in an ISM frequency band of 2.45 GHz.

7. The method according to any one of claims 1 to 5 for operation in an ISM frequency band of 5.6 GHz.

8. The method according to any one of claims 1 to 5 for operation in a UHF frequency band of the ISM frequency band.

9. Circuit arrangement (SA) for generating a high-frequency multiple carrier signal (TS) from at least two carrier signals (S1, S2), each with a carrier frequency (fl, f2), which has

a) a signal generator (Gl, G2) each for generating the carrier signals (S1, S2),

b) an RF amplifier (VI, V2), which is connected downstream of the respective signal generator (G1, G2), and

c) an RF combiner (HT) for forming the multi-carrier signal (TS) at a signal output (A), which is connected downstream of the RF amplifier (VI, V2).

10. Circuit arrangement (SA) according to claim 9, wherein the signal generators (G1, G2) are set such that the respective carrier frequencies (fl, f2) have a predeterminable frequency spacing (dF) from one another.

11. The circuit arrangement (SA) according to claim 10, wherein the ratio of the predeterminable frequency spacing (dF) to an adjacent carrier frequency (fl, f2) is less than 1: 100.

12. Circuit arrangement (SA) according to one of claims 9 to 11, wherein the signal generators (Gl, G2) are set such that at least one carrier frequency (fl, f2) has at least one side band (SB1, SB2).

13. Circuit arrangement (SA) according to one of claims 9 to 12, wherein the RF amplifier (VI, V2) and the RF combiner (HF) have coordinated electrical characteristics (EK1-EK3) such that intermodulation frequency components (2f2-f1 , 2fl-f2, ..) have a minimum attenuation (GW) compared to the carrier frequencies (fl, f2) when the multiple carrier signal (TS) is formed.

14. Circuit arrangement (SA) according to claim 13, wherein a non-linearity (EK1) of an RF amplifier (VI, V2) serves as a tunable electrical characteristic value.

15. Circuit arrangement (SA) according to claim 13, wherein a harmonic distortion (EK2) of an RF amplifier (VI, V2) serves as a tunable electrical characteristic value.

16. Circuit arrangement (SA) according to claim 13, wherein a common mode rejection (EK3) of the inputs (E1, E2) of the RF combiner

(HF, WT) serves as a tunable electrical characteristic.

17. Circuit arrangement (SA) according to one of claims 13 to

16, where the minimum attenuation (GW) is 40dB.

18. Circuit arrangement (SA) according to one of claims 13 to

17, the carrier frequencies (fl, f2) generated by the signal generators (G1, G2) being at least 300 MHz.

19. Circuit arrangement (SA) according to one of claims 9 to 18, wherein the HF combiner (HF) is a Wilkinson divider.

20. Circuit arrangement (SA) according to one of claims 9 to 18, wherein the HF combiner (HF) is a branch line divider.

21. Circuit arrangement (SA) according to one of claims 9 to 20, which is operated in an ISM frequency band of 2.45 GHz.

22. Circuit arrangement (SA) according to one of claims 9 to 20, which is operated in an ISM frequency band of 5.6 GHz.

23. Circuit arrangement (SA) according to one of claims 9 to 20, which is operated in a UHF frequency band of the ISM frequency band.

24. Write / read reader (SLG) for data transmission with at least one mobile data memory (DT1-DT3), which has a circuit arrangement (SA) according to one of Claims 9 to 23.

25. Identification system (IDS) with at least one write / read reader (SLG) according to claim 24 and with at least one mobile data memory (DT1-DT3).

26. Identification system (IDS) according to claim 25, which is based on an ISOZIEC 18000 standard.