# Patent

## Title
Method and circuit for transmitting a data-modulated high-frequency data signal from a transmitter to a receiver having a simplified receiver architecture

## Abstract

A method and circuit for transmitting a data-modulated high-frequency data signal fC from a transmitter to a receiver, for transmitting data between a read-write device (RWD) and at least one mobile data memory (MDM) in an identification system that has a number of mobile data memories (MDM) which are placed on objects and which are provided for detecting object-specific status data and/or process data. Such an identification system is particularly useful, e.g., in a shipping, transport and/or manufacturing system of the individual objects. In addition to the transmitted high frequency data signal fC, a further high-frequency data signal fS is transmitted, which serves to convert the frequency and/or to modulate the carrier code of the high-frequency data signal fC.

## Background
This is a Continuation of International Application PCT/DE00/04398, with an international filing date of Dec. 11, 2000, which was published under PCT Article 21(2) in German, and the disclosure of which is incorporated into this application by reference.


FIELD OF AND BACKGROUND OF THE INVENTION
The invention relates to a method for transmitting a data-modulated high-frequency data signal from a transmitter to a receiver having a simplified receiver architecture, and to a circuit, identification system and overall system utilizing such a method.
Circuits for transmitting a data-modulated high-frequency data signal from a transmitter to a receiver in which an oscillator and a PLL synthesizer are provided to shift the received high-frequency data signal to a lower frequency band for further processing are known in the art. Such circuits have a complex structure and their power consumption is high. They are therefore not suitable for mobile data memories, e.g., those used for transmitting data between a read/write device and at least one mobile data memory in an identification system having a plurality of mobile data memories which are attached to objects and which are provided for detecting object-related status and/or process data of the individual objects, e.g., in a shipping, transport and/or manufacturing system.
OBJECTS OF THE INVENTION
One object of the invention is to provide a circuit for transmitting a data-modulated high-frequency data signal from a transmitter to a receiver, in which the receiver has a simpler structure and consumes less power than is the case in conventional devices. Another object is to provide a method for operating such a circuit.
SUMMARY OF THE INVENTION
With respect to the method, according to one formulation of the invention, this and other objects are attained by: transmitting a data-modulated high-frequency data signal fC in a given band range; transmitting an additional high-frequency data signal fS together with the high-frequency data signal fC in a band range different from the given band range; amplifying the high-frequency data signals fC and fS; mixing the high-frequency data signals fC and fS to generate a data-modulated intermediate-frequency data signal fIF; and data modulating the intermediate frequency data signal fIF. For the circuit, according to a further formulation of the invention, this and other objects are attained by: an antenna receiving both a high-frequency data signal fC and an additional high-frequency data signal fS; amplifiers amplifying, respectively, the high-frequency data signals fC and fS; and a mixer mixing the high-frequency data signals fC and fS, to generate a data-modulated intermediate-frequency data signal fIF.
The method, according to the invention as defined above, provides that, in addition to the data-modulated high-frequency data signal, another high-frequency data signal is transmitted, which serves for frequency shifting and/or carrier code demodulation. Thus, it is no longer necessary to generate separate signals in the receiver for this purpose, and the corresponding receiver components are eliminated, including, e.g., the PLL synthesizer and the oscillator.
After amplification of the two high-frequency data signals, the signals are mixed and a data-modulated intermediate frequency data signal is generated and subsequently data-demodulated.
To increase the interference immunity of the receiver of the data-modulated high-frequency data signal, this signal can also be provided with a carrier code, e.g., a spread spectrum code. In this case it can be advantageous to separate the two transmitted high-frequency data signals prior to amplification and, if necessary, to amplify them differently.
In both variants of the method—with or without separation prior to amplification—the two high-frequency data signals may be mixed in a mixer in which the frequencies are converted and correlated.
In the circuit according to the above formulation of the invention, first an antenna is provided for jointly receiving the data-modulated high-frequency data signal as well as the additional high-frequency data signal. Further, an amplifier is used to amplify each of the two high-frequency data signals and a mixer unit to mix the high-frequency data signals to generate an intermediate-frequency data signal.
If the two high-frequency data signals are separated after having been received together and prior to further processing (e.g., if the high-frequency data signal is carrier-code modulated), this separation can be carried out in a filter unit, e.g., a diplexer filter.
The mixer unit for mixing the high-frequency data signals after reception and amplification to generate a data-modulated intermediate-frequency data signal, can be configured as a frequency converter/correlator mixer.



BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in greater detail by means of exemplary embodiments with reference to the drawing figures in which:
FIG. 1 is a schematic representation of a read/write device with mobile data memories located at respective distances from the read/write device;
FIG. 2 shows a circuit of a prior art receiver; and
FIG. 3 shows a circuit according to the invention with simplified receiver architecture.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows an identification system IDS that includes mobile data memories (MDM 1-3) arranged at various locations, and possibly moving, relative to a read/write device (RWD). The mobile data memories (MDM) communicate with the read/write device (RWD), preferably via radio signals, for the purpose of transferring data at least from the mobile data memories (MDM) to the read/write device (RWD).
FIG. 2 depicts a circuit of a prior art receiver for receiving a data-modulated high-frequency data signal fC (signal fC), which is received via an antenna 1 and then first passes through a filter 2 to suppress off-band interfering signals (wide-up filter). After passing through an amplifier 3, signal fC enters a mixer 4 to which a data signal fLO (signal fLO) of the local (receiver-internal) oscillator 5 is also supplied.
Signal fLO is generated in a manner known in the art by way of a phase-locked loop (PLL) by the interaction of the oscillator 5, preferably a voltage-controlled oscillator (VCO), a PLL synthesizer 6 and a frequency generator 7, controlled and monitored by a microcontroller 14.
Following mixer 4, the frequency of signal fC is converted and reduced.
Specifically, at the output of mixer 4, there is produced both a frequency sum fC+fLO and a frequency difference fC−fLO. The frequency sum is suppressed by a filter 8, which is an intermediate-frequency filter functioning as a channel filter. This produces a mixer signal fM1 with a new intermediate frequency, namely of the frequency difference fC−fLO. This intermediate frequency is then amplified in an amplifier 9 and mixed in a mixer 10 with an internal key signal fIS (signal fIS) to eliminate frequency spreading if the high-frequency data signal fC was modulated with a carrier code (e.g., a spread spectrum code). The signal fIS, together with the internal key frequency, is provided by the microcontroller 14.
Following the mixer 10, the unspread mixer signal fM2 passes through an amplifier 11, a detector 12, and a data shaper 13, to then be data demodulated and further processed in the microcontroller 14.
FIG. 3 is a schematic representation of an inventive circuit of a receiver for receiving a data-modulated high-frequency data signal fC (signal fC) from a transmitter. In addition to signal fC, another high-frequency data signal fS (signal fS) is received via antenna 1. The two signals fC and fS pass through a filter 2 to suppress off-band interference signals (wide-up filter) and an amplifier 3.
Particularly if the high-frequency data signal fC is also carrier-code modulated, e.g., as a spread spectrum signal, carrier bandpass filters 15a, 15b are provided for separating signals fC and fS. Signal fC is amplified in a carrier band amplifier 16a and signal fS in a carrier band amplifier 16b. The separately amplified signals are then again supplied to a mixer 17 in which signal fS is used to convert the frequency and demodulate the carrier code of signal fC.
At the output of the mixer 17, both the frequency sum fC+fS and the frequency difference fC−fS occur; the frequency sum is suppressed by the intermediate-frequency filter 8. Thus, a mixer signal fM3 (signal fM3), which is in an intermediate frequency position below the frequency of signal fC, leaves the intermediate frequency filter 8, while at the same time eliminating the carrier code modulation of data signal fC (“unspreading”).
Signal fM3 is data-demodulated in amplifier 11, detector 12, and data shaper 13 in the manner described with reference to FIG. 2 and is supplied to microcontroller 14 for further processing.
If signal fC is not carrier-code modulated, it is not necessary to separate the signals fC and fS in carrier band filters 15a, 15b and amplify them separately in carrier band amplifiers 16a, 16b. In this case, the two data signals fC and fS, after passing through the amplifier 3, can be amplified together and supplied to the mixer 17.
External signal fS, which is transmitted together with the signal fC, is thus used to convert the frequency of data signal fC into the intermediate frequency position and/or to unspread the data signal fC in the circuit, as shown in FIG. 3.
The inventive circuit according to FIG. 3, in contrast to the prior art circuit, requires neither an internal signal fS for carrier-code modulation of signal fC nor an internal signal fLO in the receiver. Consequently, the circuit according to FIG. 3 has a simpler configuration and consumes less power.
The above description of the preferred embodiments has been given by way of example. From the disclosure given, those skilled in the art will not only understand the present invention and its attendant advantages, but will also find apparent various changes and modifications to the methods and structures disclosed. It is sought, therefore, to cover all such changes and modifications as fall within the spirit and scope of the invention, as defined by the appended claims, and equivalents thereof.

## Claims

1. Method, comprising:
transmitting a data-modulated high-frequency data signal fC in a given band range; 
transmitting an additional high-frequency data signal fS together with the high-frequency data signal fC in a band range different from the given band range; 
amplifying the high-frequency data signals fC and fs; 
mixing the high-frequency data signals fC and fs to generate a data-modulated intermediate-frequency data signal fIF; and 
data modulating the intermediate frequency data signal fIF.

2. The method according to claim 1, wherein the data-modulated high-frequency data signal fC is also carrier-code modulated.

3. The method as claimed in claim 2, further comprising:
separating the high-frequency data signals fC and fS subsequent to said transmitting of the additional high-frequency data signal fS.

4. The method as claimed in claim 3, wherein the high-frequency data signals fC and fS are separated in a filter.

5. The method as claimed in claim 2, wherein the high-frequency data signals fC and fS are mutually differently amplified.

6. The method as claimed in claim 2, further comprising:
decoding the high-frequency data signal fC using the additional high-frequency data signal fS.

7. The method as claimed in claim 1, wherein said mixing additionally converts and correlates the frequencies of the high-frequency data signals fC and fS.

8. A circuit, comprising:
an antenna receiving both a high-frequency data signal fC and an additional high-frequency data signal fS; 
amplifiers amplifying, respectively, the high-frequency data signals fC and fS; and 
a mixer mixing the high-frequency data signals fC and fS, to generate a data-modulated intermediate-frequency data signal fIF.

9. The circuit as claimed in claim 8, further comprising:
a filter unit separating the high-frequency data signals fC and fS.

10. The circuit as claimed in claim 9, wherein the filter unit is a diplexer filter.

11. The circuit as claimed in claim 8, wherein the mixer is a frequency converter and correlator mixer.

12. An identification system, comprising:
at least one transmitter transmitting a high-frequency data signal fC and an additional high-frequency data signal fS; 
at least one antenna receiving both the high-frequency data signal fC and the additional high-frequency data signal fS; 
at least one amplifier amplifying both the high-frequency data signal fC and the additional high-frequency data signal fS 
a filter unit separating the high-frequency data signal fC and the additional high-frequency data signal fS, and 
a mixer mixing the amplified high-frequency data signal fC and the additional high-frequency data signal fS and outputting a data-modulated intermediate-frequency data signal fIF.

13. The system as claimed in claim 12, wherein the filter unit comprises a diplexer filter.

14. The system as claimed in claim 12, wherein the mixer comprises a frequency converter and correlator mixer.

15. A system, comprising:
a read/write device; 
at least one data memory attached to an object and storing data regarding the object; 
at least one transmitter transmitting a high-frequency data signal fC and an additional high-frequency data signal fS; 
at least one antenna receiving both the high-frequency data signal fC and the additional high-frequency data signal fS; 
at least one amplifier amplifying both the high-frequency data signal fC and the additional high-frequency data signal fS; and 
a mixer mixing the amplified high-frequency data signal fC and the additional high-frequency data signal fS and outputting a data-modulated intermediate-frequency data signal fIF.

16. The system as claimed in claim 15, wherein the data includes at least one of status and process data of the object.

17. The system as claimed in claim 15, wherein the system is at least one of a shipping system, a transport system and a production system.

18. The system as claimed in claim 15, wherein the transmitter is associated with the data memory and the high-frequency data signal fC comprises the stored data regarding the object.