Apparatus and method for data transmission

Abstract

The present invention relates to a device for data transmission comprising a transmitter (10) for generating a frequency-modulated output signal (S5). The transmitter (10) has a phase-locked loop (30) for adjusting the output frequency of the output signal (S5) to a carrier frequency and a coupling circuit (20) for coupling a data stream (S1) to the phase-locked loop (30), wherein the output signal (S5) frequency-modulated by the coupled data stream (S1) has a time-variable output frequency, and wherein the coupling circuit (20) includes a compensation unit (22) that couples a compensation signal (S2) to the phase-locked loop (30), the compensation signal at least approximately adjusting the output frequency performed by the phase-locked loop (30) to the carrier frequency. The invention also relates to a method for data transmission using the device according to the invention.

Description

Technical Field

[0001] This invention relates to an apparatus for data transmission, comprising a transmitter for generating a frequency-modulated / frequency-modulated output signal. The invention also relates to a method for data transmission using the apparatus according to the invention. Background Technology

[0002] Frequency modulation is known in the prior art for transmitting data. This invention relates to a modulation method in which the carrier frequency is changed by the signal to be transmitted. Frequency modulation, compared to other modulation methods—such as amplitude modulation—enables a higher dynamic range for information signals. Furthermore, frequency modulation is less susceptible to interference.

[0003] A modulator for generating an output signal is known from the literature “A 10Mb / s hybrid Two Points Modulation with Front Check Select and Dual-Path DCO Modulation”. The modulator has a phase-locked loop (PLL), also known as a phase-locked loop (PLL), which in turn has a voltage-controlled oscillator (VCO).

[0004] The paper "Low-Power Transmitter for Phase Shift Keying Modulation Schemes" (2006 IEEE) discloses a modulation system for generating an output signal. This modulation system also features a phase-locked loop with a voltage-controlled oscillator.

[0005] A phase-locked loop with a tracking oscillator is known from document EP 1 318 598 A1. The output signal of the tracking oscillator is compared with a reference signal. A compensation signal is fed to the loop filter by a compensation unit, thereby compensating for signal offset.

[0006] A frequency generator with a voltage-controlled oscillator and a phase-locked loop is known from document EP 0 961 412 A1.

[0007] A method for frequency synthesis is known from US 5,920,556. In this method, a compensated error signal is generated and fed to a voltage-controlled oscillator.

[0008] To obtain a modulated output signal (which can be used for data transmission) at the output of the voltage-controlled oscillator (VCO) in the phase-locked loop (PLL), a control signal is applied to the input of the VCO. This control signal includes a DC component, which is superimposed with an offset. The offset depends on the bit pattern of the data stream to be transmitted. If the offset is maintained by the bit pattern, resulting in an output signal with a changed, particularly increased, output frequency compared to the carrier frequency, the PLL will adjust back to the original carrier frequency over time. In this case, proper demodulation of the output signal cannot be achieved for the output signal receiver acting as a communication partner. Summary of the Invention

[0009] Therefore, the object of the present invention is to improve the apparatus and method for data transmission by means of frequency modulation. In particular, it should be possible to achieve data transmission with relatively high bandwidth, wherein the desired deviation between the output frequency of the output signal and the carrier frequency is maintained during data transmission.

[0010] This objective is achieved by a device for data transmission having the features described in claim 1. Advantageous designs and improvements are the subject of the dependent claims. This objective is also achieved by a method for data transmission having the features described in claim 7. Advantageous designs and improvements are the subject of the dependent claims.

[0011] Such a device for data transmission includes a transmitter for generating a frequency-modulated output signal. The frequency-modulated output signal is, in particular, a time series having signal segments, each having at least an approximately constant signal frequency. Here, at least one signal frequency differs from the carrier frequency.

[0012] According to the invention, the transmitter has a phase-locked loop (PLL) for adjusting the output frequency of the output signal to the carrier frequency. Similarly, the transmitter has a coupling circuit for coupling a data stream into the PLL. Here, the output signal, frequency-modulated using the coupled data stream, has a time-variable output frequency. The coupling circuit includes a compensation unit that couples a compensation signal into the PLL. Here, the compensation signal at least approximately compensates for the adjustment of the output frequency to the carrier frequency implemented by the PLL.

[0013] The output frequency of the output signal generated by the transmitter can be adjusted to multiple signal frequencies according to the coupled data stream, wherein at least one signal frequency differs from the carrier frequency. This modulation method with exactly two signal frequencies is also known as "Frequency Shift Keying" (FSK). A modulation method with more than two signal frequencies is also known as "Multiple Frequency Shift Keying" (MFSK). By compensating for the coupling of the signal, it is advantageously prevented that the output frequency, set to the signal frequency, drifts towards the carrier frequency. Therefore, the desired deviation between the output frequency and the carrier frequency is maintained during data transmission.

[0014] According to an advantageous design of the invention, the coupling circuit of the transmitter has an addition point for adding the data stream to be coupled in and the compensation signal to form a correction signal. The coupling circuit here couples the correction signal into the phase-locked loop. Therefore, only the signal, i.e., the correction signal, needs to be coupled into the phase-locked loop. Such an addition point can be implemented relatively simply in terms of circuit technology.

[0015] According to a preferred embodiment of the invention, the phase-locked loop (PLL) includes a voltage-controlled oscillator for generating an output signal, a regulator for generating an adjustment signal, and a summing point for adding the adjustment signal and a correction signal to form a control signal. Here, the control signal is applied to the oscillator. The output frequency of the output signal is at least approximately proportional to the voltage of the control signal. The correction signal is coupled into the PLL, particularly by a coupling circuit.

[0016] The phase-locked loop (PLL) of the transmitter is constructed, for example, as a radar transmitter for performing radar measurements. Therefore, existing radar transmitters can be used to transmit data via frequency modulation. Thus, no additional separate circuitry is required to generate the frequency-modulated output signal. The output frequency can be changed relatively quickly from one signal frequency to another. The adjustment of the output towards the carrier frequency implemented in the PLL is relatively slow, especially when the PLL regulator has PT1 or PT2 characteristics. This relatively slow adjustment in the PLL is at least approximately compensated for by a compensation signal generated by the compensation unit.

[0017] According to an advantageous improvement of the invention, the compensation unit has a compensation input terminal to which an adjustment signal is applied. Here, the adjustment signal is generated, in particular, by a regulator of a phase-locked loop. Furthermore, the compensation unit advantageously has a compensation output terminal for generating the compensation signal.

[0018] According to another advantageous improvement of the invention, the coupling circuit has a switching unit by means of which the coupling circuit can be switched between a data transmission mode and a radar mode. In the data transmission mode, the data stream and compensation signal are coupled into the phase-locked loop. In the radar mode, no coupling of the data stream and compensation signal into the phase-locked loop occurs. When the phase-locked loop of the transmitter is a radar transmitter, the transmitter can, for example, be used alternately for data transmission and for performing radar measurements.

[0019] According to the method of data transmission by means of the device for data transmission according to the invention, a frequency-modulated output signal is generated by a transmitter. A coupling circuit couples the data stream to a phase-locked loop (PLL), such that the frequency-modulated output signal using the coupled data has a time-variable output frequency. A compensation signal is coupled from a compensation unit to the PLL, through which the adjustment performed by the PLL to tune the output frequency to the carrier frequency is at least approximately compensated.

[0020] The output frequency of the output signal generated by the transmitter is set to multiple signal frequencies based on the coupled data stream, at least one of which differs from the carrier frequency. By compensating for the coupling of the signal, the output frequency set to the signal frequency is advantageously prevented from drifting towards the carrier frequency. Therefore, the desired deviation between the output frequency and the carrier frequency is maintained during data transmission.

[0021] According to an advantageous design of the invention, at the summation point of the coupling circuit, the data stream and the compensation signal are summed into a correction signal. Here, the correction signal is coupled into the phase-locked loop by the coupling circuit. Therefore, only one signal, namely the correction signal, is coupled into the phase-locked loop. This summation of signals at the summation point can be implemented relatively simply in terms of circuit technology.

[0022] According to a preferred embodiment of the invention, the output signal is generated by a voltage-controlled oscillator (VCO) of the phase-locked loop (PLL). Furthermore, a regulating signal is generated by a regulator of the PLL. At the summation point of the PLL, the regulating signal and the correction signal are added together to form a control signal. The control signal is applied to the oscillator. Here, the output frequency of the output signal is at least approximately proportional to the voltage of the control signal. The correction signal is here, in particular, coupled into the PLL by a coupling circuit.

[0023] The phase-locked loop (PLL) of the transmitter is constructed, for example, as a radar transmitter used for performing radar measurements. Therefore, existing radar transmitters are used for data transmission via frequency modulation. Thus, no additional separate circuitry is needed to generate the frequency-modulated output signal. The output frequency can be changed relatively quickly from one signal frequency to another. The adjustment of the output frequency toward the carrier frequency implemented in the PLL is relatively slow, especially when the PLL regulator has PT1 or PT2 characteristics. This relatively slow adjustment in the PLL is at least approximately compensated for by a compensation signal generated by a compensation unit.

[0024] According to an advantageous improvement of the invention, an adjustment signal is applied to the compensation input terminal of the compensation unit. Here, the adjustment signal is generated, in particular, by the regulator of the phase-locked loop. Furthermore, a compensation signal is generated from the compensation output terminal of the compensation unit.

[0025] According to another advantageous improvement of the invention, the coupling circuit is switched sequentially between a data transmission mode and a radar mode by means of a switching unit. In the data transmission mode, the data stream and compensation signal are coupled into the phase-locked loop. In the radar mode, no coupling of the data stream and compensation signal into the phase-locked loop occurs. When the phase-locked loop of the transmitter is a radar transmitter, the transmitter is used, for example, alternately for data transmission and performing radar measurements.

[0026] Further advantages are provided by the dependent claims. The invention is not limited to the combination of features of the claims. For those skilled in the art, particularly for the purposes presented and / or by comparison with the prior art, other reasonable combinations of claims and / or individual claim features and / or specification features and / or drawing features are apparent. Attached Figure Description

[0027] The invention will now be explained in detail with reference to the accompanying drawings. The invention is not limited to the embodiments shown in the drawings. The drawings are merely schematic illustrations of the subject matter of the invention. The drawings show:

[0028] Figure 1 : A schematic diagram of the transmitter,

[0029] Figure 2 The time-varying curve of the data stream.

[0030] Figure 3 : The time variation curve of the compensation signal

[0031] Figure 4 Correct the time-varying curve of the signal.

[0032] Figure 5 Adjust the time-varying curve of the signal.

[0033] Figure 6 : The time-varying curve of the control signal

[0034] Figure 7 The time-varying curve of the control signal without compensation.

[0035] Figure 8 The time-varying curve of the output frequency of the output signal.

[0036] Figure 9 : The time-varying curve of the output frequency of the output signal without compensation. Detailed Implementation

[0037] Figure 1 A schematic diagram of a transmitter 10 for data transmission is shown. The transmitter 10 generates a frequency-modulated output signal S5. The transmitter 10 includes a phase-locked loop 30 and a coupling circuit 20. The phase-locked loop 30 is a radar transmitter and is used to perform radar measurements.

[0038] The phase-locked loop 30 includes a voltage-controlled oscillator 32, which generates an output signal S5 with a variable output frequency. The phase-locked loop 30 also includes an amplifier 38, which amplifies the output signal S5 into an amplified output signal S7 with the same variable output frequency.

[0039] Phase-locked loop 30 includes a frequency divider 40 to which the output signal S5 generated by voltage-controlled oscillator 32 is fed. Frequency divider 40 has a division ratio of the current integer. Frequency divider 40 generates an input signal S8 whose input frequency is equivalent to the output frequency of output signal S5 divided by the division ratio.

[0040] The phase-locked loop 30 includes a detector 42 to which a reference signal S10 with a reference frequency is supplied. An input signal S8 with an input frequency, generated by a frequency divider 40, is also provided to the detector 42. The detector 42 compares the reference frequency of the reference signal S10 with the input frequency of the input signal S8. The detector 42 outputs an error signal S9. The detector 42 specifically includes a charge pump for outputting the error signal S9. The error signal S9 is correlated with the reference frequency of the reference signal S10 and with the difference between the reference signal S10 and the input signal S8.

[0041] The phase-locked loop 30 includes a regulator 34 to which the error signal S9 is fed. The regulator 34 generates an adjustment signal S4. The regulator 34 has either PT1 or PT2 characteristics. The adjustment signal S4 is an analog signal, the voltage of which is a measure of the adjustable output frequency of the output signal S5 generated by the oscillator 32.

[0042] The phase-locked loop 30 includes a summing point 36. At the summing point 36, the adjustment signal S4 and the correction signal S3 are summed into a control signal S6. The control signal S6 is applied to the oscillator 32. The output frequency of the output signal S5 generated by the oscillator 32 is proportional to the voltage of the control signal S6.

[0043] The coupling circuit 20 has a switching unit 28. The switching unit 28 can be used to switch the coupling circuit 20 to a data transmission mode and to a radar mode. The switching unit 28 generates, for example, a binary switching signal S11. The mode switched by the coupling circuit 20 is encoded in the switching signal S11.

[0044] The coupling circuit 20 includes a compensation unit 22 to which a switching signal S11 is supplied. The compensation unit 22 has a compensation input terminal 25, which includes an analog-to-digital converter. An adjustment signal S4 is supplied to the compensation input terminal 25. The compensation unit 22 also has a compensation output terminal 26, which includes a digital-to-analog converter. When the coupling circuit 20 is switched to data transmission mode, a compensation signal S2 is generated by the compensation output terminal 26.

[0045] The input data stream S0 is fed to the switching unit 28. When the coupling circuit 20 is switched to data transmission mode, the switching unit 28 generates a data stream S1 corresponding to the input data stream S0. If possible, the switching unit 28 performs level adjustment or modulation on the input data stream S0. The data stream S1 is currently a binary signal and has a state "0" or a state "1".

[0046] The coupling circuit 20 has an addition point 24. At the addition point 24, the data stream S1 and the compensation signal S2 are added together to form a correction signal S3. The correction signal S3 is coupled into the phase-locked loop 30. In particular, the correction signal S3 is fed to the addition point 36.

[0047] Figure 2 An exemplary time-varying curve of data stream S1, which is a binary signal in this case, is shown. Time t is plotted on the horizontal axis, and the voltage V of data stream S1 is plotted on the vertical axis. The voltage V of data stream S1 initially has a voltage value corresponding to state "0". At time t0, data stream S1 changes its state, and its voltage V now jumps to the voltage value corresponding to state "1". The voltage value corresponding to state "0" is now greater than the voltage value corresponding to state "1".

[0048] Figure 3 An exemplary time-varying curve of the compensation signal S2 is shown. Time t is plotted on the horizontal axis, and the voltage V of the compensation signal S2 is plotted on the vertical axis. Initially, the voltage value of the compensation signal S2 is constant. From time t0, the voltage value of the compensation signal S2 continuously increases.

[0049] Figure 4 An exemplary time-varying curve of the correction signal S3 is shown. Time t is plotted on the horizontal axis, and the voltage V of the correction signal S3 is plotted on the vertical axis. Initially, the voltage value of the correction signal S3 is constant. At time t0, the voltage V of the correction signal S3 jumps to a higher voltage value. From time point t0 onwards, the voltage value of the correction signal S3 continuously increases. The voltage value of the correction signal S3 is equivalent to the sum of the voltage values ​​of the data stream S1 and the compensation signal S2.

[0050] Figure 5 An exemplary time-varying curve of the regulating signal S4 is shown. Time t is plotted on the horizontal axis, and the voltage V of the regulating signal S4 is plotted on the vertical axis. Initially, the voltage value of the regulating signal S4 is constant. From time t0, the voltage value of the regulating signal S4 continuously decreases. The compensation signal S2 is complementary to the regulating signal S4, especially from time t0. Therefore, the decrease in the regulating signal S4 is compensated by the increase in the compensation signal S2.

[0051] Figure 6 An exemplary time-varying curve of control signal S6 is shown. Time t is plotted on the horizontal axis, and the voltage V of control signal S6 is plotted on the vertical axis. Initially, the voltage value of control signal S6 is constant. At time t0, the voltage V of control signal S6 jumps to a higher voltage value. The voltage value of control signal S6 is equivalent to the sum of the voltage values ​​of correction signal S3 and adjustment signal S4.

[0052] For comparison, Figure 7 The time-varying curve of control signal S6 without compensation, i.e., without the generation of compensation signal S2, is shown. Time t is plotted on the horizontal axis, and the voltage V of control signal S6 is plotted on the vertical axis. Initially, the voltage value of control signal S6 is constant. At time t0, the voltage V of control signal S6 jumps to a higher voltage value. From time t0 onwards, the voltage value of control signal S6 continuously decreases. In this case, the voltage value of control signal S6 is equivalent to the sum of the voltage values ​​of data stream S1 and adjustment signal S4.

[0053] Figure 8 An exemplary time-varying curve of the output frequency of output signal S5 is shown. Time t is plotted on the horizontal axis, and frequency f is plotted on the vertical axis. The output frequency of output signal S5 initially has a first signal frequency. At time t0, the output frequency of output signal S5 jumps to a second signal frequency. The second signal frequency is here higher than the first signal frequency.

[0054] Here, the output frequency of output signal S5 is related to the voltage value of data stream S1. When the voltage value of data stream S1 corresponds to state "0", the output frequency of output signal S5 has a first signal frequency. When the voltage value of data stream S1 corresponds to state "1", the output frequency of output signal S5 has a second signal frequency.

[0055] For comparison, Figure 9 The graph shows the time-varying frequency of the output signal S5 without compensation, i.e., without the generation of compensation signal S2. Time t is plotted on the horizontal axis, and frequency f is plotted on the vertical axis. The output frequency of the output signal S5 initially has a first signal frequency. At time t0, the output frequency of the output signal S5 jumps to a second signal frequency. From time t0 onwards, the output frequency of the output signal S5 continuously decreases.

[0056] The first signal frequency currently corresponds to the carrier frequency, while the second signal frequency differs from the carrier frequency. Starting from time t0, the phase-locked loop 30 adjusts the output frequency of the output signal S5 to the carrier frequency. The change curve of the output frequency of the output signal S5 from time t0 is particularly determined by the characteristics of the regulator 34. Currently, the regulator 34 exhibits either PT1 or PT2 characteristics. Therefore, the output frequency of the output signal S5 asymptotically approaches the carrier frequency.

[0057] List of reference numerals in the attached diagram:

[0058] 10 Transmitters

[0059] 20 Coupled Circuit

[0060] 22 Compensation Units

[0061] 24 Addition Points

[0062] 25 Compensation Input Terminal

[0063] 26 Compensation Output Terminal

[0064] 28 Switching Units

[0065] 30 Phase-locked loop

[0066] 32 Oscillators

[0067] 34 Regulator

[0068] 36 sum points

[0069] 38 Amplifier

[0070] 40 frequency divider

[0071] 42 detectors

[0072] S0 Input Data Stream

[0073] S1 data stream

[0074] S2 Compensation Signal

[0075] S3 correction signal

[0076] S4 Adjustment Signal

[0077] S5 output signal

[0078] S6 control signal

[0079] S7 Amplified Output Signal

[0080] S8 Input Signal

[0081] S9 error signal

[0082] S10 Reference Signal

[0083] S11 switch signal

[0084] V voltage

[0085] t time

[0086] time t0

[0087] f frequency

Claims

1. A device for data transmission, comprising: A transmitter (10) for generating a frequency-modulated output signal (S5). Its features are, The transmitter (10) has a phase-locked loop (30) for adjusting the output frequency of the output signal (S5) to the carrier frequency. The transmitter has a coupling circuit (20) for coupling the data stream (S1) into the phase-locked loop (30). The output signal (S5) that is frequency modulated using the coupled data stream (S1) has a time-varying output frequency. The coupling circuit (20) includes a compensation unit (22). The compensation unit couples a compensation signal (S2) into the phase-locked loop (30), which at least approximately compensates for the adjustment performed by the phase-locked loop (30) to tune the output frequency to the carrier frequency. The phase-locked loop (30) of the transmitter (10) is configured as a radar transmitter for performing radar measurements. The coupling circuit (20) has a switching unit (28), which allows the coupling circuit (20) to be switched between the data transmission module and the radar mode. In the data transmission mode, the data stream (S1) and the compensation signal (S2) are coupled into the phase-locked loop (30). In radar mode, no data stream (S1) and compensation signal (S2) are coupled into the phase-locked loop (30). The compensation unit (22) has a compensation input terminal (25) and a compensation output terminal (26). An adjustment signal (S4) is applied to the compensation input terminal, and the compensation output terminal is used to generate a compensation signal (S2).

2. The device according to claim 1, characterized in that, The coupling circuit (20) has an addition point (24) for adding the data stream (S1) to the compensation signal (S2) to form a correction signal (S3), and The coupling circuit (20) couples the correction signal (S3) into the phase-locked loop (30).

3. The device according to at least one of the preceding claims, Its features are, The phase-locked loop (30) includes: a voltage-controlled oscillator (32) for generating an output signal (S5), a regulator (34) for generating an adjustment signal (S4), and a summing point (36) for summing the adjustment signal (S4) and the correction signal (S3) into a control signal (S6). Among them, the control signal (S6) is applied to the oscillator (32), Furthermore, the output frequency of the output signal (S5) is at least approximately proportional to the voltage of the control signal (S6).

4. A method for transmitting data using a device according to at least one of claims 1-3. Its features are, The transmitter (10) generates a frequency-modulated output signal (S5). The data stream (S1) is coupled into the phase-locked loop (30) by the coupling circuit (20), so that the output signal (S5) modulated by the coupled data stream (S1) has a time-varying output frequency. The compensation unit (22) couples the compensation signal (S2) into the phase-locked loop (30), and the compensation signal (S2) at least approximately compensates the adjustment performed by the phase-locked loop (30) to adjust the output frequency to the carrier frequency.

5. The method according to claim 4, characterized in that, At the addition point (24) of the coupling circuit (20), the data stream (S1) and the compensation signal (S2) are added together to form the correction signal (S3). The coupling circuit (20) couples the correction signal (S3) into the phase-locked loop (30).

6. The method according to at least one of claims 4 to 5, Its features are, The voltage-controlled oscillator (32) of the phase-locked loop (30) generates the output signal (S5). The regulator (34) of the phase-locked loop (30) generates the regulation signal (S4). At the summing point (36) of the phase-locked loop (30), the adjustment signal (S4) and the correction signal (S3) are summed to form the control signal (S6). Apply the control signal (S6) to the oscillator (32). The output frequency of the output signal (S5) is at least approximately proportional to the voltage of the control signal (S6).

7. The method according to at least one of claims 4 to 6, Its features are, An adjustment signal (S4) is applied to the compensation input terminal (25) of the compensation unit (22), and a compensation signal (S2) is generated by the compensation output terminal (26) of the compensation unit (22).

8. The method according to at least one of claims 4 to 7, Its features are, The coupling circuit (20) switches sequentially between data transmission mode and radar mode by means of the switching unit (28). In the data transmission mode, the data stream (S1) and the compensation signal (S2) are coupled into the phase-locked loop (30). In radar mode, no data stream (S1) and compensation signal (S2) are coupled into the phase-locked loop (30).

Images