Circuit arrangement and method for generating a radio-frequency, analogue transmission signal using reduced interference signals

Abstract

A circuit arrangement for generating a high-frequency, analog transmission signal, in particular a high-frequency, analog single-carrier transmission signal. The circuit arrangement has a synthesis apparatus for generating the high-frequency, analog transmission signal on the basis of a discrete frequency spectrum of a digital modulated, baseband signal. A transmission device for transmitting a high-frequency, analog transmission signal. The transmission device having an antenna for transmitting the transmission signal, and a synthesis apparatus for generating the high-frequency, analog transmission signal, on a basis of a discrete frequency spectrum of a digital, modulated baseband signal. A method for transmitting a high-frequency, analog transmission signal, which is a high-frequency, analog single-carrier transmission signal. The method includes providing a discrete frequency spectrum of a modulated, digital baseband signal; generating the high-frequency, analog transmission signal on the basis of the discrete frequency spectrum; and transmitting the high-frequency, analog transmission signal by means of an antenna.

Claims

1. A transmission device for transmitting a high-frequency, analog single carrier transmission signal, the transmission device comprising: an antenna for transmitting the high-frequency, analog single carrier transmission signal, and a synthesis apparatus for generating the high-frequency, analog single carrier transmission signal on a basis of a discrete frequency spectrum of a digital, modulated baseband signal, wherein the synthesis apparatus is an apparatus for carrying out a continuous, inverse Fourier transformation.

2. The transmission device as claimed in claim 1, wherein the discrete frequency spectrum has a plurality of Fourier coefficients, which are each assigned to a first frequency in a baseband range, and wherein in each case, two first frequencies have a prescribed frequency spacing.

3. The transmission device as claimed in claim 2, wherein the synthesis apparatus has a plurality of signal sources, by means of which periodic signals can be generated at two frequencies in a frequency range that is raised compared to a baseband range, wherein in each case, two second frequencies have the prescribed frequency spacing.

4. The transmission device as claimed in claim 3, wherein the synthesis apparatus has a plurality of weighting devices, by means of which a weighting of the plurality of signal sources can be set depending on the discrete frequency spectrum so that a plurality of signal components of the high-frequency, analog single carrier transmission signal can be generated, and wherein in each case, two signal components have the prescribed frequency spacing.

5. The transmission device as claimed in claim 3, wherein the raised frequency range is an intermediate frequency range located between the baseband range and the range of transmission frequencies, and wherein the synthesis apparatus has a mixer stage, in which the periodic signals at two frequencies can be mixed using an analog oscillator signal generated depending on the discrete frequency spectrum so that a plurality of signal components of the high-frequency, analog single carrier transmission signal can be generated.

6. The transmission device as claimed in claim 3, wherein the signal sources have an apparatus for direct digital synthesis of the periodic signal.

7. The transmission device as claimed in claim 1, wherein the transmission device has an analysis apparatus for calculating the discrete frequency spectrum on a basis of the digital, modulated baseband signal, the analysis apparatus is configured as an apparatus for carrying out a discrete Fourier transformation of the digital, modulated baseband signal.

8. The transmission device as claimed in claim 1, wherein the transmission device has a modulation apparatus for generating the discrete frequency spectrum of the digital, modulated baseband signal on a basis of a digital, unmodulated payload stream.

9. A circuit arrangement for generating a high-frequency, analog single carrier transmission signal, wherein the circuit arrangement has a synthesis apparatus for generating the high-frequency, analog single carrier transmission signal on a basis of a discrete frequency spectrum of a digital baseband signal, and wherein the synthesis apparatus is an apparatus for carrying out a continuous, inverse Fourier transformation.

10. Use of the circuit arrangement as claimed in claim 9 for generating the high-frequency, analog single carrier transmission signal in a transmission frequency band above 57 GHz.

11. Use of the circuit arrangement as claimed in claim 9 for generating the high-frequency, analog single carrier transmission signal in a transmission frequency range from 57 GHz to 66 GHz.

12. A method for transmitting a high-frequency, analog single transmission signal that is a high-frequency, analog single-carrier transmission signal, the method comprising: providing a discrete frequency spectrum of a digital baseband signal; generating the high-frequency, analog single carrier transmission signal on a basis of the discrete frequency spectrum by means of an apparatus for carrying out a continuous, inverse Fourier transformation; and transmitting the high-frequency, analog single carrier transmission signal by means of an antenna.

13. The method as claimed in claim 12, wherein the method comprises: calculating the discrete frequency spectrum of the digital baseband signal on the basis of the digital baseband signal by means of a discrete Fourier transformation to provide the high-frequency, analog single carrier transmission signal.

14. The method as claimed in claim 13, wherein the calculating step is preceded by windowing of the digital baseband signal.

15. The method as claimed in claim 14, wherein a plurality of temporally overlapping sections of the baseband signal are used to calculate the discrete frequency spectrum.

16. The method as claimed in claim 12, wherein the method comprises: generating the discrete frequency spectrum of the digital baseband signal proceeding from a digital payload stream to provide the high-frequency, analog single carrier transmission signal.

17. The method as claimed in claim 12, wherein the discrete frequency spectrum has a plurality of Fourier coefficients, which are each assigned to a first frequency in a baseband range, wherein in each case two first frequencies have a prescribed frequency spacing, wherein periodic signals are generated at two frequencies in a frequency range that is elevated compared to the baseband range, wherein in each case two second frequencies have the prescribed frequency spacing, wherein signal components of the high-frequency, analog single carrier transmission signal are generated on the basis of the periodic signals and the Fourier coefficients, and wherein in each case two signal components have the prescribed frequency spacing.

18. The method as claimed in claim 17, wherein the raised frequency range is a transmission frequency range, and the generated signal components are summed to generate the high-frequency, analog single carrier transmission signal.

19. The method as claimed in claim 17, wherein the frequency range that is elevated is an intermediate frequency range located between the frequency range of the baseband signal the frequency range of the transmission signal, wherein a common oscillator signal is additionally used to generate the signal components of the high-frequency, analog single carrier transmission signal, and wherein the frequency of the common oscillator signal is located in a range below the frequency range of the transmission signal.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows a transmission device according to the prior art.

(2) FIG. 2 shows a transmission device for transmitting a high-frequency, analog transmission signal according to a first exemplary embodiment of the invention.

(3) FIG. 3 shows a transmission device for transmitting a high-frequency, analog transmission signal according to a second exemplary embodiment of the invention.

(4) FIG. 4 shows a block diagram of a first exemplary embodiment of a synthesis apparatus for generating a high-frequency, analog transmission signal depending on a digital baseband signal.

(5) FIG. 5 shows a spectral diagram for illustrating the frequency shift in the frequency range.

(6) FIG. 6 shows a block diagram of a second exemplary embodiment of a synthesis apparatus for generating a high-frequency, analog transmission signal depending on a digital baseband signal.

(7) FIG. 7 shows a block diagram of a third exemplary embodiment of a transmission device for transmitting a high-frequency, analog transmission signal according to the invention.

(8) FIGS. 8a and 8b show a schematic illustration to explain the functioning of the transmission device according to FIG. 7.

(9) FIG. 9 shows a block diagram of a fourth exemplary embodiment of a transmission device for transmitting a high-frequency, analog transmission signal according to the invention.

(10) FIGS. 10a and 10b show a schematic illustration to explain the functioning of the transmission device according to FIG. 9.

DETAILED DESCRIPTION

(11) In the various figures, identical parts are always provided with the same reference signs and are therefore generally also each only mentioned once.

(12) FIG. 1 shows a transmission device 1 for transmitting a high-frequency, analog transmission signal 10 according to the prior art, which transmission device is configured as an RF transmitter, wherein the elements of the transmission device 1 that process signals in the baseband are characterized by the reference sign BB.

(13) The transmission device 1 has a modulation device 2, by means of which a digital baseband signal 3 is provided. The digital baseband signal 3 is oversampled in a sampling apparatus 4, that is to say the sampling is carried out at a sampling rate that is higher than the Nyquist frequency of the baseband signal 3. The oversampled baseband signal is fed to a digital low-pass filter 5 in order to smooth steep level changes of the signal. The oversampled and low-pass-filtered baseband signal is then subjected to digital-to-analog conversion and to frequency transformation to a carrier frequency in an RF-DAC 6. The RF-DAC 6 has a digital-to-analog converter 7 and a mixer 9 for this purpose. The carrier frequency is provided by means of an oscillator 8.

(14) The RF-DAC 7 generates a high-frequency, analog transmission signal 10, which is amplified by means of an amplifier 11. The amplified transmission signal is filtered into an analog filter 12 and then emitted by means of an antenna 13. The high-frequency, analog transmission signal 10 is a high-frequency, analog single-carrier transmission signal 10.

(15) The transmission device 1 shown in FIG. 1 has the disadvantage that the circuitry outlay for implementing the oversampling and digital filtering of the baseband signal is very high. The high switching frequency of the circuits for processing the baseband signal also produces glitches, which promote the emission of undesired interference signals. The RF-DAC also has to operate at a high clock frequency in order to be able to implement a correspondingly high sampling rate. This also promotes the production of glitches.

(16) FIG. 2 shows a transmission device 100 according to a first exemplary embodiment of the invention. Such elements of the transmission device 1 that process signals in the baseband are characterized by the reference sign BB.

(17) The transmission device 100 is configured as an RF transmitter and has a circuit arrangement 101 for generating a high-frequency, analog transmission signal 109 and an antenna 112, by means of which the transmission signal can be emitted. Part of the transmission device 100 is also a conventional modulator 102, by means of which a digital baseband signal 103 is provided, for example a complex, digital baseband signal, which has a real component (I component) and an imaginary component (Q component). The modulator 102 generates the digital, modulated baseband signal 103 from an unmodulated payload stream. The modulator 102 can be, for example, a QAM modulator.

(18) The circuit arrangement 101 comprises an analysis apparatus 104 for calculating a discrete frequency spectrum of the baseband signal 103 and a synthesis apparatus 105 for generating the high-frequency, analog transmission signal on the basis of the discrete frequency spectrum. A method in which a discrete frequency spectrum of the digital baseband signal 103 is calculated by means of the analysis apparatus 104 and a high-frequency, analog transmission signal 109, in particular a high-frequency, analog single-carrier transmission signal is generated on the basis of the calculated discrete frequency spectrum can thus be carried out by means of the circuit arrangement 101. It is not necessary to subject the digital baseband signal 103 to oversampling and/or filtering in order to reduce parasitic emissions. The circuit arrangement 101 can be operated at a reduced switching frequency, as a result of which the occurrence of glitches can be reduced and the emission of undesired interference signals can be decreased.

(19) In the circuit arrangement 101 according to the first exemplary embodiment, the analysis apparatus 104 is configured as an apparatus for carrying out a discrete Fourier transformation, in particular for carrying out a fast Fourier transformation (FFT). The analysis apparatus 104 samples in each case N symbols of the digital baseband signal 103 in the time domain and calculates a discrete frequency spectrum for these N symbols, which discrete frequency spectrum has N Fourier coefficients c.sub.0, c.sub.1, . . . , c.sub.N1 (N-point-FFT). The N Fourier coefficients represent a measure of the spectral power of the DC component of the baseband signal 103 and of N1 baseband frequencies of the baseband signal 103, wherein the N1 baseband frequencies each have a spacing of f=BW/N, wherein BW is the bandwidth of the digital baseband signal. The Fourier coefficients constitute a representation of the baseband signal 103 in the frequency domain.

(20) FIG. 3 shows a second exemplary embodiment of a transmission device 100 according to the invention. The transmission device 100 corresponds in large parts to the transmission device of the first exemplary embodiment. In contrast to the first exemplary embodiment, this transmission device 100 has a modulation device 106, by means of which a discrete frequency spectrum of the digital baseband 103 is generated directly from a digital, unmodulated payload stream. In the transmission device 100 according to the second exemplary embodiment, a separate analysis apparatus is therefore not required since the digital, modulated baseband signal 103 is provided directly in the frequency domain.

(21) In the transmission devices 100 described above, the circuit arrangement 101 can be configured as an integrated circuit arrangement. The transmission devices 100 also have an amplifying device 110 for amplifying the transmission signal 109 and an analog filter 111, which are arranged in the signal flow between the synthesis apparatus 105 and the antenna 112. The amplifying device 110 and/or the analog filter 111 and/or the modulator 102 and/or the modulation device 116 can be be configured as part of the circuit arrangement 101 in a modification of the exemplary embodiments illustrated in FIGS. 2 and 3. As an alternative, the amplifying device 110 and/or the analog filter 111 and/or the modulator 102 and/or the modulation device 116 can be provided as elements that are separate from the circuit arrangement 101.

(22) The configuration of the synthesis apparatus 105 will be dealt with in more detail below. These embodiments can be applied to all of the exemplary embodiments of the transmission device 100 that are explained above.

(23) The synthesis apparatus 105 of the circuit arrangement 101 is designed as an apparatus for carrying out a continuous, inverse Fourier transformation. The synthesis apparatus 105similarly to in an RF-DACconverts the digital baseband signal 104 to a continuous, analog transmission signal 109, in particular a single-carrier transmission signal, and shifts the frequency to a transmission frequency band, which is shifted from the baseband by a prescribed frequency constant f.sub.c. In contrast to the RF-DAC 6 shown in FIG. 1, the discrete frequency spectrum calculated by the analysis apparatus 104 is fed to the synthesis apparatus 105 in the form of the Fourier coefficients c.sub.0, c.sub.1, . . . c.sub.N1 instead of a digital baseband signal in the time domain. Frequencies in the transmission frequency band are assigned to said Fourier coefficients c.sub.0, c.sub.1, . . . c.sub.N1, which frequencies each have a spacing of f with respect to one another and are shifted with respect to the corresponding frequencies from the baseband range by the prescribed frequency constant f.sub.c, as is illustrated in FIG. 5 for clarification. In this respect, the synthesis apparatus can be referred to as an RF-FAC (Radio Frequency Fourier-to-Analog Converter), which transmits the baseband signal from the frequency domain back to the time domain and in the process carries out frequency transformation to the transmission frequency band.

(24) FIG. 4 shows a block circuit diagram of the synthesis apparatus 105. The synthesis apparatus 105 has a total of N signal sources 116 configured as current sources, which provide sinusoidal currents at the transmission frequencies f.sub.c, f.sub.c+f, f.sub.c+2f, . . . , f.sub.c+(N2)f, f.sub.c+(N1)f. The sinusoidal current of each signal source 116 is modulated by means of in each case a weighting device 117 designed as an amplifying device so that the ratio of the sinusoidal currents to one another can be set. The weighting in the weighting devices 117 is effected depending on the Fourier coefficients c.sub.0, c.sub.1, . . . c.sub.N1, wherein a Fourier coefficient c.sub.0, c.sub.1, . . . c.sub.N1 is assigned to each weighting device 117. The Fourier coefficient c.sub.0, c.sub.1, . . . c.sub.N1 of a baseband frequency is in this case assigned to a transmission frequency that results from addition of a prescribed frequency constant f.sub.c and the respective baseband frequency.

(25) As can further be seen from the illustration in FIG. 4, the weighting devices 117 are connected to a common output of the synthesis apparatus 105 at which the generated transmission signal 109 is available. The transmission signal 109 results here from summing of the weighted currents of the individual signal sources 116. A plurality of signal components of the high-frequency, analog transmission signal 109, in particular of the high-frequency, analog single-carrier transmission signal, are thus generated, wherein in each case two signal components have the prescribed frequency spacing f. The summation current obtained is a reconstruction of the baseband time signal, which reconstruction is shifted to the transmission frequency band, wherein the transitions between the individual symbols are sinusoidal. The bandwidth BW of the transmission signal 109 corresponds to the bandwidth BW of the baseband signal 103, cf. also FIG. 5.

(26) To transmit N symbols, the Fourier coefficients c.sub.0, c.sub.1, . . . c.sub.N1 are each used once so that the switching frequency of the synthesis apparatus 105, in particular of the weighting apparatuses 117, is comparatively low.

(27) FIG. 6 shows a block circuit diagram of a second exemplary embodiment of a synthesis apparatus 105, wherein the block circuit diagram comprises the elements that are required to generate precisely one signal component 109.1 of the high-frequency, analog transmission signal 109 from complex-valued Fourier coefficients having a real part c.sub.i,1 and an imaginary part c.sub.i,2. This means that the synthesis apparatus 105 comprises a total of N-times the design shown in FIG. 6. The signal components 109.1 are then summed to form the high-frequency, analog transmission signal 109.

(28) In said synthesis apparatus 105, periodic signals are generated in a raised frequency range, which is an intermediate frequency range located between the baseband range and the range of the transmission frequencies. In this respect, the baseband signal is first transformed to an intermediate frequency range and then to the transmission frequency range. First, the real part c.sub.i,1 and the imaginary part c.sub.i,2 of the complex-valued Fourier coefficients are multiplicatively mixed using in each case a first oscillator signal cos(f.sub.LO) and a second oscillator signal sin (f.sub.LO) that is phase-shifted with respect to the first oscillator signal by 90. The first oscillator signal cos(f.sub.LO) and the second oscillator signal sin(f.sub.LO) constitute two common oscillator signals, which are used to generate all of the signal components 109.1 of the high-frequency, analog transmission signal 109. The frequency of the first oscillator signal cos(f.sub.LO) and of the second oscillator signal sin(f.sub.LO) is identical and is located below the transmission frequency of the transmission signal 109. In this respect, the following intermediate-frequency signals are formed: a first intermediate-frequency signal is formed from the first oscillator signal cos(f.sub.LO) and the real part c.sub.i,1 of the Fourier coefficient. A second intermediate-frequency signal is generated from the second oscillator signal sin(f.sub.LO) and the real part c.sub.i,1 of the Fourier coefficient. A third intermediate-frequency signal is also formed from the first oscillator signal cos(f.sub.LO) and the imaginary part c.sub.i,2 of the complex-valued Fourier coefficients. A fourth intermediate-frequency signal is generated from the second oscillator signal sin(f.sub.LO) and the imaginary part c.sub.i,2.

(29) The synthesis apparatus 105 further comprises a plurality of signal sources 116 for generating the periodic signals, which are generated in a frequency range that is raised in comparison to the baseband range. The signal sources 116 each have an apparatus for direct digital synthesis (DDS) of the periodic signals, which is subsequently referred to as DDS apparatus. Each DDS apparatus generates a periodic DDS signal at a prescribed frequency proceeding from a digital counter. A first analog, periodic signal cos(f.sub.IF+iF) and a second analog, second periodic signal sin(f.sub.IF+iF) that is phase-offset compared to the first periodic signal cos(f.sub.IF+iF) by 90 is derived from said DDS signal, which signals both have half the frequency of the DDS signal. Two of the periodic signals cos(f.sub.IF+iF), sin(f.sub.IF+iF) generated in the signal sources 116 each have the prescribed frequency spacing N. The periodic signals cos(f.sub.IF+iF), sin(f.sub.IF+iF) are mixed in a mixer stage comprising a plurality of mixers 118 each having one of the intermediate-frequency signals. The first intermediate-frequency signal and the fourth intermediate-frequency signal are each mixed with the first periodic signal cos(f.sub.IF+iF). Furthermore, the second intermediate-frequency signal and the third intermediate-frequency signal are mixed with the second analog, periodic signal sin(f.sub.IF+iF). The mixed products obtained in this way are linked in such a way that the lower sideband in the transmission signal component 109.1 is suppressed so that a HF signal HF.sub.OSB is obtained, which contains exclusively the upper sideband. The linking satisfies the equation
HF=ZF1.Math.cos(f.sub.IF+iF)ZF2.Math.sin(f.sub.IF+iF)+ZF3.Math.sin(f.sub.IF+iF)ZF4.Math.cos(f.sub.IF+iF),
wherein HF is the HF signal, ZF1 is the first intermediate-frequency signal, ZF2 is the second intermediate-frequency signal, ZF3 is the third intermediate-frequency signal, ZF4 is the fourth intermediate-frequency signal, cos(f.sub.IF+iF) is the first analog, periodic signal and sin(f.sub.IF+iF) is the second analog, periodic signal. In this way, it can be ensured that the generated transmission signal 109 has only frequency components either in the upper or in the lower sideband, since either those signals that generate frequency components in the lower sideband or those signals that generate frequency components in the upper sideband cancel each other out. It is therefore possible to omit filtering of the transmission signal in order to suppress the upper or lower sideband.

(30) In the synthesis apparatus according to FIG. 6, the Fourier coefficients are first multiplicatively mixed with the first oscillator signal cos(f.sub.LO) and the second oscillator signal sin (f.sub.LO) that is phase-shifted with respect to the first oscillator signal by 90 before mixing with the first periodic signal cos(f.sub.IF+iF) generated by means of the DDS apparatus and the second periodic signal cos(f.sub.IF+iF) takes place. In a modification of the synthesis apparatus 105 shown in FIG. 6, this principle is reversed so that first the mixing with the first periodic signal cos(f.sub.IF+iF) generated by means of the DDS apparatus and the second periodic signal cos(f.sub.IF+iF) takes place and in a second step the mixing with the common first oscillator signal cos(f.sub.LO) and the common second oscillator signal sin (f.sub.LO)

(31) FIG. 7 shows a third exemplary embodiment of a transmission device 100 for transmitting a high-frequency, analog transmission signal 109, which is formed as a single-carrier transmission signal. In this respect, said transmission device is a transmission device 100 in the form of an RF transmitter for a single-carrier transmission signal. The transmission device 100 has a modulator 102, a circuit arrangement 101 for generating the high-frequency, analog transmission signal 109 and an antenna 112, by means of which the transmission signal 109 is emitted. In the circuit arrangement 101, particular measures have been taken to reduce undesired effects on the quality of the transmission signal 109. The transmission device 100 according to the third exemplary embodiment uses an additional method step, which precedes the calculation of the discrete frequency spectrum and is also referred to as windowing.

(32) The analysis apparatus 104 of the circuit arrangement 101 is configured as an apparatus for discrete Fourier transformation and has a plurality of, in particular two, transformation units 157, 158. Respective sections of the baseband signal 103 are fed to each of said transformation units 157, 158, which sections correspond to a prescribed window width of N symbols. To this end, the modulated, digital baseband signal 103 is delayed in a delay device 150, in particular by a period that corresponds to half of a window width N. The delay device 150 generates a delayed baseband signal 151. The non-delayed baseband signal 103 is fed to a first series-to-parallel converter 153 and the delayed baseband signal 151 is fed to a second series-to-parallel converter 152.

(33) The baseband signals that are paralleled by the series-to-parallel converters 152, 153 are each fed to a windowing unit 154, 155, in which the paralleled baseband signals are weighted using a prescribed window function, cf. FIG. 8a. The prescribed window function is designed in such a way that the amplitudes of the weighted signals at the edges of the respective window tend toward zero. This means that the window function at the edge of the window has a higher attenuation than in the center of the window. This can reduce the occurrence of discontinuities and/or high-frequency interference in the high-frequency analog transmission signal 109.

(34) The paralleled baseband signals weighted by the windowing units 154, 155 are fed to the analysis apparatus 104.

(35) The transformation units 157, 158 of the analysis apparatus 104 carry out a discrete Fourier transformation of the respective sections of the baseband signal in parallel. In a first transformation unit 158, the baseband signal paralleled in the first series-to-parallel converter 153 and weighted in a first windowing unit 155 is subjected to a discrete Fourier transformation. In a second transformation unit 157, the baseband signal delayed in the delay unit 150, paralleled in the second series-to-parallel converter 152 and weighted in the second windowing unit 154 is subjected to a discrete Fourier transformation. The transformation units 157, 158 each calculate a discrete partial frequency spectrum, which has N Fourier coefficients. The Fourier coefficients constitute a representation of the respective section of the baseband signal 103 in the frequency domain.

(36) The discrete partial frequency spectrum of the first transformation unit 158 is fed to a first synthesis apparatus element 105.2 of the synthesis apparatus. The discrete partial frequency spectrum of the second transformation unit 157 is fed to a second synthesis apparatus element 105.1 of the synthesis apparatus. The synthesis apparatus elements 105.1, 105.2 can be designed as has been described above in connection with FIGS. 4 to 6. The synthesis apparatus elements 150.1, 150.2 operate in a phase-shifted manner in such a way that the internal signals of the synthesis apparatus elements 150.1, 150.2 of different frequencies are shifted by half of the window length, wherein the window length is the symbol period of the modulation apparatus 102 multiplied by the window length N. The high-frequency, analog single-carrier partial signals generated by the synthesis apparatus elements 105.11, 105.2 are combined to form the high-frequency, analog single-carrier transmission signal 109 by means of a summer, cf. FIG. 8b. In this transmission device 100, no oversampling and no filtering of the baseband signal 103 is required.

(37) FIG. 9 shows a fourth exemplary embodiment of a transmission device 100 for transmitting a high-frequency, analog transmission signal 109, which is formed as a single-carrier transmission signal. In this respect, said transmission device is a transmission device 100 in the form of an RF transmitter for a single-carrier transmission signal. The transmission device 100 has a modulator 102, a circuit arrangement 101 for generating the high-frequency, analog transmission signal 109 and an antenna 112, by means of which the transmission signal 109 is emitted. In the circuit arrangement 101, particular measures have been taken to reduce undesired effects on the quality of the transmission signal 109. The transmission device 100 according to the third exemplary embodiment uses an additional method step, which precedes the calculation of the discrete frequency spectrum and is also referred to as windowing.

(38) The analysis apparatus 104 of the circuit arrangement 101 is configured as an apparatus for discrete Fourier transformation and has a plurality of, in particular two, transformation units 157, 158. Respective sections of the baseband signal 103 are fed to each of said transformation units 157, 158, which sections correspond to a prescribed window width of N symbols. To this end, the modulated, digital baseband signal 103 is delayed in a delay device 150, in particular by a period that corresponds to half of a window width N. The delay device 150 generates a delayed baseband signal 151. The non-delayed baseband signal 103 is fed to a first series-to-parallel converter 153 and the delayed baseband signal 151 is fed to a second series-to-parallel converter 152.

(39) The baseband signals that are paralleled by the series-to-parallel converters 152, 153 are each fed to a windowing unit 154, 155, in which the paralleled baseband signals are weighted using a prescribed window function, cf. FIG. 10a. The prescribed window function is designed in such a way that the amplitudes of the weighted signals at the edges of the respective window tend toward zero. This means that the window function at the edge of the window has a higher attenuation than in the center of the window. This can reduce the occurrence of discontinuities and/or high-frequency interference in the high-frequency analog transmission signal 109.

(40) Before the paralleled baseband signals weighted by the windowing units 154, 155 are fed to the analysis apparatus 104, a displacement operation of the delayed, weighted, paralleled baseband signals takes place in a displacement unit 156. In the displacement unit 156, the window is divided into a first window half and a second window half and the first window half is interchanged with the second window half, cf. FIG. 10a.

(41) The transformation units 157, 158 of the analysis apparatus 104 carry out a discrete Fourier transformation of the respective sections of the baseband signal in parallel. In a first transformation unit 158, the baseband signal paralleled in the first series-to-parallel converter 153 and weighted in a first windowing unit 155 is subjected to a discrete Fourier transformation. In a second transformation unit 157, the baseband signal delayed in the delay unit 150, paralleled in the second series-to-parallel converter 152, weighted in the second windowing unit 154 and processed in the displacement unit 156 is subjected to a discrete Fourier transformation. The transformation units 157, 158 each calculate a discrete partial frequency spectrum, which has N Fourier coefficients. The Fourier coefficients constitute a representation of the respective section of the baseband signal 103 in the frequency domain.

(42) The discrete partial frequency spectra of the transformation units 157, 158 are combined by means of a summer 159, cf. FIG. 10b. The summer 159 generates a discrete frequency spectrum of the baseband signal 103, which is fed to the synthesis apparatus 105. The synthesis apparatus 105 can be designed as has been described above in connection with FIGS. 4 to 6. Only one synthesis apparatus 105 is required. The high-frequency, analog transmission signal 109 generated by the synthesis apparatus 105 is a single-carrier transmission signal having just one carrier. In this transmission device 100, no oversampling and no filtering of the baseband signal 103 is required.

(43) The transmission devices 100 described above for transmitting a high-frequency, analog transmission signal 109, in particular a high-frequency, analog single-carrier transmission signal, have an antenna 112 for transmitting the transmission signal 109 and a synthesis apparatus 105 for generating the high-frequency, analog transmission signal on the basis of a discrete frequency spectrum of a digital, in particular modulated, baseband signal. A circuit arrangement 101, which comprises the synthesis apparatus 105, is provided in each of said transmission devices 100. Said circuit arrangements 101 can be used, for example, to generate a transmission signal, in particular a high-frequency, analog single-carrier transmission signal, according to the standard IEEE 802.11ad (Wireless Gigabit) in a transmission frequency band above 57 GHz, preferably in a range of from 57 GHz to 66 GHz.

LIST OF REFERENCE SIGNS

(44) 1 Transmission device 2 Modulation device 3 Baseband signal 4 Sampling apparatus 5 Low-pass filter 6 RF-DAC 7 Digital-to-analog converter 8 Oscillator 9 Mixer 10 Transmission signal 11 Amplifier 12 Analog filter 13 Antenna 100 Transmission device 101 Circuit arrangement 102 Modulator 103 Digital baseband signal 104 Analysis apparatus 105 Synthesis apparatus 105.1 Synthesis apparatus element 105.2 Synthesis apparatus element 106 Modulation device 109 Continuous, analog transmission signal 110 Amplifying device 111 Analog filter 112 Antenna 116 Signal source 117 Weighting device 118 Mixer 150 Delay unit 151 Delayed baseband signal 152 Series-to-parallel converter 153 Series-to-parallel converter 154 Windowing unit 155 Windowing unit 156 Displacement unit 157 Transformation unit 158 Transformation unit 159 Summer 160 Summer BB Baseband range BW Bandwidth of the baseband signal BW Bandwidth of the transmission signal c.sub.0, c.sub.1, . . . c.sub.N1 Fourier coefficients