Signal processing systems and signal processing methods

• US 10,355,705 B2
• Filed: 11/18/2015
• Issued: 07/16/2019
• Est. Priority Date: 11/18/2015
• Status: Active Grant

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V., Technische Universitã¤T Berlin (Tu)
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Schmidt, Christian, Kottke, Christoph, Jungnickel, Volker, Hilt, Jonas
• Primary Examiner(s): Anwar, Mohammad S
• Application Number:
  US15/568,481
• Publication Number:
  US 20180159548A1
• Time in Patent Office: 1,336 Days
• CPC Class Codes: G06G 7/19 for forming integrals of products, e.g. Fourier integrals, Laplace integrals, correlation integrals; for analysis or synthesis of functions using orthogonal functions Fourier or spectrum analysis G01R23/16; sound analysis or synthesis G10L
• CPC Class Codes: G06G 7/26 Arbitrary function generators using Fourier series or other orthogonal functions G06G7/19; using curve followers G06K11/02
• CPC Class Codes: H03M 1/1009 Calibration
• CPC Class Codes: H03M 1/1038 by storing corrected or correction values in one or more digital look-up tables H03M1/1057 takes precedence
• CPC Class Codes: H03M 1/662 Multiplexed conversion systems
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0837 using pre-detection combining H04B7/0868 takes precedence
• CPC Class Codes: H04J 1/12 Arrangements for reducing cross-talk between channels in line transmission systems H04B3/32; in cables or lines H04B3/26 - H04B3/30
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 27/2096 Arrangements for directly or externally modulating an optical carrier optical modulation H04B10/503

Abstract

It is provided a signal processing system, comprising at least a first, a second and a third digital-to-analog converter (DAC); a processing unit configured for splitting a sampled signal into a first and a second signal corresponding to different frequency portions of the sampled signal, transmitting the first signal to the first DAC, splitting the second signal into a first and a second subsignal and transmitting the first subsignal to the second DAC and the second subsignal to the third DAC, the first subsignal corresponding to the real part of the second signal and the second subsignal corresponding to the imaginary part of the second signal; an IQ mixer configured for mixing an analog output signal of the second DAC and an analog output signal of the third DAC and a combiner for combining an analog output signal of the first DAC and an output signal of the IQ mixer.

Claims

1. A signal processing system, comprising

at least a first, a second and a third digital-to-analog converter (DAC);

a processing unit configured for splitting a sampled signal into at least a first and a second signal corresponding to different frequency portions of the sampled signal, transmitting the first signal to the first DAC, splitting the second signal into a first and a second sub signal and transmitting the first sub signal to the second DAC and the second subsignal to the third DAC, the first subsignal corresponding to the real part of the second signal and the second sub signal corresponding to the imaginary part of the second signal;

an IQ mixer configured for mixing an analog output signal of the second DAC and an analog output signal of the third DAC;

a combiner for combining an analog output signal of the first DAC and an output signal of the IQ mixer.

2. The system as claimed in claim 1, wherein the frequency portion that corresponds to the first signal comprises lower frequencies than the frequency portion that corresponds to the second signal.

3. The system as claimed in claim 1, wherein the processing unit is configured for carrying out the splitting of the sampled signal into the first and the second signal in the frequency domain.

4. The system as claimed in claim 1, wherein the processing unit is configured for carrying out the splitting of the sampled signal into the first and the second signal in the time domain.

5. The system as claimed in claim 1, wherein the processing unit is configured for carrying out a Fourier transform of the second signal for generating the first and the second subsignal.

6. The system as claimed in claim 1, further comprising at least one low pass filter for filtering the outputs of the DACs and/or a band pass or a low pass or a high pass filter for filtering the output of the IQ mixer.

7. The system as claimed in claim 1, wherein the processing unit is realized by a digital signal processor.

8. The system as claimed in claim 1, wherein the IQ mixer is configured for single sideband modulation.

9. The system as claimed in claim 1, wherein the IQ mixer is realized by an opto-electronic modulator.

10. A signal processing method, in particular using the system according to claim 1, the method comprising the steps of:

providing at least a first and a second digital-to-analog converter (DAC);

splitting a sampled signal into at least a first and a second signal corresponding to different frequency portions of the sampled signal by means of a processing unit;

pre-equalizing the first and the second signal;

converting the pre-equalized first signal into a first analog signal using the first DAC;

converting the pre-equalized second signal into a second analog signal using the second DAC;

combining the first and the second analog signal using a combiner,

wherein the processing unit, the first DAC and the combiner define a first processing channel,

wherein the processing unit, the second DAC and the combiner define a second processing channel,

wherein the pre-equalized first signal is generated by processing the first signal in such a way that the pre-equalized first signal compensates cross talk between the first and the second processing channel, and/or the pre-equalized second signal is generated by processing the second signal in such a way that the pre-equalized second signal compensates cross talk between the first and the second processing channel.

11. The method as claimed in claim 10, wherein generating the pre-equalized first and second signal is carried out using the results of a calibration measurement with respect to at least a spatial, frequency and/or time portion of the first and/or the second processing channel.

12. The method as claimed in claim 11, wherein the calibration measurement is carried out using a channel estimation scheme with respect to the first and/or the second processing channel.

13. The method as claimed in claim 12, wherein the channel estimation scheme comprises treating the combination of the first and the second processing channel as a MIMO system.

14. The method as claimed in claim 13, wherein the calibration measurement comprises determining coefficients of a frequency response matrix related to the MIMO system.

15. The method as claimed in claim 12, wherein the channel estimation scheme comprises transmitting a channel estimation sequence to the first and/or the second DAC.

16. The method as claimed in claim 15, wherein a first channel estimation sequence is transmitted to the first DAC and a second channel estimation sequence is transmitted to the second DAC, wherein the first channel estimation sequence is distinguishable from the second channel estimation sequence.

17. The method as claimed in claim 11, wherein the calibration measurement comprises an S- and/or X-parameter measurement of at least a part of an analog section of the first and/or the second processing channel.

18. The method as claimed in claim 10, wherein the pre-equalized first and second signal are generated adaptively by means of the results of re-calibration measurements carried out using a portion of an analog signal produced by the combiner.

19. The method as claimed in claim 10, further comprising creating an oversampled first signal and converting the oversampled first signal by the first DAC in order to obtain the first analog signal and/or creating an oversampled second signal and converting the oversampled second signal by the second DAC in order to obtain the second analog signal.

20. A signal processing system, in particular for carrying out the method according to claim 10, the system comprising:

a processing unit configured for splitting a sampled signal into at least a first and a second signal corresponding to different frequency portions of the sampled signal;

a pre-equalizing unit for pre-equalizing the first and the second signal;

at least a first digital-to-analog converter (DAC) for converting the pre-equalized first signal into a first analog signal and a second DAC for converting the pre-equalized second signal into a second analog signal;

a combiner for combining the first and the second analog signal,

wherein the processing unit, the first DAC and the combiner define a first processing channel,

wherein the processing unit, the second DAC and the combiner define a second processing channel,

wherein pre-equalizing unit is configured for generating the pre-equalized first signal by processing the first signal in such a way that the pre-equalized first signal compensates cross talk between the first and the second processing channel, and/or for generating the pre-equalized second signal by processing the second signal in such a way that the pre-equalized second signal compensates cross talk between the first and the second processing channel.