Wideband digital spectrometer

• US 9,020,079 B2
• Filed: 08/15/2013
• Issued: 04/28/2015
• Est. Priority Date: 05/23/2007
• Status: Active Grant

• Current Assignee: Hypres, Inc.
• Original Assignee: Hypres, Inc.
• Inventors: Gupta, Deepnarayan
• Primary Examiner(s): Tran, Khanh C
• Application Number:
  US13/967,488
• Publication Number:
  US 20140286465A1
• Time in Patent Office: 621 Days
• Field of Search: 375/316, 375/340, 375/346, 375/350, 375/343, 708/300, 708/303, 708/322
• US Class Current: 375/343
• CPC Class Codes: H04B 1/0028 wherein the AD/DA conversion occurs at baseband stage
• CPC Class Codes: H04B 1/109 by improving strong signal performance of the receiver when strong unwanted signals are present at the receiver input
• CPC Class Codes: H04B 1/123 using adaptive balancing or compensation means adaptive filter circuits and algorithms H03H
• CPC Class Codes: H04B 1/38 Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving

Abstract

A processor, comprising a first data input configured to receive a stream of samples of a first signal having a spectral space, the stream having a data rate of at least 4 GHz; a second data input configured to receive a stream of samples of a second signal; a multitap correlator, configured to receive the first stream of samples and the second stream of samples, and producing at least one correlation output for each respective sequential sample of the first signal received; and a programmable control configured to alter a relationship of the stream of samples of the first signal and the stream of samples of the second signal, to thereby select, under program control, an alterable correlation output.

Claims

1. A signal processing system, comprising:

(a) a first digitizer, configured to process an analog signal within a band having at least one information-carrying component and at least one additional component, the additional component having different spectral characteristics from the at least one information carrying component, and to produce a digitized signal in dependence thereon;

(b) a digital signal processor comprising at least one shift register and at least one multiplier, configured to spectrally transform the digitized signal, to generate therefrom a data set representing spectral signal characteristics of the digitized signal, and to selectively produce a control signal dependent on the spectral signal characteristics;

(c) an analog signal processor, configured to receive the control signal, and the analog signal, and to produce at least one modified analog output signal based thereon, to selectively alter a relationship between the at least one information-carrying component and at least one additional component, substantially without intermodulation distortion products of the analog signal within the band.

2. The signal processing system according to claim 1, wherein the first digitizer comprises a superconducting analog to digital modulator.

3. The signal processing system according to claim 1, wherein the digital signal processor comprises a digital cross correlator.

4. The signal processing system according to claim 1, wherein the digital signal processor comprises a digital cross correlator and a digital processor configured to perform a signal transform based on the cross correlation of the digitized signal.

5. The signal processing system according to claim 4, wherein the signal transform comprises a frequency domain transform, and wherein the analog signal processor receives the control signal in dependence on at least one frequency transform domain characteristic of the time-continuous signal, the control signal selectively altering a transfer function of an analog filter, to selectively attenuate the at least one additional component while preserving an amplitude of the at least one information carrying component.

6. The signal processing system according to claim 1, wherein the analog signal processor comprises a plurality of frequency selective filters, and wherein characteristics of the frequency selective filters are determined by the digital signal processor based on frequency components of the analog signal to implement an adaptive analog filter bank which selectively attenuates the at least one additional component,

further comprising a second digitizer,

the first digitizer having a first saturation amplitude greater than a second saturation amplitude the second digitizer,

the digital signal processor being configured to estimate a spectral characteristic of the at least one additional component, and to produce the control signal to control the analog signal processor to attenuate the at least one additional component, and

the second digitizer is configured to digitize the at least one modified analog output signal substantially without interference from the at least one additional component.

7. The signal processing system according to claim 1, wherein the first digitizer, at least a portion of the digital signal processor, and at least a portion of the analog signal processor each comprise superconducting circuits.

8. A spectrometer, comprising:

an input configured to receive a wideband radio frequency signal within a frequency band comprising a frequency of at least 500 MHz having an information-carrying signal component and an interfering signal component;

an analog filter having a frequency-selective transfer function without substantial nonlinearity controlled in dependence on a filter control signal to selectively attenuate the interfering signal component with respect to the information-carrying signal component and to produce a filtered signal substantially without intermodulation distortion within the frequency band;

a wideband signal digitizer, having a sampling rate of at least twice a highest frequency of the frequency band and a saturation amplitude, receiving the filtered signal, and being configured to produce a digitized representation of the filtered signal, wherein the interfering signal component has sufficient amplitude to saturate the wideband signal digitizer and thereby cause non-linear distortion in an output of the digitized representation of the filtered signal, and the analog filter is configured to sufficiently attenuate the interfering signal component to avoid saturation of the wideband signal digitizer;

a digital processor, configured to adaptively estimate spectral characteristics of the interfering signal component with respect to an initial estimate and changes over time; and

a filter control, configured to control the transfer function of the analog filter in dependence on at least the computed spectral characteristics.

9. The spectrometer according to claim 8, wherein the digital processor receives data from the wideband signal digitizer at a rate of at least 1 GHz, and the digital processor comprises a digital cross correlator.

10. The spectrometer according to claim 9, wherein the digital processor comprises a shift register.

11. A signal processing system, comprising:

(a) a digitizer, configured to digitize a received analog signal within a band comprising a frequency of at least 500 MHz, above a Nyquist rate of the band, and having at least one information-carrying signal component and at least one additional signal component having spectral characteristics which are time-varying, the additional signal component having different spectral characteristics from the at least one information carrying signal component, and to produce a digitized signal in dependence thereon;

(b) a digital signal processor comprising at least one shift register configured to analyze changes in spectral characteristics of the digitized signal over time, and to selectively produce a time-varying analog filter control signal dependent on the analyzed changes in the spectral characteristics over time, for selectively attenuating the at least one additional signal component having spectral characteristics which are time-varying, with respect to the at least one information carrying signal component; and

(c) an analog filter, configured to receive the time-varying analog filter control signal, and the analog signal, and to produce a filtered output having the at least one additional signal component having spectral characteristics which are time-varying attenuated with respect to the at least one information carrying signal component, wherein the filtered output is substantially without intermodulation distortion products of the received analog signal within the band.

12. The signal processing system according to claim 11, wherein the digitizer comprises a superconducting analog to digital modulator.

13. The signal processing system according to claim 11, wherein the digital signal processor comprises at least one Josephson junction.

14. The signal processing system according to claim 11, wherein the digital signal processor comprises a shift register and a plurality of multipliers.

15. The signal processing system according to claim 11, wherein the digital signal processor comprises a digital cross correlator and is configured to perform a signal transform employing a cross correlation of the digitized signal,

wherein the signal transform comprises a frequency domain transform, and

wherein the analog filter comprises an analog filter bank.

16. The signal processing system according to claim 11, wherein the digitizer samples the received analog signal a sampling rate of at least 40 gigasamples per second.

17. The signal processing system according to claim 11, wherein the digital signal processor comprises a digital cross correlator.

18. The signal processing system according to claim 11, wherein the digitizer comprises at least one of a delta and a delta-sigma type digitizer.

19. The signal processing system according to claim 11, wherein the analog filter comprises at least one low temperature superconducting switch and at least one inductor.