DETECTING APPARATUS, CALCULATING APPARATUS, MEASUREMENT APPARATUS, DETECTING METHOD, CALCULATING METHOD, TRANSMISSION SYSTEM, PROGRAM, AND RECORDING MEDIUM

• US 20100266004A1
• Filed: 04/16/2009
• Published: 10/21/2010
• Est. Priority Date: 04/16/2009
• Status: Active Grant

• Current Assignee: Advantest Corporation
• Original Assignee: Advantest Corporation
• Inventors: YAMAGUCHI, Takahiro, DEGAWA, Katsuhiko, AOKI, Takafumi
• Granted Patent: US 8,306,132 B2
• Time in Patent Office: Days
• US Class Current: 375/226
• CPC Class Codes: H04B 3/46 Monitoring; Testing
• CPC Class Codes: H04L 27/0014 Carrier regulation of chaotic carriers H04L27/001; for multicarrier receivers H04L27/2657

Abstract

Provided is a detection apparatus that detects a phase alignment error between transmission signals transmitted on different channels, comprising a correlation calculating section that calculates a cross-spectrum between the transmission signals based on a result of a measurement of the transmission signals transmitted in the channels; a phase difference calculating section that calculates a phase difference spectrum between the transmission signals based on the cross-spectrum calculated by the correlation calculating section; and a detecting section that detects a difference between transmission times of the transmission signals transmitted on the different channels and a phase offset between the transmission signals, based on the phase difference spectrum calculated by the phase difference calculating section.

Claims

1. A detection apparatus that detects a phase alignment error between transmission signals transmitted on different channels, comprising:

a correlation calculating section that calculates a cross-spectrum between the transmission signals based on a result of a measurement of the transmission signals transmitted in the channels;

a phase difference calculating section that calculates a phase difference spectrum between the transmission signals based on the cross-spectrum calculated by the correlation calculating section; and

a detecting section that detects a difference between transmission times of the transmission signals transmitted on the different channels and a phase offset between the transmission signals, based on the phase difference spectrum calculated by the phase difference calculating section.

2. The detection apparatus according to claim 1, wherein

the transmission signals have substantially the same spectrum at a prescribed overlapping frequency band, and are input respectively to the channels, and

the correlation calculating section calculates the cross-spectrum between the transmission signals in the prescribed overlapping frequency band.

3. The detection apparatus according to claim 2, wherein the detecting section includes:

a time difference calculating section that calculates the transmission time difference based on a slope of the phase difference spectrum; and

a phase calculating section that calculates the phase offset based on an intercept of the phase difference spectrum.

4. The detection apparatus according to claim 3, wherein

the time difference calculating section and the phase calculating section detect the transmission time difference and the phase offset based on the slope and the intercept of the phase difference spectrum, which is unwrapped by sequentially adding 2π

at prescribed frequencies.

5. The detection apparatus according to claim 4, wherein

the detecting section further includes a frequency bin selecting section that selects components of at least two frequency bins in the phase difference spectrum,

the frequency bin selecting section selects, from among the at least two selected frequency bin components of the phase difference spectrum, at least two frequency bins having the highest signal to noise ratio, and

the time difference calculating section and the phase calculating section calculate the slope and the intercept of the phase difference spectrum based on components of the at least two frequency bins selected by the frequency bin selecting section.

6. The detection apparatus according to claim 5, wherein

the time difference calculating section calculates a number of times that 2π

is added, when unwrapping the phase difference spectrum, between two prescribed frequency bins from among the at least two frequency bins selected by the frequency bin selecting section, based on components of the at least two frequency bins, and

the time difference calculating section calculates the slope of the phase difference spectrum based on the components of the two prescribed frequency bin components and the number of times that 2π

is added between the two prescribed frequency bin components.

7. The detection apparatus according to claim 5, wherein

with one prescribed frequency bin from among the frequency bins selected by the frequency bin selecting section as a reference, the time difference calculating section uses a least squares method to calculate (i) a number of times that 2π

is added when unwrapping an other phase difference spectrum based on frequency bins that were not selected and (ii) whether the slope of the other phase difference spectrum is at a minimum value.

8. The detection apparatus according to claim 2, wherein the detecting section includes:

a phase correlation calculating section that calculates a phase-only correlation function by performing an inverse Fourier transform on the phase difference spectrum; and

a time difference calculating section that calculates the difference between the transmission times based on a position of a peak of the phase-only correlation function.

9. The detection apparatus according to claim 8, wherein

the detecting section further includes a phase calculating section that calculates an intercept of the phase difference spectrum, based on the difference between the transmission times calculated by the time difference calculating section, and calculates the phase offset based on the calculated intercept of the phase difference spectrum.

10. The detection apparatus according to claim 8, wherein

the detecting section eliminates a frequency component having a low signal-to-noise ratio from the input phase difference spectrum.

11. The detection apparatus according to claim 2, further comprising a measuring section that samples the transmission signal transmitted on each channel and performs a Fourier transform on sampling results of the transmission signals.

12. The detection apparatus according to claim 2, further comprising a signal sending section that inputs, to each channel, transmission signals having spectra that are substantially the same in a prescribed overlapping frequency band.

18. A transmission system that divides a band of a signal to be transmitted and transmits the divided signals via a plurality of channels, comprising:

a signal sending section that divides a frequency band of the signal to be transmitted such that a portion of frequency bands of the resulting divided transmission signals overlap, and inputs the transmission signals into the channels respectively;

a measuring section that measures the transmission signals transmitted on the channels; and

the detection apparatus according to claim 1 that detects the phase alignment error between the transmission signals measured by the measuring section.

13. A calculation apparatus that calculates, from a phase difference spectrum between two transmission signals, a difference in transmission time between channels on which the transmission signals are respectively transmitted and a phase offset between the transmission signals, comprising:

a frequency bin selecting section that selects components of at least two frequency bins in the phase difference spectrum;

a time difference calculating section that calculates a slope of the phase difference spectrum, based on the components of the at least two frequency bins selected by the frequency bin selecting section, and calculates the difference between the transmission times based on the calculated slope of the phase difference spectrum; and

a phase calculating section that calculates an intercept of the phase difference spectrum, based on the components of the at least two frequency bins selected by the frequency bin selecting section, and calculates the phase offset based on the calculated intercept of the phase difference spectrum

14. A method for detecting a phase alignment error between transmission signals transmitted on different channels, comprising:

calculating a cross-spectrum between the transmission signals based on a result of a measurement of the transmission signals transmitted in the channels;

calculating a phase difference spectrum between the transmission signals based on the calculated cross-spectrum; and

detecting a difference between transmission times of the transmission signals transmitted on the different channels and a phase offset between the transmission signals, based on the calculated phase difference spectrum.

15. A method for calculating, from a phase difference spectrum between two transmission signals, a difference in transmission time between channels on which the transmission signals are respectively transmitted and a phase offset between the transmission signals, comprising:

selecting components of at least two frequency bins in the phase difference spectrum;

calculating a slope of the phase difference spectrum, based on the components of the at least two selected frequency bins, and calculating the difference between the transmission times based on the calculated slope of the phase difference spectrum; and

calculating an intercept of the phase difference spectrum, based on the components of the at least two selected frequency bins, and calculating the phase offset based on the calculated intercept of the phase difference spectrum

16. A program causing a computer to function as a detection apparatus that detects a phase alignment error between transmission signals transmitted on different channels, the program causing the computer to function as:

a correlation calculating section that calculates a cross spectrum between the transmission signals based on a result of a measurement of the transmission signals transmitted in the channels;

a phase difference calculating section that calculates a phase difference spectrum between the transmission signals based on the cross spectrum calculated by the correlation calculating section; and

a detecting section that detects a difference between transmission times of the transmission signals transmitted on the different channels and a phase offset between the transmission signals, based on the phase difference spectrum calculated by the phase difference calculating section.

17. A recording medium storing thereon the program according to claim 16.

19. An AD conversion apparatus comprising:

two AD converters that each detect an amplitude level crossing of a signal, and output the amplitude level at a timing of the detection and the corresponding timing;

an interpolation processing apparatus that converts the two signals output by the AD converters, which have irregular sampling points, into two signals that have regular sampling points;

a correlation calculating section that calculates a cross-spectrum between the two signals having regular sampling points; and

a phase difference calculating section that calculates a phase difference spectrum between the two signals having regular sampling points, based on the cross-spectrum calculated by the correlation calculating section, wherein

the AD conversion apparatus estimates the phase offset and the time difference between the two signals having regular sampling points output by the interpolation processing apparatus, based on the phase difference spectrum calculated by the phase difference calculating section.