Method and device for measuring the phase-noise spectrum of a pulsed sinusoidal signal

Patent metadata

Field	Value
Publication number	US-9244106-B2
Application number	US-201213883727-A
Country	US
Kind code	B2
Filing date	Jan 5, 2012
Priority date	Feb 23, 2011
Publication date	Jan 26, 2016
Grant date	Jan 26, 2016

Abstract

A device for measuring the phase-noise spectrum of a pulsed sinusoidal signal generates a pulsed sinusoidal signal, converts the analog pulsed sinusoidal signal into a corresponding digital, pulsed sinusoidal signal and mixes the digital, pulsed sinusoidal signal into the baseband by means of quadrature mixing. Following this, the phase of the pulsed sinusoidal signal in the baseband is determined by means of Fourier transform of the phase of the pulsed sinusoidal signal, the phase spectrum of the pulsed sinusoidal signal is determined, and the phase-noise spectrum of the pulsed sinusoidal signal is determined by removing the spectral lines associated with the sinusoidal signal from the phase spectrum. According to the invention, the pulse pauses are removed from the pulsed sinusoidal signal in the baseband.

First claim

The invention claimed is:

1. A method for measuring the phase-noise spectrum of a pulsed sinusoidal signal with the following method steps:
generating a pulsed digital sinusoidal signal,
quadrature mixing the pulsed sinusoidal signal into the baseband,
determining the phase of the pulsed sinusoidal signal in the baseband,
determining the phase spectrum of the pulsed sinusoidal signal by means of Fourier transform of the phase of the pulsed sinusoidal signal in the baseband,
determining the phase-noise spectrum of the pulsed sinusoidal signal by removing the spectral lines associated with the sinusoidal signal from the phase spectrum,
wherein the pulse pauses are also removed from the pulsed sinusoidal signal in the baseband.

2. The method according to claim 1 ,
wherein
the removal of pulse pauses from the pulsed sinusoidal signal by cutting out the pulse pauses from the pulsed sinusoidal signal is implemented in the time domain.

3. The method according to claim 1 ,
wherein
the removal of pulse pauses from the pulsed sinusoidal signal comprises the following method steps to be implemented iteratively:
zeroing signal values in the pulse pauses of the pulsed sinusoidal signal,
determining an anticipated value for the start of the pulse and of a displacement time-interval for every pulse of the pulsed sinusoidal signal to be time-displaced,
determining a spectrum associated with each pulse,
displacing the phase of the respective spectrum corresponding to the displacement time-interval of the respective pulse and
determining the respective time-displaced pulse by means of inverse Fourier transform of the phase-displaced spectrum associated with the respective pulse and
buffering the respective time-displaced pulse.

4. The method according to claim 1 ,
wherein
the generated, pulsed sinusoidal signal is split into a first pulsed sinusoidal signal and a second pulsed sinusoidal signal identical to the first pulsed sinusoidal signal, the method steps of the quadrature mixing, removal of the pulse pauses and determination of the phase are each implemented separately for the first and second pulsed sinusoidal signal, and the phase spectrum of the pulsed sinusoidal signal is determined by means of cross-correlation and subsequent Fourier transform of the phase of the first and second pulsed sinusoidal signal in the baseband.

5. The method according to claim 1 ,
wherein
the Dirac impulses occurring in the phase-noise spectrum, which result from instabilities in the course of the phase of the pulsed sinusoidal signal with pulse pauses eliminated or of the first pulsed sinusoidal signal with pulse pauses eliminated or of the second pulsed sinusoidal signal with pulse pauses eliminated, are identified and removed from the phase-noise spectrum by interpolation with adjacent spectral values of the phase-noise spectrum.

6. The method according to claim 1 ,
wherein
an unsteadiness which occurs in the course of the phase of the pulsed sinusoidal signal with pulse pauses eliminated or the first pulsed sinusoidal signal with pulse pauses eliminated or the second pulsed sinusoidal signal with pulse pauses eliminated, is removed by shortening the respectively following pause of the pulsed sinusoidal signal or of the first pulsed sinusoidal signal or of the second pulsed sinusoidal signal until the phase in the respectively preceding pulse of the pulsed sinusoidal signal or of the first pulsed sinusoidal signal or of the second pulsed sinusoidal signal corresponds to the phase in the respectively following pulse of the pulsed sinusoidal signal or of the first pulsed sinusoidal signal or of the second pulsed sinusoidal signal.

7. A device for measuring the phase-noise spectrum of a pulsed sinusoidal signal comprising:
a signal source configured to generate the pulsed sinusoidal signal,
at least one analog-digital converter for the analog-digital conversion of the pulsed sinusoidal signal,
at least one quadrature mixer for the quadrature mixing of the pulsed sinusoidal signal into the baseband,
at least one unit configured to determine the phase of the pulsed sinusoidal signal,
a Fourier transformer configured to determine the phase spectrum of the pulsed sinusoidal signal from the phase of the pulsed sinusoidal signal,
an interpolator configured to determine the phase-noise spectrum of the pulsed sinusoidal signal by cutting out spectral lines associated with the sinusoidal signal from the phase spectrum,
wherein a unit configured to remove pulse pauses from the pulsed sinusoidal signal is arranged upstream of the Fourier transformer.

8. The device according to claim 7 ,
wherein
the unit configured to remove pulse pauses from the pulsed sinusoidal signal provides a ring buffer.

9. The device according to claim 8 ,
wherein
a unit configured to combine signal values occurring in pulses is connected to the ring buffer.

10. The device according to claim 7 ,
wherein
the unit configured to remove pulse pauses from the pulsed sinusoidal signal provides a unit configured to zero signal values occurring in pulse pauses, a unit configured to control a phase modifier, a Fourier transformer configured to determine the spectrum associated with each pulse, a phase modifier configured to displace the phase of the respective spectrum, an inverse Fourier transformer configured to determine the time-displaced pulse associated with the respective phase-displaced spectrum and a ring buffer configured to buffer the individual time-displaced pulses.

11. The device according to claim 7 ,
wherein
a splitter is connected between the signal source and the two analog-digital converters, and a cross-correlator is connected between the two units configured to determine the phase of the pulsed sinusoidal signal and the Fourier transformer.

12. The device according to claim 7 ,
wherein
the interpolator additionally serves to cut out Dirac impulses in the phase-noise spectrum.

Assignees

• Eckert Hagen
• Weiss Martin
• Wendler Wolfgang
• Rohde & Schwarz

Inventors

• Eckert Hagen
• Weiss Martin
• Wendler Wolfgang

Classifications

• G01R25/00

  Arrangements for measuring phase angle between a voltage and a current or between voltages or currents · CPC title

• G01R29/18

  Indicating phase sequence; Indicating synchronism · CPC title

• G01R29/16

  Measuring asymmetry of polyphase networks · CPC title

• G01R29/26 Primary

  Measuring noise figure; Measuring signal-to-noise ratio · CPC title

• G01R19/2513

  Arrangements for monitoring electric power systems, e.g. power lines or loads; Logging · CPC title