Time-aligning a signal

1. A method comprising:

obtaining sinusoidal signals comprising components of a first time-domain signal;

shifting phases of the sinusoidal signals by amounts corresponding to a specified time-shift to produce phase-shifted signals, wherein shifting the phases is performed to more closely align an envelope of the first time-domain signal with an envelope of a second time-domain signal, and wherein the second time-domain signal comprises a variable power signal; and

converting the phase-shifted signals to time domain signals having the specified time-shift;

wherein the sinusoidal signals comprise a first harmonic and additional harmonics, each additional harmonic corresponding to an integer times a frequency of the first harmonic; and

wherein, for each additional harmonic, a phase-shift corresponds to a phase-shift of the first harmonic times the integer.

2. The method of claim 1 , wherein obtaining the sinusoidal signals comprises performing a frequency-domain analysis of the first time-domain signal.

3. The method of claim 2 , wherein the frequency-domain analysis comprises of a discrete Fourier transform.

4. The method of claim 2 , wherein the frequency-domain analysis comprises one of a Galois transform, a Cosine transform, or a ChirpZ transform.

5. The method of claim 1 , wherein obtaining the sinusoidal signals comprises performing a fast Fourier transform of the first time-domain signal to produce the sinusoidal signals;

wherein the variable power signal is produced by a variable power supply; and

wherein converting comprises performing an inverse fast Fourier transform on the phase-shifted signals to produce a third time-domain signal having an envelope that tracks the envelope of the variable power signal more closely than does the envelope of the first time-domain signal resulting in a reduction of wasted power from the variable power supply.

6. The method of claim 1 , wherein shifting phases of the sinusoidal signals by amounts corresponding to a specified time-shift comprises delaying the phases of the sinusoidal signals by the amounts.

7. The method of claim 1 , wherein shifting phases of the sinusoidal signals by amounts corresponding to a specified time-shift comprises advancing the phases of the sinusoidal signals by the amounts.

8. The method of claim 1 , wherein the sinusoidal signals are associated with bins, each of the bins having a bin number that is based on the integer;

wherein a Fourier frequency of the time-domain signal is an inverse of an acquisition time of the time-domain signal; and

wherein shifting phases of the sinusoidal signals comprises:

generating a ramp function having a slope that corresponds to a phase delay of the Fourier frequency, the ramp function comprising steps in which each step of the ramp function corresponds to a product of the bin number and the phase delay; and

combining the ramp function with phases of the sinusoidal signals to produce the phase-shifted signals.

9. The method of claim 8 , wherein each step has an equal length.

10. The method of claim 1 , wherein the first time-domain signal has an associated sample clock period; and

wherein the specified time-shift is less than the sample clock period.

11. The method of claim 1 , wherein the first time-domain signal has an associated sample clock period; and

wherein the specified time-shift is more than the sample clock period.

12. The method of claim 1 , wherein the sinusoidal signals are two signals.

13. The method of claim 1 , wherein the sinusoidal signals comprise more than two signals.

14. The method of claim 1 , wherein the first time-domain signal is generated by a first waveform generator.

15. The method of claim 14 , wherein the second time-domain signal is generated by a second waveform generator.

16. The method of claim 1 , wherein the first time-domain signal passes through a different electrical pathway than the second time-domain signal resulting in a difference between the envelope of the first time-domain signal and the envelope of the second time domain signal that is mitigated by the shifting.

17. A method comprising:

obtaining sinusoidal signals comprising components of a first time-domain signal;

shifting phases of the sinusoidal signals by amounts corresponding to a specified time-shift to produce phase-shifted signals, wherein shifting the phases is performed to more closely align an envelope of the first time-domain signal with an envelope of a second time-domain signal, and wherein the second time-domain signal comprises a variable power signal; and

converting the phase-shifted signals to time domain signals having the specified time-shift;

wherein the sinusoidal signals are associated with bins, each of the bins having a bin number that is based on an integer;

wherein a phase-shift for a sinusoidal signal corresponds to a product of two, pi, a time-shift for the sinusoidal signal, and a bin number for the sinusoidal signal divided by a total period of the first time-domain signal.

18. One or more non-transitory machine-readable storage devices storing instructions that are executable by one or more processing devices to perform operations comprising:

obtaining information representing sinusoidal signals comprising components of a first time-domain signal;

processing the information to shift phases of the sinusoidal signals by amounts corresponding to a specified time-shift to produce information representing phase-shifted signals, wherein shifting the phases is performed to more closely align an envelope of the first time-domain signal with an envelope of a second time-domain signal, and wherein the second time-domain signal comprises a variable power signal; and

processing the information representing the phase-shifted signals to produce information representing time domain signals having the specified time-shift;

wherein the sinusoidal signals comprise a first harmonic and additional harmonics, each additional harmonic corresponding to an integer times a frequency of the first harmonic; and

wherein, for each additional harmonic, a phase-shift corresponds to a phase-shift of the first harmonic times the integer.

19. A system comprising:

one or more processing devices; and

one or more non-transitory machine-readable storage devices storing instructions that are executable by the one or more processing devices to perform operations comprising:

obtaining information representing sinusoidal signals comprising components of a first time-domain signal;

processing the information to shift phases of the sinusoidal signals by amounts corresponding to a specified time-shift to produce information representing phase-shifted signals, wherein shifting the phases is performed to more closely align an envelope of the first time-domain signal with an envelope of a second time-domain signal, and wherein the second time-domain signal comprises a variable power signal; and

processing the information representing the phase-shifted signals to produce information representing time domain signals having the specified time-shift;

wherein the sinusoidal signals comprise a first harmonic and additional harmonics, each additional harmonic corresponding to an integer times a frequency of the first harmonic; and

wherein, for each additional harmonic, a phase-shift corresponds to a phase-shift of the first harmonic times the integer.

20. The one or more non-transitory machine-readable storage devices of claim 18 , wherein obtaining the sinusoidal signals comprises performing a fast Fourier transform of the first time-domain signal to produce the sinusoidal signals;

wherein the variable power signal is produced by a variable power supply; and

wherein converting comprises performing an inverse fast Fourier transform on the phase shifted signals to produce a third time-domain signal having an envelope that tracks the envelope of the variable power signal more closely than does the envelope of the first time-domain signal resulting in a reduction of wasted power from the variable power supply.

21. The system claim 19 , wherein obtaining the sinusoidal signals comprises performing a fast Fourier transform of the first time-domain signal to produce the sinusoidal signals;

wherein the variable power signal is produced by a variable power supply; and

wherein converting comprises performing an inverse fast Fourier transform on the phase shifted signals to produce a third time-domain signal having an envelope that tracks the envelope of the variable power signal more closely than does the envelope of the first time-domain signal resulting in a reduction of wasted power from the variable power supply.