ESTIMATION OF TIME DIFFERENCE OF ARRIVAL (TDOA) IN MULTIPATH ENVIRONMENTS BASED ON SUB-NYQUIST RATE SAMPLING

• US 20140247187A1
• Filed: 08/30/2012
• Published: 09/04/2014
• Est. Priority Date: 08/30/2012
• Status: Abandoned Application

• Current Assignee: Keysight Technologies, Inc.
• Original Assignee: Agilent Technologies, Inc.
• Inventors: HARADA, Koji
• Application Number:
  US13/599,166
• Publication Number:
  US 20140247187A1
• Time in Patent Office: Days
• US Class Current: 342/465
• CPC Class Codes: G01S 5/0273 using multipath or indirect path propagation signals in position determination

Abstract

A method is provided for to determining a time difference of arrival (TDOA) between a first signal and a second signal. The method includes sampling a first signal at a sub-Nyquist rate to provide a first sampled signal; sampling a second signal at the sub-Nyquist rate to provide a second sampled signal, the first and second signals representing corresponding multipath channels; cross-correlating the first and second sampled signals; and determining an estimate of the TDOA between the first and second signals based on the sampled first and second signals.

Claims

1. A method for estimating time difference of arrival (TDOA) between first and second multipath signals, where each of the first and second signals represents a multipath channel, the comprising:

sampling the first signal at a sub-Nyquist rate to provide a first sampled signal;

sampling the second signal at the sub-Nyquist rate to provide a second sampled signal;

cross-correlating the first and second sampled signals; and

determining an estimate of the TDOA between the first and second signals based on the cross-correlated first and second sampled signals.

2. The method of claim 1, further comprising:

refining the estimate of the TDOA based on a nonlinear least square (NLS) estimate.

3. The method of claim 1, wherein sampling the first and second signals and cross-correlating the first and second sampled signals comprise innovation rate sampling (IRS).

4. The method of claim 1, wherein sampling the first signal comprises lowpass filtering the first signal to provide a first band limited signal and digitizing the first band limited signal, and wherein sampling the second signal comprises lowpass filtering the second signal to provide a second band limited signal and digitizing the second band limited signal.

5. The method of claim 1 wherein each of the first and second signals are sampled at a rate less than a Nyquist rate and greater than or equal to an innovation rate.

6. The method of claim 1, further comprising:

downconverting each of the first and second signals.

7. The method of claim 1, wherein determining the estimate of the TDOA comprises performing an annihilating filter method.

8. The method of claim 7, wherein the annihilating filter method comprises a parametric estimation method for line spectra with super-resolution capability.

9. A method, instantiated in a computer readable medium storing programming instructions and executable by a processor, to determine time difference of arrival (TDOA) between a first signal and a second signal, the method comprising:

sampling a first signal at a sub-Nyquist rate to provide a first sampled signal;

sampling a second signal at the sub-Nyquist rate to provide a second sampled signal, the first and second signals representing corresponding multipath channels of an input signal from a transmitter;

cross-correlating the first and second sampled signals; and

determining an estimate of the TDOA between the first signal and the second signal based on the cross-correlated first and second sampled signals.

10. The method of claim 9, further comprising:

refining the estimate of the TDOA based on a nonlinear least square (NLS) estimate.

11. The method of claim 9, wherein sampling the first and second signals and cross-correlating the first and second sampled signals comprise innovation rate sampling (IRS).

12. The method of claim 9, wherein sampling the first signal and sampling the second signal each occurs at a rate less than a Nyquist rate and greater than or equal to an innovation rate.

13. An apparatus, comprising:

a first device configured to sample a first signal from a first sensor at a sub-Nyquist rate to provide a first sampled signal;

a second device configured to sample a second signal from a second sensor at the sub-Nyquist rate to provide a second sampled signal; and

a module configured to cross-correlate the first and second sampled signals and to provide estimates of time difference of arrival (TDOA) between the first and second signals corresponding to a sampling period based on the cross-correlated first and second sampled signals,

wherein the first and second signals correspond to an input signal from a transmitter.

14. The apparatus of claim 13, further comprising:

a first input node configured to receive the first signal from the first sensor; and

a second input node configured to receive the second signal from the second sensor, the second sensor being at a different geographic location than the first sensor.

15. The apparatus of claim 13, further comprising:

another module configured to receive the estimates of the TDOA and to further refine the estimates of the TDOA based on nonlinear least square (NLS) estimates.

16. The apparatus of claim 13, wherein each of the first signal and the second signal is sampled and cross-correlation is performed by innovation rate sampling (IRS).

17. The apparatus as claimed in claim 13, wherein each of the first signal and the second signal is sampled at a rate less than a Nyquist rate and greater than or equal to an innovation rate.

18. The apparatus of claim 13, wherein the first device comprises a first lowpass filter and a first analog-to-digital converter (ADC), the first lowpass filter being configured to receive the first signal and to provide a first band limited signal to the first ADC;

and

wherein the second device comprises a second lowpass filter and a second ADC, the second lowpass filter being configured to receive the second signal and to provide a second band limited signal to the second ADC.

19. The apparatus of claim 15, further comprising:

a processor configured to determine a location of the transmitter using the refined TDOA estimates.

20. The apparatus of claim 15, wherein each of the module and the other module is implemented by one or more computer processors.