Time delay estimation

• US 7,945,408 B2
• Filed: 09/17/2008
• Issued: 05/17/2011
• Est. Priority Date: 09/20/2007
• Status: Active Grant

• Current Assignee: Voxis, Inc. (Topcon Corporation)
• Original Assignee: Voxis, Inc. (Topcon Corporation)
• Inventors: Lewis, Andrew Philip, West, Joseph Newhall, Dimsdale, Jerry Samuel, Gill, Thomas Rahjit Singh
• Primary Examiner(s): TEIXEIRA MOFFAT, JONATHAN CHARLES
• Application Number:
  US12/212,167
• Publication Number:
  US 20090099813A1
• Time in Patent Office: 972 Days
• Field of Search: 702/79
• US Class Current: 702/79
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• CPC Class Codes: G01S 7/4861 Circuits for detection, sampling, integration or read-out
• CPC Class Codes: G01S 7/4865 Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak peak detection in noise, signal conditioning G01S7/487
• CPC Class Codes: G01S 7/4868 Controlling received signal intensity or exposure of sensor
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating
• CPC Class Codes: G04F 10/00 Apparatus for measuring unknown time intervals by electric means

Abstract

A time differential is estimated between a plurality of signals by determining a filter response of a first electrical signal with a first filter array, determining a filter response of a second electrical signal with a second filter array, and determining, based at least on the filter response of the first electrical signal and the filter response of the second electrical signal, a time differential between the first electrical signal and the second electrical signal. A first optical signal is converted into the first electrical signal and a second optical signal is converted into the second electrical signal. The filter response of the first electrical signal and the filter response of the second electrical signal are sampled and the time differential between the first electrical signal and the second electrical signal is determined based at least on the sampled filter response of the first electrical signal and the sampled filter response of the second electrical signal.

Claims

1. A method of estimating a time differential between a plurality of signals comprising:

determining a filter response of a first electrical signal with a first filter array comprising a first plurality of bandpass filters;

determining a filter response of a second electrical signal with a second filter array comprising a second plurality of bandpass filters;

amplifying the second electrical signal;

determining a filter response of the amplified second electrical signal with a third filter array;

selecting either the filter response of the second electrical signal or the filter response of the amplified second electrical signal for determining a time differential; and

determining, based at least on the filter response of the first electrical signal and the selected filter response, a time differential between the first electrical signal and the second electrical signal.

2. The method of claim 1 further comprising:

converting a first optical signal into the first electrical signal; and

converting a second optical signal into the second electrical signal.

3. The method of claim 1 further comprising:

sampling the filter response of the first electrical signal;

sampling the selected filter response; and

wherein the time differential between the first electrical signal and the second electrical signal is determined based at least on the sampled filter response of the first electrical signal and the sampled selected filter response.

4. An apparatus for estimating a time differential between a plurality of signals comprising:

a first filter array comprising a first plurality of bandpass filters adapted to determine a filter response of a first electrical signal;

a second filter array comprising a second plurality of bandpass filters adapted to determine a filter response of a second electrical signal;

an amplifier adapted to amplify the second electrical signal;

a third filter array adapted to determine a filter response of the amplified second electrical signal;

a switch adapted to select either the filter response of the second electrical signal or the filter response of the amplified second electrical signal for determining a time differential; and

a processor adapted to determine, based at least on the filter response of the first electrical signal and the selected filter response, a time differential between the first electrical signal and the second electrical signal.

5. The apparatus of claim 4 further comprising:

a sensor adapted to convert a first optical signal into the first electrical signal; and

to convert a second optical signal into the second electrical signal.

6. The apparatus of claim 4 further comprising:

a first sampler adapted to sample the filter response of the first electrical signal;

a second sampler adapted to sample the selected filter response; and

wherein the processor is further adapted to determine the time differential between the first electrical signal and the second electrical signal based at least on the sampled filter response of the first electrical signal and the sampled selected filter response.