Leading edge detection
A leading edge associated with a received signal is detected to provide, for example, time of arrival information for a ranging algorithm. In some aspects, a method of leading edge detection involves sampling a received signal, generating a drift compensated signal based on the samples, reconstructing the received signal based on the drift compensated signal, and identifying a leading edge associated with the received signal based on the reconstructed signal.
1. A method of leading edge detection, comprising:
receiving a signal, wherein the signal comprises a multipath spread pulse including a plurality of lobes;
sampling the received signal to generate samples;
generating a drift compensated signal based on the samples;
reconstructing the received signal based on the drift compensated signal; and
identifying a leading edge associated with the received signal based on the reconstructed signal, wherein identifying the leading edge comprises identifying an earliest received one of the plurality of lobes.
2. The method of claim 1 , further comprising:
increasing resolution of the samples to generate higher resolution samples,
wherein the generation of the drift compensated signal comprises time shifting the higher resolution samples.
3. The method of claim 2 , wherein the time shifting of the higher resolution samples is performed at a timing resolution that is higher than a timing resolution of the sampling.
4. The method of claim 2 , wherein the increasing of the resolution comprises zero insertion.
5. The method of claim 1 , wherein the identification of the leading edge employs an interpolation window having a length that is based on a maximum pulse width associated with the received signal.
6. A method of leading edge detection, comprising:
receiving a signal, wherein the received signal comprises a plurality of pulses;
sampling the received signal to generate samples, wherein the samples comprise a plurality of sample sets associated with the pulses;
generating a drift compensated signal based on the samples, wherein the generation of the drift compensated signal comprises time shifting at least one of the sample sets;
reconstructing the received signal based on the drift compensated signal, wherein the reconstructing of the received signal comprises summing the sample sets after the time shifting; and
identifying a leading edge associated with the received signal based on the reconstructed signal.
7. The method of claim 6 , wherein the reconstructing of the received signal further comprises performing a thresholding operation to eliminate any isolated elements from the summation of the sample sets.
8. The method of claim 1 , wherein the reception of the signal comprises:
determining a noise level of a communication channel used for receiving the signal; and
setting a gain used for receiving the signal based on the noise level.
9. The method of claim 1 , wherein the sampling comprise one-bit quantization.
10. The method of claim 1 , wherein:
the identification of the leading edge comprises estimating a time of arrival of the leading edge; and
the method further comprises determining a distance between an apparatus that receives the signal and another apparatus based on the estimated time of arrival.
11. A method of leading edge detection, comprising:
receiving a signal, wherein the received signal comprises a set of pulses;
sampling the received signal to generate samples;
generating a drift compensated signal based on the samples;
reconstructing the received signal based on the drift compensated signal;
identifying a leading edge associated with the received signal based on the reconstructed signal;
generating a drift compensated clock signal, wherein the generation of the samples is based on the drift compensated clock signal;
estimating a residual drift associated with the set of pulses;
determining timing of the leading edge; and
adjusting the timing based on the residual drift.
12. The method of claim 11 , wherein:
the generation of the drift compensated clock signal comprises adjusting the drift compensated clock signal for clock drift according to a first timing resolution;
the adjustment of the timing is made according to a second timing resolution that is higher than the first timing resolution; and
the adjustment of the timing according to the second timing resolution compensates for residual drift error associated with at least one clock drift adjustment made according to the first timing resolution.
13. The method of claim 11 , wherein the estimating of the residual drift comprises:
determining a set of drift estimates corresponding to the set of pulses; and
determining an average of the drift estimates,
wherein the estimated residual drift comprises the determined average of the drift estimates.
14. The method of claim 13 , wherein the average of the drift estimates comprises a mean of the drift estimates.
15. The method of claim 11 , wherein:
the generation of the drift compensated clock signal is based on a drift estimate provided by a drift compensation algorithm; and
the estimating of the residual drift is based on the drift estimate.
16. The method of claim 15 , further comprising generating an accumulated drift count value based on an estimate of accumulated drift over time, wherein the estimating of the residual drift is further based on the accumulated drift count value.
17. The method of claim 16 , further comprising:
maintaining a record of the accumulated drift count value if pulse acquisition for ranging is commenced;
resetting the accumulated drift count value if the pulse acquisition for ranging is commenced, wherein the estimating of the residual drift uses the accumulated drift count value after the resetting; and
using the maintained record upon completion of the pulse acquisition for ranging to identify a leading edge associated with the acquired ranging pulses.
18. An apparatus for leading edge detection, comprising:
a receiver configured to receive a signal, and further configured to sample the received signal to generate samples, wherein the signal comprises a multipath spread pulse including a plurality of lobes;
a drift compensator configured to generate a drift compensated signal based on the samples;
a signal reconstructor configured to reconstruct the received signal based on the drift compensated signal; and
a leading edge identifier configured to identify a leading edge associated with the received signal based on the reconstructed signal, wherein the leading edge identifier is configured to identify the leading edge by identifying an earliest received one of the plurality of lobes.
19. The apparatus of claim 18 , further comprising:
a resolution increaser configured to increase resolution of the samples to generate higher resolution samples,
wherein the generation of the drift compensated signal comprises time shifting the higher resolution samples.
20. The apparatus of claim 19 , wherein the time shifting of the higher resolution samples is performed at a timing resolution that is higher than a timing resolution of the sampling.
21. The apparatus of claim 19 , wherein the increasing of the resolution comprises zero insertion.
22. The apparatus of claim 18 , wherein the identification of the leading edge employs an interpolation window having a length that is based on a maximum pulse width associated with the received signal.
23. An apparatus for leading edge detection, comprising:
a receiver configured to receive a signal, and further configured to sample the received signal to generate samples, wherein the received signal comprises a plurality of pulses, and wherein the samples comprise a plurality of sample sets associated with the pulses;
a drift compensator configured to generate a drift compensated signal based on the samples, wherein the generation of the drift compensated signal comprises time shifting at least one of the sample sets; and
a signal reconstructor configured to reconstruct the received signal based on the drift compensated signal, wherein the reconstructing of the received signal comprises summing the sample sets after the time shifting; and
a leading edge identifier configured to identify a leading edge associated with the received signal based on the reconstructed signal.
24. The apparatus of claim 23 , wherein the reconstructing of the received signal further comprises performing a thresholding operation to eliminate any isolated elements from the summation of the sample sets.
25. The apparatus of claim 18 , wherein the reception of the signal comprises:
determining a noise level of a communication channel used for receiving the signal; and
setting a gain used for receiving the signal based on the noise level.
26. The apparatus of claim 18 , wherein the sampling comprise one-bit quantization.
27. The apparatus of claim 19 , wherein:
the identification of the leading edge comprises estimating a time of arrival of the leading edge; and
the apparatus further comprises a distance determiner configured to determine a distance between the apparatus and another apparatus based on the estimated time of arrival.
28. An apparatus for leading edge detection, comprising:
a receiver configured to receive a signal, and further configured to sample the received signal to generate samples, wherein the received signal comprises a set of pulses;
a drift compensator configured to generate a drift compensated signal based on the samples;
a signal reconstructor configured to reconstruct the received signal based on the drift compensated signal;
a leading edge identifier configured to identify a leading edge associated with the received signal based on the reconstructed signal;
a clock generator configured to generate a drift compensated clock signal, wherein the generation of the samples is based on the drift compensated clock signal;
a residual drift estimator configured to estimate a residual drift associated with the set of pulses;
wherein the leading edge identifier is further configured to determine timing of the leading edge; and
wherein the leading edge identifier is further configured to adjust the timing based on the residual drift.
29. The apparatus of claim 28 , wherein:
the generation of the drift compensated clock signal comprises adjusting the drift compensated clock signal for clock drift according to a first timing resolution;
the adjustment of the timing is made according to a second timing resolution that is higher than the first timing resolution; and
the adjustment of the timing according to the second timing resolution compensates for residual drift error associated with at least one clock drift adjustment made according to the first timing resolution.
30. The apparatus of claim 28 , wherein the estimating of the residual drift comprises:
determining a set of drift estimates corresponding to the set of pulses; and
determining an average of the drift estimates,
wherein the estimated residual drift comprises the determined average of the drift estimates.
31. The apparatus of claim 30 , wherein the average of the drift estimates comprises a mean of the drift estimates.
32. The apparatus of claim 28 , wherein:
the generation of the drift compensated clock signal is based on a drift estimate provided by a drift compensation algorithm; and
the estimating of the residual drift is based on the drift estimate.
33. The apparatus of claim 32 , wherein:
the drift compensator is further configured to generate an accumulated drift count value based on an estimate of accumulated drift over time; and
the estimating of the residual drift is further based on the accumulated drift count value.
34. The apparatus of claim 33 , wherein:
the drift compensator is further configured to maintain a record of the accumulated drift count value if pulse acquisition for ranging is commenced;
the drift compensator is further configured to reset the accumulated drift count value if the pulse acquisition for ranging is commenced;
the estimating of the residual drift uses the accumulated drift count value after the resetting; and
the leading edge identifier is further configured to use the maintained record upon completion of the pulse acquisition for ranging to identify a leading edge associated with the acquired ranging pulses.
35. An apparatus for leading edge detection, comprising:
means for receiving a signal, wherein the signal comprises a multipath spread pulse including a plurality of lobes;
means for sampling the received signal to generate samples;
means for generating a drift compensated signal based on the samples;
means for reconstructing the received signal based on the drift compensated signal; and
means for identifying a leading edge associated with the received signal based on the reconstructed signal, wherein the leading edge identifying means comprises means for identifying an earliest received one of the plurality of lobes.
36. The apparatus of claim 35 , further comprising:
means for increasing resolution of the samples to generate higher resolution samples,
wherein the generation of the drift compensated signal comprises time shifting the higher resolution samples.
37. The apparatus of claim 36 , wherein the time shifting of the higher resolution samples is performed at a timing resolution that is higher than a timing resolution of the sampling.
38. The apparatus of claim 36 , wherein the increasing of the resolution comprises zero insertion.
39. The apparatus of claim 35 , wherein the identification of the leading edge employs an interpolation window having a length that is based on a maximum pulse width associated with the received signal.
40. An apparatus for leading edge detection, comprising:
means for receiving a signal, wherein the received signal comprises a plurality of pulses;
means for sampling the received signal to generate samples, wherein the samples comprise a plurality of sample sets associated with the pulses;
means for generating a drift compensated signal based on the samples, wherein the generation of the drift compensated signal comprises time shifting at least one of the sample sets;
means for reconstructing the received signal based on the drift compensated signal, wherein the reconstructing of the received signal comprises summing the sample sets after the time shifting; and
means for identifying a leading edge associated with the received signal based on the reconstructed signal.
41. The apparatus of claim 40 , wherein the reconstructing of the received signal further comprises performing a thresholding operation to eliminate any isolated elements from the summation of the sample sets.
42. The apparatus of claim 35 , wherein the reception of the signal comprises:
determining a noise level of a communication channel used for receiving the signal; and
setting a gain used for receiving the signal based on the noise level.
43. The apparatus of claim 35 , wherein the sampling comprise one-bit quantization.
44. The apparatus of claim 35 , wherein:
the identification of the leading edge comprises estimating a time of arrival of the leading edge; and
the apparatus further comprises means for determining a distance between the apparatus and another apparatus based on the estimated time of arrival.
45. An apparatus for leading edge detection, comprising:
means for receiving a signal, wherein the received signal comprises a set of pulses;
means for sampling the received signal to generate samples;
means for generating a drift compensated signal based on the samples;
means for reconstructing the received signal based on the drift compensated signal;
means for identifying a leading edge associated with the received signal based on the reconstructed signal;
means for generating a drift compensated clock signal, wherein the generation of the samples is based on the drift compensated clock signal;
means for estimating a residual drift associated with the set of pulses;
means for determining timing of the leading edge; and
means for adjusting the timing based on the residual drift.
46. The apparatus of claim 45 , wherein:
the generation of the drift compensated clock signal comprises adjusting the drift compensated clock signal for clock drift according to a first timing resolution;
the adjustment of the timing is made according to a second timing resolution that is higher than the first timing resolution; and
the adjustment of the timing according to the second timing resolution compensates for residual drift error associated with at least one clock drift adjustment made according to the first timing resolution.
47. The apparatus of claim 45 , wherein the estimating of the residual drift comprises:
determining a set of drift estimates corresponding to the set of pulses; and
determining an average of the drift estimates,
wherein the estimated residual drift comprises the determined average of the drift estimates.
48. The apparatus of claim 47 , wherein the average of the drift estimates comprises a mean of the drift estimates.
49. The apparatus of claim 45 , wherein:
the generation of the drift compensated clock signal is based on a drift estimate provided by a drift compensation algorithm; and
the estimating of the residual drift is based on the drift estimate.
50. The apparatus of claim 49 , further comprising means for generating an accumulated drift count value based on an estimate of accumulated drift over time, wherein the estimating of the residual drift is further based on the accumulated drift count value.
51. The apparatus of claim 50 , further comprising:
means for maintaining a record of the accumulated drift count value if pulse acquisition for ranging is commenced;
means for resetting the accumulated drift count value if the pulse acquisition for ranging is commenced, wherein the estimating of the residual drift uses the accumulated drift count value after the resetting; and
means for using the maintained record upon completion of the pulse acquisition for ranging to identify a leading edge associated with the acquired ranging pulses.
52. A computer-program product for leading edge detection, comprising:
a non-transitory computer-readable medium embedded with the computer-program product that includes codes executable by an apparatus for:
receiving a signal, wherein the received signal comprises a plurality of pulses;
sampling the received signal to generate samples, wherein the samples comprise a plurality of sample sets associated with the pulses;
generating a drift compensated signal based on the samples, wherein the generation of the drift compensated signal comprises time shifting at least one of the sample sets;
reconstructing the received signal based on the drift compensated signal, wherein the reconstructing of the received signal comprises summing the sample sets after the time shifting; and
identifying a leading edge associated with the received signal based on the reconstructed signal.
53. A headset, comprising:
a receiver configured to receive a signal, and further configured to sample the received signal to generate samples, wherein the received signal comprises a plurality of pulses, and wherein the samples comprise a plurality of sample sets associated with the pulses;
a drift compensator configured to generate a drift compensated signal based on the samples, wherein the generation of the drift compensated signal comprises time shifting at least one of the sample sets;
a signal reconstructor configured to reconstruct the received signal based on the drift compensated signal, wherein the reconstructing of the received signal comprises summing the sample sets after the time shifting;
a leading edge identifier configured to identify a leading edge associated with the received signal based on the reconstructed signal; and
a transducer configured to provide an audio output as a result of the identification of the leading edge.
54. A watch, comprising:
a receiver configured to receive a signal, and further configured to sample the received signal to generate samples, wherein the received signal comprises a plurality of pulses, and wherein the samples comprise a plurality of sample sets associated with the pulses;
a drift compensator configured to generate a drift compensated signal based on the samples, wherein the generation of the drift compensated signal comprises time shifting at least one of the sample sets;
a signal reconstructor configured to reconstruct the received signal based on the drift compensated signal, wherein the reconstructing of the received signal comprises summing the sample sets after the time shifting;
a leading edge identifier configured to identify a leading edge associated with the received signal based on the reconstructed signal; and
a user interface configured to provide an indication as a result of the identification of the leading edge.
55. A sensing device, comprising:
a receiver configured to receive a signal, and further configured to sample the received signal to generate samples, wherein the received signal comprises a plurality of pulses, and wherein the samples comprise a plurality of sample sets associated with the pulses;
a drift compensator configured to generate a drift compensated signal based on the samples, wherein the generation of the drift compensated signal comprises time shifting at least one of the sample sets;
a signal reconstructor configured to reconstruct the received signal based on the drift compensated signal, wherein the reconstructing of the received signal comprises summing the sample sets after the time shifting;
a leading edge identifier configured to identify a leading edge associated with the received signal based on the reconstructed signal; and
a sensor configured to provide data for transmission as a result of the identification of the leading edge.