Smoothing filter for irregular update intervals
First Claim
Patent Images
1. A system implemented in at least one of a memory or a processing device, comprising:
- a dynamically windowed filter configured to be coupled to a radio receiving a current sample signal associated with a current sample signal strength value;
the dynamically windowed filter is configured to calculate a weighted input signal strength value from the current sample signal strength value;
the dynamically windowed filter is configured to calculate a decayed previous filter output value from a previous output value;
the dynamically windowed filter is configured to add the decayed previous filter output value to the weighted input signal strength value to define a filter output.
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Abstract
A technique for determining a received signal strength from multiple messages filters noise from the received signal to provide an accurate signal strength value. Advantageously, the more accurate output signal strength value can be used to identify movement of a station as well as estimate locations and direction of movement.
586 Citations
20 Claims
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1. A system implemented in at least one of a memory or a processing device, comprising:
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a dynamically windowed filter configured to be coupled to a radio receiving a current sample signal associated with a current sample signal strength value; the dynamically windowed filter is configured to calculate a weighted input signal strength value from the current sample signal strength value; the dynamically windowed filter is configured to calculate a decayed previous filter output value from a previous output value; the dynamically windowed filter is configured to add the decayed previous filter output value to the weighted input signal strength value to define a filter output. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method, comprising:
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receiving a previous output signal strength value, a current signal strength value, and a time elapsed value; decaying the previous output signal strength value with (1) a first function of the time elapsed value and (2) a dynamic time window, to obtain a decayed previous output signal strength value; weighting the current signal strength value with (1) a second function of the time elapsed value and (2) the dynamic time window, to obtain a weighted current signal strength value; adding the decayed previous output signal strength value to the weighted current signal strength value to find a current output signal strength value. - View Dependent Claims (10, 11, 12, 13)
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14. A non-transitory processor-readable medium storing code representing instructions to be executed by a processor, the code comprising code to cause a processor to:
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define a weighted input signal strength value based on a current sample signal strength value; define a decayed previous filter output value based on a previous filter output value; combine the decayed previous filter output value and the weighted input signal strength value to obtain a filter output. - View Dependent Claims (15, 16, 17, 18, 19)
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20. An apparatus, comprising:
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a dynamic window filter configured to receive (1) a current signal strength value, (2) a previous output signal strength value, (3) a dynamic time window value, and (4) a time elapsed value, the dynamic window filter configured to define a decayed previous output signal strength value based on the previous output signal strength, a first function of the time elapsed value, and the dynamic time window value, the dynamic window filter configured to define a weighted current signal strength value based on the current signal strength value, a second function of the time elapsed value, and the dynamic time window value, the dynamic window filter configured to define a current output signal strength value based on the decayed previous output signal strength value and the weighted current signal strength value.
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Specification