Measurement of air characteristics in the lower atmosphere
First Claim
1. A method for acoustically sounding air over a range that extends away from an acoustic transmitter and receiver, the method comprising the steps of:
- transmitting an acoustic chirp comprising coded pulses having pulse compression waveforms and having a duration of at least 300 ms down-range, using the receiver to detect acoustic inputs and to generate a receiver output that is representative of said inputs, and processing said receiver output to generate signal phase data indicative of air characteristics in the range.
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Accused Products
Abstract
Sodar systems and methods for acoustically sounding air are disclosed in which chirps longer than 300 ms—and preferably with durations of tens of seconds—are used along with matched filter and/or Fourier processing methods to derive phase signals indicative of air characteristics in range. A listen-while-transmit strategy is preferred, the direct signal being removed by subtracting the phase signals from two or more receivers located near the transmitter so as to be in the same noise environment. The resultant differential signals can be related to cross-range wind with range distance. In one example, apparatus (100) is employed comprising a reflector dish (102) over which one central loudspeaker (110) and four microphones (112, 114, 130 and 132) are mounted, the microphones preferably being located on cardinal compass points and having their axes (124, 126) slightly angled with respect to the vertical transmission axis (122).
27 Citations
44 Claims
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1. A method for acoustically sounding air over a range that extends away from an acoustic transmitter and receiver, the method comprising the steps of:
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transmitting an acoustic chirp comprising coded pulses having pulse compression waveforms and having a duration of at least 300 ms down-range, using the receiver to detect acoustic inputs and to generate a receiver output that is representative of said inputs, and processing said receiver output to generate signal phase data indicative of air characteristics in the range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A system for acoustically sounding air over a range that extends away from an acoustic transmitter and receiver:
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a transmitter adapted to transmit an acoustic chirp comprising coded pulses having pulse compression waveforms and having a duration of at least 300 ms down a range that extends away from the transmitter, a receiver located near said transmitter and adapted to detect acoustic signals including echoes of the transmitted chirp returned from down-range and adapted to generate a receiver output that is representative of said received acoustic signals, and a digital signal processor for processing said receiver output to generate signal phase data indicative of air characteristics in the range. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44)
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Specification