Atmospheric transmissometer using a modulated optical source
First Claim
1. A method comprising the steps of:
- detecting a modulated optical signal from an atmospheric propagation channel, wherein the modulated optical signal comprises an optical signal from an optical source modulated with a periodic signal at a modulation frequency greater than the bandwidth of turbulence within the atmospheric propagation channel;
converting the detected modulated optical signal into a digitized electrical signal;
determining the power spectral density (PSD) of the digitized electrical signal;
extracting, from the PSD, the magnitude of the peak component at the modulation frequency f0, referred to as Satmos(f0); and
determining the effective optical depth τ
eff of the atmospheric propagation channel using the magnitude of the peak component at the modulation frequency.
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Abstract
A system and method involve detecting a modulated optical signal from an atmospheric propagation channel, wherein the modulated optical signal comprises an optical signal from an optical source modulated with a periodic signal at a modulation frequency greater than the bandwidth of the turbulence within the atmospheric propagation channel, and converting the detected modulated optical signal into a digitized electrical signal. The method also includes determining the root mean square signal power of an AC component of the digitized electrical signal at the modulation frequency. The method further includes determining the power spectral density of the digitized electrical signal, determining the magnitude of the peak component at the modulation frequency, and determining the effective optical depth of the atmospheric propagation channel using the magnitude of the peak component at the modulation frequency.
23 Citations
12 Claims
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1. A method comprising the steps of:
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detecting a modulated optical signal from an atmospheric propagation channel, wherein the modulated optical signal comprises an optical signal from an optical source modulated with a periodic signal at a modulation frequency greater than the bandwidth of turbulence within the atmospheric propagation channel; converting the detected modulated optical signal into a digitized electrical signal; determining the power spectral density (PSD) of the digitized electrical signal; extracting, from the PSD, the magnitude of the peak component at the modulation frequency f0, referred to as Satmos(f0); and determining the effective optical depth τ
eff of the atmospheric propagation channel using the magnitude of the peak component at the modulation frequency. - View Dependent Claims (2, 3, 4)
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5. A method comprising the steps of:
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detecting a modulated optical signal from an atmospheric propagation channel, wherein the modulated optical signal comprises an optical signal from an optical source modulated with a periodic signal at a modulation frequency greater than the bandwidth of turbulence within the atmospheric propagation channel; converting the detected modulated optical signal into a digitized electrical signal; determining the root mean square (RMS) signal power of an AC component of the digitized electrical signal at the modulation frequency; using the determined RMS signal power to determine a received RMS signal power of the detected modulated optical signal at the modulation frequency; and determining the transmission of the atmospheric propagation channel by calculating a ratio between the received RMS signal power of the detected modulated optical signal and the expected RMS signal power of the detected modulated optical signal. - View Dependent Claims (6)
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7. A system comprising:
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a modulator configured to modulate an optical signal from an optical source with a periodic signal at a modulation frequency greater than the bandwidth of turbulence within an atmospheric propagation channel; a transmitter configured to propagate the modulated optical signal into the atmospheric propagation channel; an optical detector configured to detect the propagated modulated optical signal from the atmospheric propagation channel; an AC coupled detector, operatively connected to the optical detector, configured to convert the propagated modulated optical signal into an electrical voltage; and an analog-to-digital converter (ADC), operatively connected to the AC coupled detector, configured to digitize the electrical voltage; and an optical depth processing subsystem, operatively connected to the ADC, comprising averaging and signal conditioning circuitry, PSD processing circuitry operatively connected to the averaging and signal conditioning circuitry, and a bandpass filter operatively connected to the PSD processing circuitry. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification