initial (mach–zehnder) configuration for a single-channel setup
DESCRIPTION
Wavelength Division Multiplexing (WDM) Laser Vibrometer Signal Conditioning and Processing Fritz Bekkadal CEO Gersemia. Initial (Mach–Zehnder) configuration for a single-channel setup. Demodulation and signal conditioning. Coherent homodyne approach. Quadrature demodulator. - PowerPoint PPT PresentationTRANSCRIPT
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Wavelength Division Multiplexing (WDM) Laser Vibrometer
Signal Conditioning and Processing
Fritz BekkadalCEO
Gersemia
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Initial (Mach–Zehnder) configuration for a single-channel setup
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Demodulation and signal conditioning
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To DSP/PC Demodulator
Baseband conditioning
and ADC
Driver (fB)
Φ
Coherent homodyne approach
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Quadrature demodulator
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Baseband conditioning and ADC
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• The gain adjustments of the I and Q channel amplifiers should be coupled, and preferably be performed electronically. • Initial estimations indicate a gain in the order of 10-20 dB.
fS
A D
Decimation
Analog anti-aliasing LP filter
Amplifier (with adjustable gain)
Digital LP filter
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ADC Front-end circuit
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ADC Front-end design
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BW ≥ 10 MHz
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ADC
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Signal-to-Noise Ratio (SNR)
As a ’rule-of-thumb’: at least an 8 bit ADC is required
…but due to the ADC Dynamic Range (DR) requirements at least a 12 bit ADC is recommended !
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11 1
A Q
A Q
SSNR
N NSNR SNR
10Q ASNR SNR
6QSNR dB b
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ADC Dynamic Range (DR)
DRQ > 60 dB is jugded a minimum with signal compression?
at least a 12 bit ADC is required
Signal compression: Large DC and reflections in the collimator’s vicinity to be
suppressed?
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6( 1)QDR dB b
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Example of ADC saturation
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