I am studying Satellite Laser Ranging (SLR) and its observation quality. I would like to understand whether observations made at night or during the day have different levels of accuracy and precision. Specifically, I am interested in knowing which time of day is generally considered better for SLR observations and what factors—such as atmospheric conditions, ambient light, or system calibration—affect the data quality. Also, are there operational differences between conducting SLR measurements at night compared to during the day? If anyone is working at SLR stations and has experience with these aspects, your input would be a welcome help and greatly appreciated.
1. Background Light and Signal Detection:
- Daytime Observations: Sunlight increases background noise, making it challenging to detect the faint laser returns from satellites. This elevated noise level can reduce the signal-to-noise ratio (SNR), affecting measurement precision.
- Nighttime Observations: The absence of sunlight results in lower background noise, facilitating clearer detection of laser signals and improving data quality.
2. Atmospheric Conditions:
- Daytime Observations: Solar heating causes atmospheric turbulence, leading to variations in air density. These fluctuations can scatter and distort the laser beam, reducing measurement accuracy.
- Nighttime Observations: The atmosphere tends to be more stable at night, allowing for more consistent laser beam propagation and enhanced measurement precision.
3. Technological Adaptations:Advancements in SLR technology have mitigated some daytime observation challenges. For instance, the use of ultra-high repetition rate lasers (e.g., 100 kHz) and single-photon detectors has enabled effective daytime ranging by improving the SNR and compensating for increased background noise. Studies have demonstrated successful daytime SLR at high repetition rates, achieving millimeter-level accuracy.
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4. Operational Considerations:Daytime SLR requires additional measures, such as narrowband optical filters and precise timing systems, to counteract the effects of sunlight and atmospheric turbulence. These adaptations can increase system complexity and operational costs.
Thank you, Prof. Ruqayah Al-ani , for this information.
Best regards, Ruby
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