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New Cable Delay Measurement System for VGOS Stations
Pablo García-Carreño1, Javier González-García1, María Patino-Esteban1
1Yebes Observatory, Centro de Desarrollos Tecnológicos, Instituto Geográfico Nacional, Ministerio de Transportes, Movilidad y Agenda Urbana, Cerro de la Palera s.n., 19141 Yebes, Spain.
Sensors (Basel, Switzerland)
|March 26, 2022
Summary
A new cable delay measurement system (CDMS) enhances Very Long Baseline Interferometry Global Observing System (VGOS) by accurately measuring cable length changes. This advanced system achieves sub-picosecond noise levels, improving geodetic measurements.
Area of Science:
- Geophysics and Radio Astronomy
- Instrument Development for Geodetic Measurements
Background:
- Very Long Baseline Interferometry Global Observing System (VGOS) stations require precise measurements of cable delays.
- Environmental factors like temperature and telescope movement affect coaxial cable length and signal propagation.
- Previous measurement systems had limitations in accuracy, noise, and automation.
Purpose of the Study:
- To introduce and validate a new Cable Delay Measurement System (CDMS) for VGOS stations.
- To improve the accuracy and reliability of phase/delay measurements in coaxial cables.
- To develop a system with reduced digital noise and enhanced automation for calibration.
Main Methods:
- Measuring the phase difference between a stable 5 MHz reference signal and the signal received through a coaxial cable.
- Utilizing a remotely controlled automatic calibration subsystem.
- Testing the system's performance in laboratory and operational radio telescope environments.
Main Results:
- The CDMS achieves an RMS noise of less than 0.5 picoseconds, exceeding VGOS requirements.
- The system accurately detects cable length variations due to temperature and flexures.
- Performance metrics including noise, accuracy, hysteresis, and stability were evaluated.
Conclusions:
- The new CDMS offers superior performance compared to previous systems.
- The system's accuracy and automation significantly benefit VGOS operations.
- The CDMS is being deployed in multiple VGOS stations globally, including RAEGE, NMA, and FGI.
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