Compact Frequency Reference

KOFREF

Stable and accurate frequency references are crucial for a wide range of applications, particularly in the field of atomic quantum sensors. The Compact Frequency Reference (KOFREF) project focuses on the mobile generation of an agile and long-term stable frequency reference using GNSS referencing. It aims to address the limitations of existing passive masers, cesium, and rubidium clocks by developing a GNSS-based frequency transmission system with unprecedented stability.

The project's objective is to develop a GNSS-based frequency transmission system that offers exceptional stability. This involves mitigating the dominant error sources associated with satellite navigation systems, such as satellite clock errors, orbit prediction errors, biases in satellite electronics, and the impact of ionosphere and troposphere on signal propagation. By utilizing a network of GNSS reference stations, KOFREF aims to map and correct for ionospheric and tropospheric effects in real-time, providing users with precise and accurate frequency corrections.

Existing GNSS reference station networks primarily focus on positioning and do not require absolute satellite clock corrections. The project member Geo++ proposes the integration of at least one GNSS reference station with a stable and accurate frequency source, enabling the transfer of stability and absolute frequency from the reference source to the satellite clocks. The system then uses this source to regulate the frequency of a local oscillator to match the corrected frequency.

To test this frequency, in cooperation with the Leibniz University Hannover we aim to develop compact electronic modules for mobile quantum sensors. These modules will include a phase-locked, low-phase-noise frequency reference in the radiofrequency and microwave range implemented in a FPGA-controlled hardware. Compact electronic modules for controlling and reading atomic sensors, along with operational software using the OpenSource SINARA Hardware, will be developed. The frequency reference module will be tested on a quantum sensor to generate composite pulses with reduced sensitivity to external noise sources.

Through the development of the KOFREF project, a new generation of highly stable and compact frequency references for atomic quantum sensors is anticipated. The integration of GNSS referencing and advanced electronic modules will significantly enhance the performance and reliability of these sensors, opening up new possibilities for precision measurement applications.

Project participants

  • German Aerospace Center, Institute for Satellite Geodesy and Inertial Sensing
  • Geo++ GmbH
  • Leibniz University Hannover, Insitute of Quantum Optics

Funded by

Departments

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Kontakt

apl. Prof. Carsten Klempt

Commissary Head Optical Frequency Metrology
German Aerospace Center (DLR)
Institute for Satellite Geodesy and Inertial Sensing
Optical Frequency Metrology
Callinstrasse 30b, 30167 Hannover
Germany