Beats arising from the interference among waves with different frequencies have emerged as a powerful tool for precision measurements. In a $lin\left|\right|lin$ coherent-population-trapping (CPT) clock, such beats can be induced by a double-$\mathrm{\Lambda }$ CPT transition that shares a common excited state. Here we employ CPT-Ramsey interferometry to experimentally explore the underlying beating dynamics in such a double-$\mathrm{\Lambda }$ CPT transition. The observed beating results from the differential Zeeman shifts between the two $\mathrm{\Lambda }$ subsystems, which are caused by the opposite nuclear spin projections in the involved states. The amplitude of the frequency-domain Ramsey fringes depends strongly on both the magnetic field strength and the Ramsey time, exhibiting clear constructive and destructive interference patterns. This dependence enables the optimization of signal contrast in CPT clocks by tuning the magnetic field and Ramsey time. The overall light shift ${\nu }_{\mathrm{LS}}$ relates to the sum of two initial phases ${\mathrm{\Theta }}_{+}$ for the two $\mathrm{\Lambda }$ structures: ${\nu }_{\mathrm{LS}}=-{\mathrm{\Theta }}_{+}/\left(2\pi T\right)$ for a given Ramsey time $T$. In the vicinity of resonance, this light shift is approximately proportional to the two-photon detuning $\delta$ if $\left|\delta \right|\le$ 4 kHz. Through enabling the precise measurement and effective suppression of light shifts, our approach provides a direct path toward improved stability and accuracy in cold-atom CPT clocks. Our work provides promising application prospects in the field of quantum sensing, such as ultra-weak magnetic field measurement.

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• Atom interferometry
• Atomic, optical & lattice clocks
• Quantum metrology
• Quantum optics