Measuring with Known Frequencies via Internal Reference |
When the frequency of the signal under test is known, you can configure your lock-in amplifier to Internal Reference Mode and manually input the target frequency. While this approach allows for immediate measurement, it introduces a specific technical challenge: phase drifting.
The Challenge: Why Does the Phase Drift in Internal Mode? |
Because the phase is not explicitly locked to an external hardware source, the signal under test and the internal reference clock cannot achieve absolute synchronization in frequency and phase. Even a microscopic divergence over time will cause the measured phase to constantly shift or drift, complicating long-term stability in precision testing.
The Solution: Tracking Unknown or Unlocked Frequencies |
If the exact signal frequency is unknown, or if you need to eliminate phase discrepancies, manual internal mode is insufficient. Instead, advanced instrument techniques should be deployed:
Spectrum Analysis Method: Scan the frequency spectrum first to identify the exact peak frequency of the signal under test.
Phase-Locked Loop (PLL) Frequency Sweep: Utilize a hardware or digital PLL to perform automatic frequency sweeping and tracking. This dynamically locks the reference frequency and phase to the incoming signal, stabilizing the phase readout.
Related products: |
Lock-In Amplifiers: Principle, Applications & Products | Saluki Technology
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