NDIR against Metal Oxide Films in CO2 Measurement
NDIR sensors provide definitive CO2 accuracy through direct mid-IR light absorption, while low-cost metal oxide films infer CO2 via prone cross-reactive surface chemistry.
Lock in Amplification
Phase Recovery
Phase-sensitive detection techniques extract weak electrical signals from high-noise environments by synchronizing measurement with a reference frequency. Applying lock in amplification isolates narrow-band sensor signals even when noise amplitudes exceed the target signal by orders of magnitude. This signal processing methodology governs low-level optical and magnetic sensor measurements where ambient noise corrupts unmodulated signals.
The operational boundary requires a stable reference frequency, stopping at unmodulated DC signals or random transient signals that cannot be phase-locked. Demodulation multiplies the input signal by the reference signal, transferring target information to zero frequency for low-pass filtering.
Reference Sync
Internal or external reference signals drive the phase-locked loop to maintain synchronization. Effective lock in amplification requires precise phase alignment between excitation modulation and detection logic. Phase shifts introduced by cables require phase adjustment during calibration.
Filter Bandwidth
Low-pass output filters determine the dynamic response and signal-to-noise ratio of the amplifier system. Narrower filter bandwidths suppress random noise but lengthen signal settling times. Dynamic adjustments optimize response speed against noise rejection.
Signal Extraction
Dual-phase demodulators measure orthogonal signal components to compute amplitude and phase angle simultaneously. Precision hardware eliminates DC offsets and 1/f noise from optical sensor channels. Output data provides high signal clarity for trace detection instruments.