Optical Pilot Tone Demodulation via DC Blocking and Bias Processing
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Solution Overview
Problem
In optical communication networks, particularly in 5G front-haul applications, the large change range of average power in carrier signals poses a challenge for demodulating low-frequency optical pilot tone signals, leading to incorrect restoration of OAM data due to the dynamic range of the direct current component being too large for post-stage amplification to adapt.
Innovation Solution
A signal demodulation method and apparatus that involves acquiring a signal to be demodulated, performing direct current blocking and bias processing to obtain a processed signal, and comparing this signal with a preset decision signal to obtain a demodulation signal. This approach avoids the dynamic changes of the direct current component caused by average power changes of the carrier signal, allowing for correct demodulation without introducing a negative pressure source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If low-pass filtering is performed on the electric signal detected by the optical power detector, then the optical pilot tone signals can be extracted, but the large dynamic range of the direct current component makes post-stage amplification difficult to adapt
Solution Approach 1:
The patent applies preliminary action by performing direct current blocking processing before the amplification stage. The low-pass filter output is fed into a direct current blocking circuit that removes the large dynamic range direct current component beforehand, allowing the subsequent amplification circuit to operate within its adaptive range without being overwhelmed by large DC variations.
Solution Approach 2:
The patent segments the signal processing into distinct functional stages: first low-pass filtering to extract the pilot tone, then direct current blocking to remove the problematic DC component, and finally amplification. This segmentation allows each stage to be optimized independently, with the amplification stage only handling the AC signal component.
2Adaptability or versatility
If the average power of carrier signals varies within a large range, then the system can handle different power levels, but the direct current component dynamic range becomes too large for correct signal restoration
Solution Approach 1:
The patent extracts and removes the problematic direct current component from the signal path using a dedicated direct current blocking circuit. By taking out the DC component that causes the reliability issue, the system can maintain high adaptability to different carrier power levels while ensuring correct signal restoration through the remaining AC component.
3Reliability
If direct current blocking processing is performed on the modulation signal, then dynamic changes of direct current component can be avoided, but additional processing stages are required
Solution Approach 1:
The patent merges the direct current blocking function with the existing low-pass filtering stage by cascading them in sequence. The output of the low-pass filter directly feeds into the direct current blocking circuit, which then feeds into the amplification stage. This integrated approach achieves reliable demodulation without adding excessive complexity, as each stage builds naturally on the previous one.
Data Source
AI summary
Disclosed are a signal demodulation method and apparatus, a computer storage medium and a device. The method comprises: acquiring a signal to be demodulated; performing direct current blocking and bias processing on the signal to obtain a processed signal; comparing the processed signal with a preset decision signal, and obtaining a demodulation signal according to a comparison result. Thus, direct current blocking processing on a modulation signal can avoid dynamic changes of DC components caused by average power changes of carrier signals, avoiding wrongly demodulating the modulation signal. Bias processing after the direct current blocking on the modulation signal can further realize an AC signal decision without introducing a negative pressure source. A real-time decision on the processed signal via the preset decision signal can dynamically adapt the average power of carrier signals, thereby ensuring to correctly demodulate the modulation signal and improving the accuracy of demodulation results.