Communication Receiver False Preamble Detection Reduction
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Solution Overview
Problem
In electronic systems, receivers often experience false packet detection due to additive white Gaussian noise, which can mimic the characteristics of a preamble signal, leading to incorrect alignment of clock and data recovery systems.
Innovation Solution
An apparatus with a signal detection circuit that includes a counter to determine the time interval between edge signals, a clock circuit to produce aligned clock signal pulses, and phase matching circuitry to detect a packet preamble, along with an interrupt circuit to manage false detections by resetting the system when a sync signal is not detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the receiver uses a CDR circuit to detect preamble signals in noisy environments, then clock and data recovery can be achieved, but false packet detection occurs due to noise mimicking preamble characteristics
Solution Approach 1:
The detection process is divided into multiple independent stages: edge detection, time interval measurement, threshold comparison, and pattern matching. Each stage processes specific features separately, allowing the system to accumulate evidence for valid preamble detection while rejecting noise through progressive filtering criteria.
Solution Approach 2:
The system transforms the detection problem from direct signal pattern matching to a parameter-based approach by measuring time intervals between edge signals. This parameter transformation converts the detection task into comparing measured intervals against expected preamble characteristics, making the detection more robust to noise variations.
2Productivity
If the receiver continuously monitors for packet data, then it can quickly detect valid packets, but it consumes more time processing false alarms from noise
Solution Approach 1:
The system performs preliminary edge detection and time interval measurement before committing to full packet processing. By pre-processing and validating edge signal characteristics against expected preamble parameters, the system eliminates false detections early, preventing wasted processing time on invalid packets while maintaining rapid response to valid packets.
3Measurement precision
If the receiver uses oversampled DPLL to detect preamble edges, then clock alignment can be achieved, but the system becomes more sensitive to noise edges
Solution Approach 1:
The system uses feedback through threshold comparison of measured time intervals against expected preamble characteristics. By continuously monitoring whether measured intervals match expected values and adjusting detection decisions accordingly, the system maintains high precision for valid edge detection while using the threshold feedback mechanism to reject noise edges that do not conform to expected patterns.
Data Source
Figure 1A~1B
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AI summary
An apparatus comprising: a signal detection circuit determine a count reached by a counter between successive detected edge signals and to provide an indication of whether successive detected edge signals are separated from each other by at least a prescribed time interval; a clock circuit that produces clock signal pulses in response to a provided indication of an occurrence of a succession of detected edge signals each separated from a previous edge signal of the succession by at least the prescribed time interval; phase matching circuitry configured to align the produced clock signal pulses with detected edge signals; and a pattern matching circuit that that samples a sequence of detected edge signals aligned with the produced clock signal pulses to detect a data packet.