RF Receiver Packet Detection Using Analog and Digital GO Circuits
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Solution Overview
Problem
Bluetooth receivers face challenges in accurately detecting RF data packets due to interference from adjacent channel interference (ACI), co-channel interference (CCI), and noise, which complicates signal reception and increases complexity and cost with the use of phase locked loops (PLLs) for symbol timing recovery.
Innovation Solution
An RF receiver system with analog and digital GO circuits that recognize data packets by sensing power and energy, respectively, and employ FIR filters to distinguish packets from noise and ACI, enabling improved gain control and demodulation functions, while an STR circuit cross-correlates preamble samples to decode data packets efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a phase locked loop (PLL) is used for symbol timing recovery, then timing accuracy is improved, but receiver complexity and cost increase
Solution Approach 1:
The patent extracts the essential timing recovery function from the complex PLL system and implements it through a simplified correlator-based approach that uses the known preamble sequence to directly determine symbol timing, eliminating the need for continuous phase tracking loops
Solution Approach 2:
The patent replaces the expensive, continuous-operating PLL with a low-cost, burst-mode correlator that processes timing information only during the preamble period, using simple multiplication and accumulation operations instead of complex feedback control
2Measurement precision
If the RSSI operates continuously to detect data packets, then detection accuracy is improved, but false detection from interference increases
Solution Approach 1:
The patent introduces a correlator as an intermediary between the RSSI and the packet detection logic, using the known preamble sequence as a reference to filter out interference and noise, allowing accurate detection even in the presence of ACI and CCI
Solution Approach 2:
The patent uses the distinctive temporal pattern of the preamble (alternating +1 and -1 bits) as a signature that can be identified through correlation, effectively changing the detection criterion from simple power threshold to pattern recognition that is immune to interference
3Reliability
If a long integration period is used for packet detection, then detection reliability is improved, but response time increases
Solution Approach 1:
The patent performs preliminary correlation processing during the 5-bit preamble period to establish packet presence and timing, allowing the main data reception to begin immediately without requiring extended integration periods for detection
Data Source
AI summary
An RF receiver includes an analog GO circuit that recognizes the presence of a data packet within a received RF signal in the receiver's analog gain control section, and in response produces an analog GO signal, and a digital GO circuit that recognizes the presence of a data packet from the receiver's digital demodulator section, and in response produces a digital GO signal. Gain control functions within the analog gain control section, and digital demodulator functions within the digital demodulator section, are enabled in response to respective analog and digital GO signals. The system is capable of distinguishing a valid data packet from noise, co-channel interference and adjacent panel interference. A symbol timing recovery circuit within the receiver identifies periodic samples of a data packet preamble that most closely match the preamble bits, with the receiver employing a continuation of the identified periodic samples to decode the remainder of the data packet.