Adaptive Receiver Gain for BLE Indoor Positioning Accuracy
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Solution Overview
Problem
Fluctuations in received signal levels during direction-finding in wireless positioning systems cause saturation and underrun issues in RF stages, impacting the accuracy of phase and amplitude estimation in Bluetooth Low Energy (BLE) devices.
Innovation Solution
The implementation of an interrogation device with adjustable receiver stages and digital processing circuitry that adapts gains based on received signal levels and phases, using Automatic Gain Control (AGC) logic to minimize distortion and accurately estimate the position of wireless devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If antenna switching is performed during direction-finding field reception, then position estimation capability is enabled, but signal level fluctuations cause saturation and underrun in receiver stages
Solution Approach 1:
The receiver stages employ adjustable gains that can be dynamically adapted during reception of the direction-finding field. The digital processing circuitry monitors signal levels and modifies the gains of receiver stages in real-time to prevent saturation when signal levels are high and to avoid underrun when signal levels are low, thereby maintaining reliable signal reception while enabling position estimation through antenna switching
Solution Approach 2:
The system implements a feedback mechanism where the digital processing circuitry continuously monitors the received signal levels during direction-finding field reception and uses this information to adaptively adjust the gains of receiver stages. This feedback loop ensures that the receiver maintains optimal operating conditions despite signal level fluctuations caused by antenna switching, resolving the contradiction between position estimation capability and signal reception reliability
2Measurement precision
If receiver gains are increased to avoid underrun, then signal detection sensitivity improves, but signal saturation occurs at receiver stages
Solution Approach 1:
The receiver stages use dynamically adjustable gains controlled by digital processing circuitry that monitors signal levels in real-time. When signal levels are low, the gains are increased to improve detection sensitivity; when signal levels are high, the gains are decreased to prevent saturation. This dynamic adjustment resolves the contradiction between sensitivity and saturation
Solution Approach 2:
The system changes the gain parameter of receiver stages adaptively based on the actual signal conditions. The digital processing circuitry modifies the gain parameter in response to detected signal levels, allowing the receiver to operate optimally across varying signal conditions without suffering from either underrun or saturation
3Object-affected harmful factors
If receiver gains are decreased to avoid saturation, then signal saturation is reduced, but signal underrun occurs at ADC input
Solution Approach 1:
The adjustable gains in receiver stages are dynamically controlled based on real-time signal level monitoring. When saturation is detected, the gains are decreased to prevent distortion; when signal levels drop, the gains are increased to maintain detection accuracy and prevent underrun at the ADC input
Solution Approach 2:
The digital processing circuitry implements feedback control by monitoring signal levels and adjusting receiver stage gains accordingly. This feedback mechanism ensures that gains are optimized to prevent both saturation and underrun, maintaining signal detection accuracy across varying reception conditions
Data Source
AI summary
An interrogation device, for locating a wireless device, includes a receiver and digital processing circuitry. The receiver includes one or more receiver stages having adjustable gains, and is configured to receive from the wireless device a signal that carries a packet including a direction-finding field, wherein, during reception of the direction-finding field, multiple different temporal sections of the received signal traverse different wireless channels due to switching among different antennas in the interrogation device or in the wireless device and thus have multiple different received-signal levels. The digital processing circuitry is configured, based on the multiple received temporal sections of the signal during reception of the direction-finding field, to (i) adapt the adjustable gains of the receiver stages and (ii) estimate a position of the wireless device.