Digital Receiver Noise Characterization Without Calibration
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Solution Overview
Problem
Existing wireless communication systems face challenges in rapidly and accurately characterizing channel noise and interference without requiring precise and frequent calibration of test apparatus, which is necessary for selecting optimal communication channels and transmission power to maintain communication performance.
Innovation Solution
A digital wireless receiver system that uses a digital test signal generator to produce a known modulated signal, which is adjusted in amplitude and combined with digitized noise and interference to determine the signal-to-noise interference ratio (SNIR) using correlation statistics and message error rates, eliminating the need for calibration of test apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an analog loopback path including a coupler and mixer is provided in the receiver hardware to characterize noise and interference, then the characterization accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent replaces the mechanical/analog loopback path (including coupler and mixer hardware) with a digital signal processing approach. The digital receiver generates a digital test signal that is combined with digitized noise and interference samples in the digital domain, eliminating the need for complex analog hardware components while maintaining measurement accuracy.
Solution Approach 2:
The patent introduces a digital test signal as an intermediary element that mediates between the digitized noise/interference and the performance evaluation. This digital test signal serves as a reference that allows accurate characterization without requiring direct analog loopback paths.
2Measurement precision
If an analog test signal is introduced into the wireless receiver together with received interference to assess channel impairment, then the measurement precision is improved, but the ease of operation deteriorates due to precise and frequent calibration requirements
Solution Approach 1:
The patent replaces the analog test signal generation and injection system with a digital test signal generated entirely within the digital receiver. This digital approach eliminates the calibration requirements associated with analog signal generators and injection paths, as digital signal levels and characteristics are inherently stable and precisely controllable.
Solution Approach 2:
The digital receiver performs self-characterization by generating its own digital test signal internally and combining it with received noise and interference samples. This self-service approach eliminates the need for external calibration equipment and procedures, making the system easier to operate while maintaining measurement precision.
3Measurement precision
If the analog test signal amplitude is adjusted to be approximately equal to the received interference amplitude, then the measurement precision is improved, but the time required for calibration and adjustment increases
Solution Approach 1:
The patent replaces the manual or iterative adjustment process for matching analog test signal amplitude with digital signal processing. The digital test signal amplitude can be precisely controlled and adjusted through digital gain factors without requiring time-consuming calibration procedures, as digital signal levels are inherently stable and easily adjustable through software control.
Solution Approach 2:
The digital test signal is generated with predetermined known characteristics and amplitude relationships before being combined with the received noise and interference. This preliminary preparation of the digital test signal eliminates the need for real-time amplitude matching and calibration during the measurement process, reducing the time required for accurate characterization.
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AI summary
A wireless receiver and method of wireless communication determines levels of noise, including interference, in communication channels without need of calibration. A digital test signal is digitally added to digitized noise, and a signal- to-noise-and-interference (SNIR) value is determined from a resulting bit error rate and/or message error rate. The level of noise is then determined from the SNIR. The amplitude of the digital test signal is adjusted to cause the SNIR to be sensitive to the noise level, which can require an SNIR between 1 dB and 10 dB. The system can include a digital test signal generator, or the digital test signal can be stored in a memory. The system can further include a channelizer, demodulator, data correlator, decryptor, and message assembler. Noise and interference level determinations can be used to select an optimal communication channel, and to adjust a transmission power and/or rate to suitable values.