Transceiver Delay Calibration for Precise Signal-Path Timing
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Solution Overview
Problem
Existing communication systems face challenges in achieving precise time synchronization and accurate ranging due to variable propagation delays through transmit and receive signal paths, which are influenced by factors such as operating conditions, temperature, and mechanical position, leading to inaccuracies in timestamping and location-based tracking.
Innovation Solution
The system employs a programmable logic device, such as an FPGA, to calibrate the transmit and receive signal paths by determining precise delays using calibration sequence signals, accounting for both integer and fractional delays, enabling accurate timestamp adjustments and time-of-flight calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If variable propagation delays through transmit and receive optical, interconnect and electronic circuits are present, then communication systems can operate under different operating conditions, but time synchronization accuracy and ranging accuracy deteriorate
Solution Approach 1:
The system performs preliminary calibration by sending calibration signals through the transmit and receive signal paths to measure and store delay values before actual communication operations. This preliminary measurement allows the system to compensate for variable propagation delays during normal operation, resolving the contradiction between adaptability to different conditions and time synchronization accuracy.
Solution Approach 2:
The system implements feedback mechanisms where measured delay values from calibration signals are fed back into the timestamping process. The timestamping circuitry uses these feedback delay measurements to adjust and correct time measurements, ensuring accurate time synchronization even when propagation delays vary due to different operating conditions.
2Measurement precision
If higher clock frequencies are used to achieve picosecond-level accuracy, then time synchronization precision improves, but device complexity and manufacturing difficulty worsen
Solution Approach 1:
The patent introduces calibration signals as intermediaries that travel through the signal paths at lower frequencies to measure delays. These calibration signals act as mediators between the clock domain and the timestamping domain, allowing precise delay measurement without requiring the main communication signals to operate at extremely high frequencies. The calibration process separates the high-precision measurement function from the high-speed data transmission function.
Data Source
AI summary
Systems, methods, and circuitry for determining a delay through a modem of a transceiver are provided. An integrated circuit system may include a transmit signal path, delay calibration circuitry, and a phase detector. The delay calibration circuitry may allow determination of a delay through a transmit signal path between a calibration sequence signal source and an output of the transmit signal path. The transmit signal path may include a number of processing stages having a possible delay variation under different conditions. The phase detector may determine a fractional baud rate difference between the calibration sequence signal source and a signal representative of the output of the transmit signal path