Transmitter Gain Correction Using Fast Envelope Cross-Correlation
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Solution Overview
Problem
Existing power control methods in communication terminals are inaccurate due to variations in temperature, transmit frequency, and supply voltage, leading to inefficiencies in transmitter gain and failure to meet communication standards, especially at high power levels and in non-linear regions.
Innovation Solution
A method that determines the actual gain between measurement points in a communication terminal's transmission chain by computing the cross-correlation of signal envelopes, allowing for real-time gain correction and accurate output power adjustment without relying on pre-calibration, thereby compensating for gain variations and ensuring high accuracy in power control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If pre-calibration methods are used for power control, then device complexity is reduced, but manufacturing precision deteriorates due to gain variations from temperature, frequency, and voltage changes
Solution Approach 1:
The system performs preliminary envelope detection and cross-correlation computation to determine actual gain values before power adjustment. By pre-computing the gain relationship between first and second measurement points using cross-correlation of signal envelopes, the system establishes an accurate gain profile that compensates for temperature, frequency, and voltage variations before they affect power control accuracy.
Solution Approach 2:
The system continuously monitors signal envelopes at two different measurement points and uses cross-correlation to compute actual gain in real-time. This feedback mechanism allows the power control algorithm to adjust transmitter gain dynamically based on measured gain variations, compensating for environmental factors and maintaining accurate power control despite changes in operating conditions.
2Manufacturing precision
If extensive calibration is performed to improve power control accuracy, then manufacturing precision is improved, but productivity deteriorates due to increased calibration time and cost
Solution Approach 1:
The system performs self-calibration by automatically computing actual gain values through cross-correlation of signal envelopes measured at two points in the transmission chain. This self-service approach eliminates the need for manual, time-consuming calibration procedures while maintaining high power control accuracy, as the device calibrates itself during normal operation using its own transmitted signals.
Solution Approach 2:
The system changes the approach from static pre-calibration to dynamic parameter measurement by computing actual gain based on signal envelope cross-correlation. This parameter-based method allows the system to adapt to changing operating conditions (temperature, frequency, voltage) without requiring re-calibration, thereby maintaining accuracy while improving production efficiency.
3Speed
If fast envelope detection is implemented, then speed of power control is improved, but device complexity increases due to additional measurement and computation requirements
Solution Approach 1:
The system uses the same signal envelope detection and cross-correlation computation for multiple purposes: determining actual gain for power control, monitoring transmission chain performance, and characterizing signal properties. This multi-functional approach achieves fast power control response without proportionally increasing device complexity, as the same hardware and algorithms serve multiple functions.
Solution Approach 2:
The signal envelope acts as an intermediary between the transmitted signal and the power control decision. By detecting envelopes at two measurement points and computing their cross-correlation, the system obtains actual gain information without directly measuring power, simplifying the measurement process while enabling fast response. The envelope detection serves as a mediator that translates complex signal variations into usable gain information.
Data Source
AI summary
A method for controlling output signal power in a communication terminal includes determining envelopes of a communication signal to be transmitted by the communication terminal at respective first and second measurement points along a transmission chain in a transmitter of the terminal. A cross-correlation is computed between the envelopes determined at the first and second measurement points. An actual gain between the first and second measurement points is computed using the cross-correlation. An output power of the communication signal is adjusted by setting a gain of the transmitter responsively to the actual gain.