Constant-Envelope Composite Signal for Satellite Crosslinks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current satellite crosslink technologies face limitations in achieving high data rates, accurate ranging, and independent power levels for data and ranging signals, while also being vulnerable to jamming threats, with existing systems compromising on data rate and ranging accuracy or signal power independence.
Innovation Solution
A system using binary offset carrier (BOC) modulation and interplex modulation to generate a constant-envelope composite signal, allowing for independent control of data and ranging signal power levels and bandwidths, enabling simultaneous high-data-rate and high-accuracy ranging with jam-resistant operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate operating modes are used for data transmission and ranging, then each function can be optimized independently, but continuous simultaneous data transmission and ranging cannot be achieved
Solution Approach 1:
The patent combines data transmission and ranging functions into a single unified waveform called the constant-envelope composite signal. This merging allows both functions to operate simultaneously in the same time slot, eliminating the need for separate operating modes and enabling continuous dual-function operation.
Solution Approach 2:
The constant-envelope composite signal serves multiple functions simultaneously: it carries data transmission, performs ranging measurements, and maintains constant envelope for efficient power amplification. This multi-functionality resolves the contradiction by making a single signal perform what previously required separate dedicated signals.
2Adaptability or versatility
If linear RF amplification is used to accommodate multiple signals with different power levels, then independent power control is possible, but amplification efficiency decreases
Solution Approach 1:
The patent transforms the signal parameters by combining multiple signals into a constant-envelope composite signal. This parameter transformation allows the use of non-linear power amplifiers (which are highly efficient) while still enabling independent power control of constituent signals through the interplex modulation structure and post-processing at the receiver.
Solution Approach 2:
The constant-envelope composite signal acts as an intermediary that carries multiple independent signals through an efficient non-linear amplifier. The interplex modulation structure serves as the mechanism that embeds multiple signals with different power requirements into this single constant-envelope carrier, allowing efficient amplification while preserving independent power control capability.
3Productivity
If wide bandwidth is allocated for high data rate transmission, then data rate increases, but ranging accuracy deteriorates
Solution Approach 1:
The patent segments the constant-envelope composite signal into distinct spectral components: a wideband component for high-rate data transmission and a narrowband component for precise ranging measurements. This segmentation allows each function to utilize the bandwidth appropriate for its requirements without interfering with the other, resolving the contradiction between data rate and ranging accuracy.
Solution Approach 2:
Different portions of the signal spectrum are assigned different qualities: the wideband portions carry high-rate data requiring large bandwidth, while the narrowband portion carries ranging signals requiring concentrated power and narrow bandwidth for high precision. This local quality assignment allows simultaneous optimization of both data transmission and ranging functions.
4Device complexity
If fixed frequency transmission is used for simple implementation, then system complexity is reduced, but resistance to jamming decreases
Solution Approach 1:
The patent introduces dynamic frequency agility to the constant-envelope composite signal, allowing the signal to hop between different frequency bands. This dynamic behavior provides resistance to narrowband jamming and interference while maintaining relatively simple implementation through the interplex modulation framework, which can accommodate frequency changes without requiring complete system redesign.
Data Source
AI summary
A communication system generates a constant-envelope composite signal containing at least two signals whose power levels, bandwidths, and/or data rates are independently controllable. Binary offset carrier (BOC) modulation is applied to the signals to be combined in the composite signal. The BOC modulated signals are then combined via interplex modulation to form a constant-envelope composite signal in which the constituent signals modulate different offset carriers. For example, real BOC modulation can be used to generate a ranging signal in edge portions of the transmission band of the composite signal, while complex BOC modulation can be used to generate a frequency agile data signal in a center portion of the transmission band. Such a signal can be used for full duplex communications in satellite crosslinks. The interplex modulation allows independent control of the power levels of the two signals while maintaining a constant envelope, permitting use of saturated RF amplifiers.