Indoor Transmitter Using Short-Cycle Spread Spectrum Signals
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Solution Overview
Problem
Existing position determination systems, such as GPS, face challenges in providing accurate position information indoors due to signal obstruction and interference, leading to errors and increased costs, especially when multiple synchronized transmitters are required to cover large areas.
Innovation Solution
A position information providing system using a spread spectrum signal from indoor transmitters that repeat a content message in a shorter cycle than satellite signals, allowing for accurate position determination without the need for synchronized clock times and reducing the number of transmitters required, while maintaining compatibility with satellite signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple synchronized transmitters are arranged in indoor areas to provide position information, then position determination can be achieved indoors, but the cost increases due to synchronization requirements and a large number of transmitters are needed to cover wide ranges
Solution Approach 1:
The patent creates a simplified copy of the GPS signal structure for indoor use. The indoor transmitter emits pseudorandom noise codes similar to GPS satellites, allowing standard GPS receivers to function indoors without requiring complex synchronized transmitter networks. This copying approach enables indoor positioning while avoiding the need for multiple synchronized transmitters.
Solution Approach 2:
The indoor transmitter uses a simple, inexpensive design that does not require atomic clocks or complex synchronization mechanisms. By accepting that indoor signals will be short-range and localized, the system avoids the high costs associated with maintaining synchronized transmitter networks, using instead a single low-cost transmitter per indoor location.
2Object-affected harmful factors
If transmitter output is limited to avoid interference, then signal interference is reduced, but the receivable range is restricted making it impossible to continuously acquire position information
Solution Approach 1:
The patent divides the positioning system into outdoor GPS satellite segments and indoor transmitter segments. Each segment operates independently with its own signal characteristics. The indoor transmitter uses unique pseudorandom codes that do not interfere with GPS signals, allowing both systems to coexist without requiring power reduction that would limit range.
Solution Approach 2:
The indoor transmitter emits signals periodically with a cycle structure similar to GPS navigation messages. By using periodic transmission with distinct timing patterns and pseudorandom codes, the system achieves wide coverage without causing interference to other systems, maintaining both low interference levels and adequate receivable range.
3Ease of manufacture
If conventional GPS receivers are used without modification, then hardware cost is reduced, but position determination accuracy deteriorates in indoor areas where satellite signals cannot penetrate
Solution Approach 1:
The indoor transmitter is designed to be universally compatible with existing GPS receivers. By emitting signals that mimic the structure and format of GPS satellite signals, the system enables standard receivers to function both outdoors with satellite signals and indoors with local transmitter signals, achieving multi-functionality without requiring different hardware for different environments.
4Adaptability or versatility
If indoor transmitters emit signals similar to GPS signals, then seamless indoor-outdoor positioning is achieved, but signal reflection and interference in indoor areas cause errors of several tens of meters
Solution Approach 1:
The patent creates a simplified copy of GPS signal structure for indoor use, copying only the essential pseudorandom code modulation format while using distinct codes and timing patterns. This allows seamless operation with standard receivers while the unique indoor signal characteristics prevent confusion with reflected GPS signals, maintaining accuracy despite indoor signal reflections.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables stable and accurate position information acquisition indoors with reduced costs and time, as the system can differentiate between satellite and indoor signals, allowing for seamless indoor and outdoor positioning without the need for complex synchronization.
Implementation Method 1
generating a spread spectrum signal including the position data
Data Source
AI summary
Provided is a position information providing system which can reduce a time required for acquiring position information. An indoor transmitter is adapted to provide position information by using a second positioning signal compatible with a first positioning signal which is a spread spectrum signal from each of a plurality of satellites. The indoor transmitter includes an EEPROM which stores therein position data for identifying an installation location thereof, an FPGA operable to generate a second positioning signal including the position data as a spread spectrum signal, and a transmitting section operable to transmit the spread spectrum signal. The second positioning signal is generated to repeat the same content in a cycle shorter than that of the first positioning signal.