Land-Based RF Ranging Receiver Using High Modulation Rates
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Solution Overview
Problem
Current land-based positioning systems using GNSS signals often suffer from limited accuracy due to satellite unavailability, especially in areas like open pit mines where satellite signals are blocked, and they rely on code phase measurements which provide less accurate results without real-time kinematic processing.
Innovation Solution
The system employs land-based transmitters that send ranging signals with high modulation rates (30 MHz or more) in the ISM or X-band, using time division multiple access to increase dynamic range and accuracy, and incorporates differential measurements and temporal offset information to enhance positioning precision, allowing for sub-meter accuracy without requiring relative motion or real-time kinematic processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If land-based transmitters use GPS style signals with code division multiple access, then the system can provide positioning functionality, but the accuracy is limited to several meters based on code phase measurements
Solution Approach 1:
The patent changes the modulation rate parameter from typical GPS rates (1 MHz or 10 MHz) to a high modulation rate of 30 MHz or more. This parameter change enables code phase measurements to achieve centimeter-level accuracy without requiring real-time kinematic processing, directly resolving the contradiction between improving accuracy and avoiding increased complexity
Solution Approach 2:
The patent introduces time division multiple access (TDMA) to dynamically allocate transmission time slots to different transmitters. This dynamic approach increases the dynamic range of the system and allows multiple transmitters to operate without continuous interference, enabling high accuracy positioning while managing system complexity
2Adaptability or versatility
If GNSS signals are used for positioning, then global coverage is achieved, but satellite signals are blocked in areas like open pit mines leading to limited accuracy or unavailable positioning
Solution Approach 1:
The patent introduces land-based transmitters as intermediary positioning sources that operate in the ISM or X-band frequencies. These transmitters are deployed within the region of interest (e.g., open pit mines) to provide local positioning coverage where GNSS signals are blocked, ensuring both availability and accuracy in challenging environments
Solution Approach 2:
The patent transitions from relying solely on satellite-based three-dimensional positioning to incorporating land-based transmitters that operate in a different frequency dimension (ISM or X-band vs. GNSS bands). This dimensional change allows the system to provide positioning in environments where traditional GNSS is unavailable
3Ease of operation
If code phase measurements are used for positioning, then the system can determine position without real-time kinematic processing, but the accuracy is limited to several meters
Solution Approach 1:
The patent changes the code modulation rate to 30 MHz or higher, which fundamentally alters the relationship between code phase measurement and positioning accuracy. At these high modulation rates, code phase measurements directly yield centimeter-level accuracy without requiring the complexity of real-time kinematic processing, thus maintaining ease of operation while dramatically improving precision
Data Source
AI summary
In a local positioning system, a receiver is adapted for receiving signals from a land-based transmitter. The receiver includes an analog decorrelator for decorrelating the transmitted spread spectrum signals. A down converter connected with an antenna may be spaced away from other portions of the receiver. The down converter down converts received ranging signals and provides them to the remotely spaced receiver portions. A signal line connecting the down converter to the receiver may be operable to transmit any two or more of a reference signal provided to the down converter, the down converted intermediate frequency signals provided to the receiver, and power provided to the down converter. The receiver may be positioned adjacent to or as part of a land-based transmitter. By determining positions of two or more antennas, the location of the associated transmitter is determined.