Time Diversified Packet Protocol for AMR Clock Calibration
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Solution Overview
Problem
Automated meter reading systems face challenges in accurately determining the time of meter readings and preventing data loss due to temporary obstructions and clock inaccuracies in meter interface units (MIUs), which are costly and power-consuming to maintain with highly precise clocks.
Innovation Solution
Implementing a method where collectors receive data packets with elapsed time indicators from MIUs, allowing for clock calibration and accurate timestamping, even with non-sequential readings, and using two-way communication to reset or calibrate the MIU clock, shifting the cost and maintenance of precise timekeeping from MIUs to collectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If highly precise clocks are installed in MIUs to ensure accurate timestamping of meter readings, then measurement precision is improved, but device cost and power consumption increase
Solution Approach 1:
The patent extracts the timekeeping function from the MIU and relocates it to the collector. The MIU only records local elapsed time since the last reading, while the collector maintains the accurate system clock and calculates actual timestamps. This eliminates the need for expensive precise clocks in each MIU, reducing power consumption while maintaining timestamp accuracy.
Solution Approach 2:
The patent introduces an intermediary time representation method where the MIU stores only the elapsed time indicator (local timer) since the last reading, and the collector acts as the mediator that converts this local elapsed time into accurate timestamps using its own precise clock. This intermediary approach resolves the contradiction by separating time measurement from time recording.
2Device complexity
If data packets contain only sequential readings to reduce packet size, then device complexity is reduced, but reliability decreases due to data loss from temporary obstructions
Solution Approach 1:
The patent applies preliminary action by including non-sequential readings in the data packet in advance, before transmission occurs. This ensures that even if temporary obstructions cause some readings to be lost during transmission, the receiver still has access to sufficient temporal data points to reconstruct accurate timestamps and maintain reliability.
3Reliability
If the MIU transmits readings frequently to prevent data loss, then reliability is improved, but loss of time increases due to repeated transmissions of the same readings
Solution Approach 1:
The patent prepares multiple readings including non-sequential ones in advance within the data packet structure. This preliminary preparation allows the system to transmit less frequently while still maintaining reliability, because each transmission contains sufficient temporal information (multiple readings with elapsed time indicators) to reconstruct accurate timestamps even if transmissions are spaced further apart.
Data Source
AI summary
A method of reporting information from a meter interface unit to a receiving device in which a data packet is transferred from the meter interface unit containing meter readings, which are associated with an indicator of the elapsed time since the reading was taken. The receiving device compares this elapsed time value with the actual elapsed time, based upon the internal clock of the receiving device, in order to determine any inaccuracies in the clock of the meter interface unit. In another embodiment, the data packet includes at least two nonsequential meter readings, separated by a multiplicity of reading intervals, on a rolling basis, such that data will not be lost as a result of a temporary obstruction that interferes with the transmission or receipt of meter readings.