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Procedure for In-System Utility Meter Ranging

IP.com Disclosure Number: IPCOM000241295D
Publication Date: 2015-Apr-14
Document File: 8 page(s) / 501K

Publishing Venue

The IP.com Prior Art Database

Related People

Daniel R Moore: INVENTOR

Abstract

It is useful for a utility meter in an AMI system to be able to determine the distance between itself and devices with which it may communicate. Periodic distance measurements may enable a utility to determine if a meter has been moved from its original installation point. The information can also be relayed to a head end to assist in isolating outages geographically. A well designed 900MHz mesh network may achieve point to point communication distances in excess of 2 miles. By combining a high-speed hardware timer and a pre-determined procedure, we can estimate the propagation delay of point to point messages and therefore estimate the distance between the two devices. This invention details a mechanism and procedure for ranging with a maximum accuracy of 5 to 50 meters.

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Elster Solutions, LLC

208 S. Rogers Lane, Raleigh, NC 27610

Inventors:  Daniel R. Moore

E20150100 -- Procedure for In-System Utility Meter Ranging

Background:

It is useful for a utility meter in an AMI system to be able to determine the distance between itself and devices with which it may communicate. Periodic distance measurements may enable a utility to determine if a meter has been moved from its original installation point. The information can also be relayed to a head end to assist in isolating outages geographically.

A well designed 900MHz mesh network may achieve point to point communication distances in excess of 2 miles. By combining a high-speed hardware timer and a pre-determined procedure, we can estimate the propagation delay of point to point messages and therefore estimate the distance between the two devices. This invention details a mechanism and procedure for ranging with a maximum accuracy of 5 to 50 meters.

Description:

It is useful for a utility meter in an AMI system to periodically determine the distance between itself and other devices with which it may communicate. Periodic distance measurements may enable a utility to determine if a meter has been moved from its original installation point. The information can also be relayed to a head end to assist in diagnosing erroneous installations, triangulation from known sources for coarse global positioning, or even isolating outages geographically or diagnosing erroneous

A well designed 900MHz mesh network may achieve point to point communication distances in excess of 2 miles. By combining a high-speed hardware timer and a pre-determined procedure, we can estimate the propagation delay of point to point messages and therefore estimate the distance between the two devices. This invention details a mechanism and procedure for ranging with a maximum accuracy of 10 to 100 meters depending on geographic interference.

The speed of light through a vacuum is exactly λ = 299,792,458m/s and through the atmosphere of the earth at sea-level is approximately λ = 299,700,000m/s. Thus, the delay of an RF signal is approximately 1ns/ft or 3.3ns/m. Modern SoC microcontrollers operate at the range of 100MHz to 300MHz (clock period of 10ns to 3.33ns). By measuring the roundtrip packet time, the meter can determine its distance relative to surrounding meters.

This invention ultimately ranges the devices by combining two procedures. The first is a low-speed clock synchronization procedure. This procedure allows the devices to mitigate the effects of low-speed transmission that would otherwise prevent ranging of devices. This is combined with a well-known RBS (Remote Broadcast Synchronization) procedure that allows for the actual ranging of meters. The approach is novel in that it optimizes for the fewest number of transmissions for accurate ranging and that the accuracy scales with the speed of the microcontroller timer. One generation of microcontrollers has seen a 10x increase in speed a...