Automatic meter reading
From Wikipedia, the free encyclopedia
Automatic meter reading, or AMR, is the technology of automatically collecting data from water meter or energy metering devices (water, gas, electric) and transferring that data to a central database for billing and/or analyzing. This means that billing can be based on actual consumption rather than on an estimate based on previous consumption, giving customers better control of their use of electric energy, gas usage, or water consumption.
AMR technologies include handheld, mobile and network technologies based on telephony platforms (wired and wireless), radio frequency (RF), or powerline transmission.
Contents |
[edit] Touch Technology AMR
With touch based AMR, a meter reader carries a handheld computer or data collection device with a wand or probe. The device automatically collects the readings from a meter by touching or placing the read probe in close proximity to a reading coil enclosed in the touchpad. When a button is pressed, the probe sends an interrogate signal to the touch module to collect the meter reading. The software in the device matches the serial number to one in the route database, and saves the meter reading for later download to a billing or data collection computer. Since the meter reader still has to go to the site of the meter, this is sometimes referred to as "on-site" AMR.
[edit] Radio Frequency AMR
Radio frequency based AMR can take many forms. The more common ones are Handheld, Mobile, and Fixed network. There are both two-way RF systems and one-way RF systems in use that use both licensed and unlicensed RF bands.
In a two way system, a radio transceiver normally sends a signal to a particular transmitter serial number, telling it to wake up from a resting state and transmit its data. The Meter attached transceiver and the reading transceiver both send and receive radio signals and data. In a one-way “bubble-up” type system, the transmitter broadcasts readings continuously every few seconds. This means the reading device can be a receiver only, and the meter AMR device a transmitter only. Data goes one way, from the meter AMR transmitter to the meter reading receiver. There are also hybrid systems that combine one-way and two-way technologies, using one-way communication for reading and two way communication for programming functions.
RF based meter reading usually eliminates the need for the meter reader to enter the property or home, or to locate and open an underground meter pit. The utility saves money by increased speed of reading, has lower liability from entering private property, and has less chance of missing reads because of being locked out from meter access.
[edit] Handheld
Handheld AMR is where a meter reader carries a handheld computer with a built-in or attached receiver/transceiver (radio frequency or touch) to collect meter readings from an AMR capable meter. This is sometimes referred to as "walk-by" meter reading since the meter reader walks by the locations where meters are installed as they go through their meter reading route. Handheld computers may also be used to manually enter readings without the use of AMR technology.
[edit] Mobile
Mobile or "Drive-by" meter reading is where a reading device is installed in a vehicle. The meter reader drives the vehicle while the reading device automatically collects the meter readings. Often for mobile meter reading the reading equipment includes navigational and mapping features provided by GPS and mapping software. With mobile meter reading, the reader does not normally have to read the meters in any particular route order, but just drives the service area until all meters are read. Components often consist of a laptop or proprietary computer, software, RF receiver/transceiver, and external vehicle antennas.
[edit] Fixed Network
Fixed Network AMR is a method where a network is permanently installed to capture meter readings. This method can consist of a series of antennas, towers, collectors, repeaters, or other permanently installed infrastructure to collect transmissions of meter readings from AMR capable meters and get the data to a central computer without a person in the field to collect it.
There are several types of network topologies in use to get the meter data back to a central computer. A star network is the most common, where a meter transmits its data to a central collector or repeater. Some systems use only collectors which receive and store data for processing. Others also use a repeater which forwards a reading from a more remote area back to a main collector without actually storing it. A repeater may forwarded by RF signal or sometimes is converted to a wired network such as telephone or IP network to get the data back to a collector.
Some manufacturers are developing mesh networks where meters themselves act as repeaters passing the data to nearby meters until it makes it to a main collector. A mesh network may save the infrastructure of many collection points, but is more data intensive on the meters. One issue with mesh networks it that battery operated ones may need more power for the increased frequency of transmitting. It also requires that the meter devices be transmitters as well as receivers potentially making individual transceiver cost higher. However, the additional cost may be outweighed by the savings of multiple collectors and repeater antennas and finding places to mount them.
[edit] RF technologies commonly used for AMR
- Narrow Band (single fixed radio frequency)
- Spread Spectrum
- Direct Sequence Spread Spectrum (DSSS)
- Frequency Hopping Spread Spectrum (FHSS)
[edit] Power Line Carrier AMR
Power Line Carrier (PLC) AMR is a method where electronic data is transmitted over power lines back to the central computer. This would be considered a fixed network type system, and is primarily used for electric meter reading. Some providers have interfaced gas and water meters to feed into a PLC type system.
[edit] Advanced AMR
Originally AMR devices just collected meter readings electronically and matched them with accounts. As technology has advanced, additional data can now be captured, stored, and transmitted to the main computer. This can include events alarms such as tamper, leak detection, low battery, or reverse flow. Many AMR devices can also do data logging. The logged data can be used to collect time of use data that can be used for water or energy use profiling, time of use billing, demand forecasting, rate of flow recording, leak detection, flow monitoring, etc.
