MEASUREMENTS TO MIND (M2M) is a growing suite of Stevens products that embraces cloud-computing with an all-inclusive vision of shortening the communication path from the sensors to data on-line. That is, what the sensors MEASURE the MIND sees.
Data telemetry can simplify and speed up the acquisition of critical information from remote locations. Stevens has been a pioneer in telemetry applications for environmental data collection since its development of the first remote environmental monitoring telemetry system, Telemark, in 1939.
Stevens remote telemetry systems take advantage of the latest wireless communication systems to create integrated environmental data collection solutions. The most effective wireless communication technologies for environmental data include cellular, radio and satellite telemetry. We offer a choice of solutions from long-range wireless satellite telemetry to short-range Bluetooth wireless technology, providing a full range of capabilities to our customers for cost-effective data collection from remote locations.
Stevens designs and manufactures certified Geostationary Satellite (GOES) transmitters.
The Stevens Product Catalog is a handy reference—24 pages covering most major products.
Wireless communication architectures are relatively simple—they include a modem on each end that emits or receives a defined radio frequency (RF), and an antenna. Since radio waves or signals exhibit very different propagation characteristics depending on their frequency band, engineers design radio systems to take advantage of these characteristics.
Range: 100 m
Bluetooth is a simple two-way wireless (radio) specification for low-cost, low-power, short-range radio links between mobile PCs, smartphones, and electronic instruments. Bluetooth can be used to collect data from remote sites or as a main link to a hub site, with a private radio system used to extend out to another nearby telemetry modem.
While users may still visit a water monitoring location, they may want to communicate via their computer or smartphone without direct cable access to the data collection platform. They may want to install another telemetry modem within 100 meters of the data collection platform. These are good applications for Bluetooth wireless-enabled data loggers. The Stevens Shark RS232/RS485 Serial Port Adapter makes any data logger Bluetooth enabled.
Shark RS232/RS485 Bluetooth Serial Adapter
Range: 5 miles
Spread Spectrum radio communications offers organizations seeking to collect environmental monitoring information a robust short-range, low cost solution for transmission of 24-hour data. Government agencies and utilities, among others, rely on spread spectrum to rapidly transmit information on hydrological and meteorological events.
Radio Frequency (RF) organizations, aware of the demand for local radio communications for individual users, have allocated certain frequency bands to be used in a more flexible way. The oldest and most commonly used frequencies are 900 MHz and 2.4 GHz, often called the ISM bands ( Industrial, Scientific and Medical). The main characteristic of these bands is that they are unlicensed, which means that the frequencies are open for public use and require no registration or payment (apart from the radio hardware).
Range: 30 miles
In every country, the use of the radio spectrum is regulated by certain organizations. The FCC regulates North America and ETSI (European Telecommunications Standards Institute) regulates Europe. These regulators define the allocation of each radio frequency bandwidth: for TV and radio broadcasting, for telecommunication operators, for the military, for data transmissions, etc. The VHF or UHF frequency bands are commonly used. Usually, to transmit over a frequency band, you must obtain a communication license from one of these bodies, register your architecture and buy the right to use the frequency.
Environmental monitoring data are typically transmitted in packets through radio signals using VHF ("Very High Frequency" 30 - 300 MHz, also used for FM radio and television broadcasting) and UHF ("Ultra High Frequency" 300 - 1,000 MHz, also used for television and cellular phones) frequencies. In the United States, there are up to 50 different frequency ranges available in the VHF spectrum and as many as 1600 frequencies in the UHF spectrum. However, many of these frequencies are allocated for specific forms of wireless communication.
A typical VHF or UHF radio (good for up to 30 miles) is an electromagnetic transmission received by special antennas. A license from the FCC must be obtained and coverage is limited to special geographical boundaries. The regulation, licensing, and governing of the radio transmission spectrum varies from country to country. Many countries, for various purposes, provide license-free radio data transmission spectrums. Check with the spectrum management authority in your country for license-free data transmission regulations.
Range: 30 miles from tower
Cellular telemetry is an excellent choice for any monitoring station that is within range of a cellular tower—low capital and service costs, high bandwidth, 2-way communication, and it's fairly ubiquitous.
All analog and digital mobile phones use a network of base stations and antennas to cover a large area. The area a base station covers is called a cell; the spot where the base station and antennas are located is called a cell site. Cell sizes range from sixth tenths of a mile to thirty miles in radius (1 km to 50 km). GSM use much smaller cells, no more than 6 miles (10 km) across. A large carrier may use hundreds of cells.
Each cell site's radio base station uses a computerized 800 or 1900 MHz transceiver with an antenna to provide coverage. Each base station uses carefully chosen frequencies to reduce interference with neighboring cells. Narrowly directed sites cover tunnels, subways and specific roadways. The area served depends on topography, population, and traffic. In some GSM systems, a base station hierarchy exists, with pico cells covering building interiors, microcells covering selected outdoor areas, and macrocells providing more extensive coverage to wider areas.
Range: 1/3 of earth's surface
GEO satellites provide the kind of continuous monitoring necessary for intensive data analysis. By orbiting the equatorial plane of the Earth at a speed matching the Earth's rotation, these satellites can continuously stay above one position on the Earth's surface. Because they stay above a fixed spot on the surface, they provide a constant vigil for the atmospheric "triggers" for severe weather conditions such as tornadoes, flash floods, hail storms, and hurricanes. When these conditions develop these GEO satellites are able to monitor storm development and track their movements.
A GEO satellite's primary purpose is weather imagery to optimize forecasting. In addition to weather imagery, these satellites include instrumentation used in environmental monitoring communications via a relay system. In the United States, this relay system is known as the Geostationary Operational Environmental Satellite (GOES) Data Collection System (DCS). The world network of GEO satellites used with weather imagery and environmental monitoring communications include:
Range: everywhere on the planet
Low Earth Orbit (LEO) satellites are in an orbit about 400 to 800 miles above the Earth’s surface—far below geostationary (GEO) satellite orbit. Orbits lower than this are not stable, and will decay rapidly because of atmospheric drag.
A LEO satellite orbits a local horizon in approximately 20 minutes. The orbiting periods range anywhere from 90 minutes to two hours, at approximately 17,000 mph. LEOs are considered to have no delay. A LEO system must use a satellite-to-satellite hand-off to maintain communications and are best for short, narrowband communications. Once one satellite moves out of the area a new one will move in.
We have experience with and integrate with most LEO telecommunications transceivers, including those from Inmarsat, Orbcomm, SkyWave and others. If you're interested in a LEO telemetry system, please contact us.