Stevens Telemetry and Wireless Data Communications
Overview information on:
Stevens Background in Telemetry Applications
Data telemetry can simplify and speed 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. Stevens is a leader in wireless solutions, providing a full range of capabilities to its customers for fast, simple and cost-effective data collection from remote locations. The company offers a choice of solutions, from long-range wireless satellite telemetry to short-range Bluetooth wireless technology.
Stevens is the designated ORBCOMM Value Added Reseller (VAR) for environmental monitoring in the United States and was the first company to transmit environmental data using the ORBCOMM satellite system. Stevens also designs and manufactures certified Geostationary Satellite (GOES) transmitters and receivers. In the United States, a GOES transmitter is certified by NOAA / NESDIS for transmission of environmental monitoring data and homeland security applications. Stevens is also certified using the GMS ( Japan) and INSAT ( India) geostationary satellite systems, and works closely with Eumetsat, the regulatory authority for Europe’s Meteosat satellite.
For short-range wireless communications, Stevens is a member of the Bluetooth Special Interest Group and designs and manufactures products that utilize the Bluetooth wireless technology.Wireless Options in Environmental Monitoring Applications
Wireless communication architectures are 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.
However, a range of choice is added with the numerous types of communication modems built to capture these signals. These modems and their respective frequency bands include:
Country of Use
|Bluetooth||2,400 - 2,483 MHz|
USA & Australia
|Spread Spectrum||902 - 928 MHz, 2,400 - 2483.5 MHz|
|Very High Frequency (VHF)||30 to 300 MHz|
|Ultra High Frequency (UHF)||300 to 1,000 MHz|
|Analog Cellular Modems||824 - 894 MHz||USA|
|GSM Digital Cellular Modems||1,850 - 1990 MHz
1,710 - 1840 MHz
|GOES Geostationary Satellite:
|401.7010 - 402.0985 MHz
|LEO (ORBCOMM) Satellite:
|148 - 150.05 MHz
137 to 138 MHz
|Wi-Fi (IEEE 802.11 a,b,g)||2,400 MHz & 5,800 MHz|
Factors to Consider
In addition to frequency band and modem output power, there are a few other factors to consider that influence the optimal r ange of communication. One is “line-of-sight” which means one antenna must “see” the other, without obstructions. Line-of-sight is not mandatory, but when available, greatly improves performance and range. This is especially true with higher radio frequencies where signal strength is reduced from obstructions such as walls, trees, foliage and concrete and eliminated with metal objects or structures.
Positioning, gain, antenna tuning, atmospheric conditions, time of day, ambient frequency, noise, and terrain are also important variables affecting RF signal and communication range.
Bouncing an RF signal off a satellite is one of the best options for remote installations, especially in locations where no other reliable RF or telephone coverage is available. Satellite is also recommended when infrastructure cost (such as the need to use repeaters for a non-satellite system) is an issue. There are two main types of satellite systems that offer remote environmental monitoring type applications: Low-Earth Orbit (LEO) and Geosynchronous Orbit (GEO). For more information and advantages and disadvantages of these different satellite systems, click on the following system of interest:
Satellite antennas are necessary for earth-to-satellite communication. Stevens offers several styles to fit various installation needs.
Radio telemetry is one method of transmitting data. Licensed and unlicensed radio telemetry may require line-of-site between the monitoring system and the base station. Antenna positioning, gain, tuning, ambient frequency, noise, atmospheric conditions and terrain are important variables affecting range -- however, transmissions can be repeated if interference is present. Click on any of the radio telemetry solution to learn more about the solution and its advantages & disadvantages:
A telephone telemetry connection is established between the two parties and the data is passed. While utilization of the wired Public Switch Telephone Network (PSTN) is a well establish and reliable telemetry solution, the technology and coverage of cellular data telemetry systems has greatly improved and rapidly gaining as an alternative to telephone or other telemetry solutions. Click on the following to learn more about the respective telephone telemetry system: