INDUSTRIAL WIRELESS MODEMS
Wireless communication has changed the way data can be transferred and viewed across locations.
Industrial wireless modem is a heavy-duty, high-quality device that accesses a private wireless data network or a wireless telephone system. It accepts serial data (typically using RS-232, RS-422, or RS-485 standards) and transmits it without wires to another device which receives and coverts it. Data is sent from one end to the other as if there were a cable.
Operation of a Wireless Modem
Industrial wireless modems (see http://www.teledesignsystems.com) use electromagnetic waves to transmit modulated data. This is done using radio modems as access points. Radio modems are radio frequency transceivers for serial data. They transmit to and receive signals from another matching radio modem. Access points are various junctures in the network that enable wireless network connectivity.
Advantages of a Wireless Modem
- Wireless modem offers greater extensibility as it allows users to share and extend the Cable/DSL/phone connection anywhere.
- These industrial modems significantly reduce the cost and time otherwise required in Ethernet cabling.
- Wireless modems assure mobility as they offer user the freedom to work on devices such as laptop or PDAs form home or office or from anywhere.
- Wireless modems, whether it is for a laptop modem or Internet modem or cell modem, are easy to install.
- Improved Efficiency Industrial wireless modems share computer peripherals and data files from anywhere within wireless network for greater efficiency.
Applications of a Industrial Wireless Modem
In today's world of wireless communication and mobile computing wireless modems find applications in many areas.
- They can be used to deliver all types of Internet and multimedia content like text, pictures, movies and music.
- Wireless modems are used for live video conferencing for business and medical users.
- Wireless modems provide data connectivity to large mass of mobile staff with their office applications.
- Industrial wireless modems also make data communication possible from places, which are not easily accessible or are dangerous to humans.
- Wireless modems are also useful in data communication over the large office or production setups where wired data communication is unviable due to high cost.
Important specifications for a wireless radio modems
It is important to understand the parameters to judge and select a wireless modem:
General specifications that iare important to consider when searching for industrial wireless modems include data transfer speed, network type, and bus or interface type.
- Modem speed is the maximum rate of data transfer modem can accommodate.
- Network types include Ethernet, CPCD, ISDN, GSM, and GPRS etc.
- Bus or Interface types include Type III card, PCI, Firewire and USB etc.
Radio Link specifications to consider when selecting wireless modems include frequency band and radio technique.
- The frequency band on wireless modems can be 900 MHz, 2.4 GHz, 5 GHz, 23 GHz, VHF, and UHF.
- Choices for radio technique include direct sequence spread spectrum or frequency hopping spread spectrum.
Performance specifications to consider when searching for industrial wireless modems include number of channels, maximum output power, and full duplex transmission.
- The number of channels refers to the number of transmitting and receiving channels the device has.
- The maximum output power is the transmission power of the device. It is defined as the strength of the signals emitted from the wireless modem.
- Full duplex devices can transmit and receive signals at the same time.
Selecting a right wireless modem for your application is very important. Consulting the expert in the field can save you a lot of time, money and future maintenance problems.
Industrial wireless technology has made it possible that processes can be monitored and data can be collated from a remote location. The developments have almost made day-to-day operations independent of human supervision. Today, the applications of wireless technology have entered every sphere of activity.
An assembly of transmitter, receivers, sensors, wireless media, etc. is deployed to study various parameters of natural resources. Research organizations and government agencies use these remote data collection systems.
For real-time monitoring applications, data can be posted to the Internet and easily made available using standard web browsers.
Water data collection
Data collection systems are installed at remote water bodies in order to study and analyze them. Quality sensors are used to constantly watch the planet's vast water resources. These systems usually monitor the following parameters:
- Water flow-water data collection
- Water level-water data collection
- Hydro-electric oxygen
- Temperature-water data collection
- Conductivity-water data collection
- Dissolved oxygen
- pH-water data collection
- Turbidity-water data collection
Oil and gas data collection
Efficiency and safety are often perquisitesa for the oil and gas industry. A constant keen monitoring is required as oil and gas plants are usually located in remote areas or at sea. It is highly desired that such sites be equipped with monitoring, alarming and controlling devices. SCADA systems, implemented using industrial wireless modem technology, play a vital role in this area.
Some key oil and gas data collection applications include:
- Detection of overflowing storage tanks-oil and gas data collection
- Detection of compressor failure-oil and gas data collection
- Detection of corrosion in transmission pipelines
- Production automation-oil and gas data collection
- Efficient, error free, real-time, centralized data collection
- Wireless data services and GPs to keep track of service vehicles used for maintenance
Environment data collection
Radio data acquisition systems allow a facility to maintain monitoring stations in remote areas and create large networks of industrial environmental sensors. Data regarding various environmental conditions is collected and then further used for study and research. Data can abe retrieved instantly by connecting monitoring instruments to a PC equipped with data loggers.
Environmental conditions that can be studied using such systems include:
- Weather statuas-environment data collection
- Agricultural research
- Air temperature-environment data collection
- Barometric pressure
- Rainfall-environment data collection
- Relative humiditya
- Solar radiation-environment data collection
- Wind speed and direction
Drones are unmanned aerial vehicles, also commonly called UAVs. A UAV is an airplane that does not have a pilot to operate it but uses software instruction to perform necessary tasks. The basic function of a drone is industrial data collection as well as military data collection. Drones are used for aerial surveys, pipeline inspection, etc.
Operation of a Drone
Drones use software instructions for operation and are governed by a human operator on the ground. The operator sends software instructions to the computer installed inside the drone using Radio Frequency signals.
Drones use two types of sensors:
- Sonar sensors: These generate sonar energy pulses and trace echoes. Only one reading can be saved in this type of sensor. This reading can be retrieved or overwritten.
- Teledensitometer sensors: These generate readings continuously and are stored in a temporary buffer. The operator can delete the existing data, archive the data and add new data.
Example of a Drone Operation
Industrial radio controlled drones can used to locate oil on the sea floor. They collect data from the seabed using sensors. The operators send instructions to the Drone, which command them to move over the sea floor, communicate its position using GPS, gather information, take measurements, pictures, etc. The collected information and calculations are sent back to the operator using software instructions for further processing.
Drones also find many other applications in the scientific research, civil and military applications. They are very useful in instances where the application poses a threat to the human life.
GPS stands for "Global Positioning System." This system uses wireless technology to operate; the entire system consists of satellites and receivers. As the name suggests, GPS is widely used to determine the exact geographic location of an entity.
The system is made up of 24 geo-synchronous satellites, which continuously transmit position. The GPS data collection happens through a GPS unit - equipment with capacity to send and receive signals to connect with satellites. This GPS unit then considers the relative position of at least 3 satellites and determines its absolute geographic position.
This is an error correction functionality that was built into the existing GPS systems. Also known as DGPS, differential GPS is used in applications where accurate and precise results are desired.
GPS data collection from a receiver at a known location is used to correct the data from a receiver at an unknown location. Both the receivers track the same GPS signal. The measurement of the difference in the positions of these two receivers is used to accurately determine the position.
Industrial Data Collection Using GPS
GPS was originally conceived as a navigation tool for military applications. With speedy developments in technology, GPS has improved its usability. It is now used in many areas as a navigation system and a tracking device, as well as for surveying and mapping.
Transmitting and receiving signals for the data collection are main functions of a GPS unit. The data thus collected can be used for further analysis and statistics.
Tracking systems is an area where GPS is used widely. It helps the central monitoring unit keep track of people and/or vehicles. For example: On a highway, industrial GPS systems are used to track the number of vehicles and use the data in determining the period when the highway is most busy.
Another area where GPS is extensively used is navigation systems. Navigation systems use maps to help users determine their exact location. GPS software can perform tasks like locating a unit or finding a route from one point to other using GPS coordinates. The software can also dynamically determine the shortest possible route from one point to another.
GPS is also extensively used in air and marine transportation as well as in applications such as oil exploration and construction. Many organizations such as municipal corporations and railroad companies also use GPS for identifying exact location of underground railway routes and undergrounds cabling and sewage systems.
MILITARY DATA COLLECTION
Wireless and remote RF communication is extremely important in defense operations and military data acquisition. Military officials are benefiting from the flexibility and safety provided by high-performance RF solutions for vehicle telemetry, robotic control, and enemy tracking.
Wireless communication technology provides a variety of useful functions for military mapping and data collection purposes. GPS (global positioning systems) and GIS (geographic information systems) are widely used in military data collection, as they are essentially spatial in nature.
GIS is a system similar to GPS using wireless technology. It deals with collection of information of geographically referenced data.
Some of the applications of wireless technology in military functions for data collection include:
- Minefield mapping-military data collection
- Command and control-military data collection
- Digital mapping and GIS, which help in warfare simulation, mission briefing, logistics management, etc.
- Terrain evaluation for finding elevations, target firing, planning path of tanks/carriers, etc.
- Naval operations, where various wireless gadgets are used to determine position in the sea, depth of the water, water currents, wave conditions, etc.
- Spying (with the use of Unmanned Aerial Vehicles)
NARROW BAND SPECTRUM
Many services and industries today use electromagnetic signals for communications, broadcast, air traffic navigation, etc. In such circumstances, it is quite possible that the signals will interfere with each other and result in loss of data or miscommunication. To avoid this, frequencies have been divided into bands or spectrums and allotted for specific services or applications. Since most of the applications use radio frequencies, the term 'radio frequency spectrum' was created.
A spectrum is divided into many channels. A narrow band spectrum has many channels within a single spectrum. A broadband on the other hand accommodates fewer channels and hence can be used for high-quality data and image applications.
As the frequency increases, the data transfer rate increases and the area of coverage decreases. Communication systems using a narrow band spectrum cover large area networks and utilize minimal industrial hardware such as industrial network controllers, industrial wireless gateways and modem antennas.
Features of narrow band spectrum systems:
- These systems use a wireless gateway for transmitting data within a range of 200,000 to 350,000 square feet.
- The systems transmit data at 4800/9600Bps (baud per second) or at 19.2Bps with transmitter power of 2W.
- The systems have a comparable data transmission rate to spread spectrum systems.
Licensed narrow spectrum band
The frequency spectrum is usually divided into free-to-use and licensed bands. Regulatory bodies in each country/region have defined some standards for usage of spectrums. Any application/industry/service using this band has to have prior approval from the concerned authority.
A particular band of frequency, 2.4 GHz to 2.4835 GHz in the narrow band spectrum, has been allotted to industrial applications and is commonly referred to as the industrial narrow band spectrum. The data used in industrial applications using narrow band spectrums is called narrow band spectrum data.
RADIO DATA ACQUISITION
Unlike with radio data acquisition, the expenses in wired installations are increasing, and so is the demand for distributed remote sensing, industrial data acquisition and control systems. All this has made wireless radio data acquisition technology very crucial in today's operations. Nowadays, industries are moving towards wireless communications to improve their products and processes and are implementing wireless networks that are cost effective, flexible, and smaller in size.
Data collection or data acquisition techniques, which employ radio telemetry, are called radio data acquisition systems. These systems reduce the hassles of complex cabling, high maintenance and offer cost-effective installations.
The RF (radio frequency) transceiver is the central component of a typical radio data acquisition system. A base station has a radio modem, which receives data from a remote station modem using the RS-232 or similar standard port connected to a computer.
Once set up, radio data acquisition can be remotely handled by the machines without human inspection or interference. These systems can be installed in both low-cost applications as well as high-end critical monitoring applications.
Radio data acquisition systems can be classified into two categories depending on their usage:
- Wide range data acquisition systems, which use technologies like GSM, GPRS, etc. and
- Narrow range systems based on wireless LAN technology.
Advantages radio data acquisition systems provide:
- These systems are easy to install and incur less installation cost.
- They can be connected to mobile sensors.
- These systems require less maintenance and servicing.
- They operate efficiently in RF dense environments.
- They can tolerate temperatures of -40oC to 80oC.
Some of the applications of radio data acquisition systems:
- Radio data acquisition systems are effective in locations known to have high levels of electro-magnetic interference (EMI). Power stations use these systems to monitor generating equipment and switching systems in high-EMI areas within plants.
- Applications that use high voltage use radio data acquisition systems heavily. A radio modem connected to data loggers and a PC is used to transmit real-time information from high-voltage platforms to a central controlling unit to monitor equipment status.
- Industrial radio data acquisition systems are used on assembly lines to examine the performance of the manufacturing process. These systems send information to production and quality control units that keep track of units that are not produced as desired.
- Radio data acquisition systems are used in automotive industries to test manufactured vehicles. A data acquisition system is connected to various points on the vehicle. A GPS (global positioning system) is also connected to the DA system. Using this set, a vehicle is tested under actual running condition.
Wireless communication has revolutionized industrial communications and radio modems are on the forefront of the revolution.
Industrial radio modems encode, transmit and decode the data. They use radio waves for data transmission. And this medium of transmission gives user a lot of advantage over the wired data transfer.
How industrial radio modems operate?
Radio models operate in a similar fashion to your radio station. There are three stages of communication:
- Data encoding: Transmitting radio modem takes data from the source system and encodes it
- Data transmission: Once encoded, the transmitting radio modem transmits the encoded data as radio waves with certain pre-defined frequency (Just like our radio station broadcasts the program)
- Data Reception: The receiving radio modem receives the radio waves transmitted on the pre-defined frequency (like our radio instrument), decodes the data to its original format and provides it to the connected device
Most radio modems have RS232, RS485 or RS422 ports for communicating with the devices they are connected with.
What are applications of radio modem?
Applications of radio modems are limited just by imagination. Today radio modems are used in video security applications to mining applications and from oil and gas platforms to sports. Here are some examples, which can help you visualize how you can make best use of radio modem technology:
- Video surveillance: Wired connectivity of video cameras used for surveillance systems in large, widespread geographic area has limitations. It is costly and difficult to maintain. Radio modems overcome this limitation. They transmit video surveillance information in the form of radio waves to central surveillance unit, where another radio modem receives it and decodes it. It saves huge wiring expense and maintenance costs.
- Mining: Mining is possibly the biggest industry using industrial radio modem communication. Radio modems find many applications in mining such as data communication between moving units to centralized data center, automated ore processing and water treatment applications.
- Oil Platforms: Wired data communication between offshore oil platforms and land based control units can be very expensive and difficult to maintain. Radio modems are used extensively for oil data acquisition systems.
- Sports: Sports are also not far behind in using radio modem technology. Long distance outdoor sports such as marathons, cycle races, and car rallies use of radio modems to keep track of participants at every crucial location.
Selecting the right radio modem
Though radio modems offer a great promise to the industrial world, they also come with technical limitations. The prominent factors affecting the performance of radio modems include:
- Transmitter power: The distance for which the receiving radio modem can receive the radio waves without any loss of data
- Receiver sensitivity: How sensitive is the receiving modem to catch faintest radio signals?
- Battery life: For how much time a radio model can function without changing or recharging the batteries?
- Terrain: Can the selected radio modem work on uneven terrain or does it require line of visibility to receive the radio signals?
- Antenna height: Antenna height can be a problem when radio modems are used in the cramped space or when a moving person carries them.
- Antenna feeder cable loss: how much power is lost while transmitting or receiving data from or to the antenna through the cable?
Selecting the right radio modem for your application is very important. Consulting the expert in the field (http://www.teledesignsystems.com) can save you a lot of time, money and future maintenance problems.
REMOTE DATA ACQUISITION
A simple definition of remote data acquisition is collecting information about a system or a process. The data thus collected is used to study various parameters of a system and the implications it would have on the dependent processes/systems.
The systems that enable supervision of remote processes for data collection are termed remote data acquisition or remote data collection systems. These systems are designed using PCs and other processor-based input/output modules conforming to RS-232 and RS-485 standards.
Almost all the remote data collection systems use a device called a radio data logger. A radio data logger is a device that collects data from distributed processes using wireless technology. It is used in the following applications with acquisition systems:
- Temperature sensors- remote data acquisition
- Pressure sensors and strain gauges
- Flow and speed sensors- remote data acquisition
- Current loop transmitters- remote data acquisition
- Weather and hydrological sensors
- Laboratory analytical instruments
Advantages of remote industrial data collection systems equipped with data loggers are:
- Easy installation
- Low cost of ownership
- Reliability and flexibility
- Lowered risk of electrical faults, lightening surges and other hazardous weather conditions
Remote Data collection is very crucial in process engineering applications. It assists evaluating and improving the efficiency, performance, accuracy, reliability and energy consumption of a system and/or process.
REMOTELY PILOTED VEHICLE
Researchers at the National Severe Storms Laboratory (NSSL) and the Universities of Arizona and Oklahoma developed the Remotely Piloted Vehicle - more commonly known as the RPV.
RPV consists of a small airplane containing:
- A simple autopilot - a circuitry for decoding the radio signal
- A GPS radio receiver
- A terminal node controller (TNC) for digitizing the radio signal and GPS signals
- A 2m-radio transmitter for sending the signal to a ground receiver
The ground station consists of a 2m radio receiver, a TNC, a laptop computer, automatic positioning reporting system (APRS) software, and software for decoding the radio signal.
RPV has been primarily developed for scientific expeditions at high altitude, where human expeditions are difficult and dangerous. So far it has been used to make thermo-dynamic soundings from the surface up to about 4 km of altitude. However, it has the capability of reaching at least 6 km of altitude within 30 min of takeoff. The RPV can send the collected data anytime during the ascent, the flight and the descent due to the use of advanced wireless communication technology. The data transmitted by the RPV can be received at any point within a radius of about 5 miles from the ground station.
One more novel feature of the RPV is its capability to fly in all weather conditions; the autopilot keeps the aircraft stable, while a GPS navigation system is used to determine its position and velocity. This data is transmitted every two seconds to the ground station. The autopilot then flies the aircraft from the ground with reference to a laptop display and a radio control. Therefore, the aircraft can fly within clouds and not become lost, and can be returned to its launch point for complete reuse. In recent tests, up to 10 soundings were performed in one day.
The RPV is practically risk-free because it is designed to make soundings within gliding distance of the launch site; descent and landing are done with the engine turned off, so that engine failure is not a serious concern.
The RPV presents a great potential for various scientific, military and civil applications. To name a few:
- Unmanned scientific expeditions at high altitude
- Land and water surveys and data collection
- Low altitude survey of volcanoes, forest fires and similar expeditions, where manned operations could be life threatening
Although the RPV is not likely to have a direct impact on the common man, it is poised to revolutionize the way various scientific, military and civil expeditions are conducted today.
RTK DATA LINK
RTK is an acronym for real-time kinematics. It is a technique used in areas where precision is paramount. RTK is a process of transmitting corrected GPS signals. The RTK data link has a reference receiver at an unknown location and one or more rover receivers. The corrected signal is transmitted from the reference receiver to the rover receivers.
GPS or Global Positioning System is used to accurately determine information about position. Differential GPS is used as a precision method to improve the accuracy of the calculation. However, RTK is employed in areas where performance of highest accuracy is desired. RTK assures a precision and accuracy level of 1 to 2 centimeters.
In the RTK, the reference receiver checks for errors, corrects the errors, formats the signals and sends it to the other GPS equipment. RTK data links are critical for collecting reliable and corrected GPS data. Factors like range, update rate, and error correction rate determine the quality of the RTK data link.
The RTK enabled GPS can be helpful in the following cases:
- Compensating for atmospheric delay
- Rectifying orbital errors and other variables in GPS geometry
- Increasing positioning accuracy up to within a centimeter
Many professionals, such as engineers, topographers, surveyors, etc. use RTK. It is extensively useful in civil engineering and dredging applications.
Advantages of RTK:
- It can be used both for precise position calculation as well as for navigation systems or automatic machine guidance.
- It provides advantages over other traditional positioning and tracking methods, increasing productivity and accuracy.
- GPS requires code phase signals, as well as the carrier phase to deliver the most accurate GPS information. RTK provides differential corrections to produce the most precise GPS positioning.
SCADA is an acronym for Supervisory Control and Data Acquisition. Its basic purpose is to remotely monitor various processes, gather real-time data and then analyze it. The development and use of SCADA can be tracked back to the 1960's, when simple input/output devices were used to remotely monitor operations in industrial applications. With advancements in technology, SCADA systems are now developed using high-end software, high-speed microprocessors, wireless technology, etc.
Components of the SCADA system
SCADA systems typically are made of four components:
- Master SCADA Unit - This is heart of the system and is centrally located under the operator's control.
- Remote SCADA Unit - This unit is installed from where the process is actually monitored. It gathers required data about the process and sends it to the master unit.
- Communication Mode - This unit transmits signals/data between the master unit and the remote unit. Communication mode can be a cable, wireless media, geo-synchronous satellite, etc.
- SCADA Software - The software is an interface between the operator and the units. It allows the operator to visualize and control the functions of the process.
Example of a SCADA system
To understand the operation of industrial SCADA, consider the following example: Several pipes fill up water tanks at some remote location, where human supervision may not be possible. Also it is difficult to monitor several pipes simultaneously. SCADA systems are installed in such instances. When a particular tank reaches its overflow level, the remote unit senses it and sends a signal to the master unit. An alarm is triggered at the master unit station and the operator is made aware of the condition. The operator can visualize the situation using the SCADA software and can appropriately regulate the valve of the required pipe.
As already explained, wireless media can also be a communication medium for the master unit and the remote unit. Systems using this type of media are termed "wireless SCADA systems." A few examples of wireless media are explained below.
- Spread Spectrum Radio - The frequency band for this is 900 MHz to 5.8GHz and is free for general pubic use. Spread spectrum radio modems are used to ensure efficient network communication.
- Microwave Radio - In this case signals are transmitted at high frequencies using parabolic dishes installed on towers or on the tops of buildings. However, one disadvantage of this communication is that transmission may get interrupted due to misalignment and/or atmospheric conditions.
- VHF/UHF Radio - This is an electromagnetic transmission with frequencies of 175MHz-450MGz-900MHz. Special antennas are required to receive these signals.
Benefits of a Wireless SCADA system
A perfectly designed wireless SCADA system offers the following benefits:
- Monitors in real time
- Minimizes the operational costs
- Provides direct information of system performance
- Improves system efficiency and performance
- Increases equipment life
- Reduces labor costs required for troubleshooting or servicing the equipment
- Automated report generation reduces errors in calculations and interpretations
- Uses advanced technologies
A telemetry system consists of a remote site and a control site. The remote site wireless telemetry device contains systems and processes whose parameters are to be monitored. It would ideally consist of instruments that measure flow, pressure, temperature, etc. of a process. A wireless telemetry device at a control site is equipped with monitoring systems, which supervise conditions of power failure, water level, battery voltage, intrusion, etc. Chart recorders, alarm control panels, and data loggers are used for this supervision.
Operation of a telemetry system
When a telemetry device at the remote site detects any abrupt behavior in the digital/analog inputs, it triggers a signal. This signal is carried to the control site. The control site telemetry device then decides the action to be taken depending on the received signal. It then sends a signal back to the remote site with necessary control actions. The communication between the control site and the remote site is, many times, done by wireless medium.
Wireless telemetry systems were implemented to eliminate the use of dedicated wires and circuits to transfer data between a remote site and a control site. A radio system operating on RF (radio frequency) provides single point and/or multi-point communication. This is often called RF telemetry.
Advancements and massive developments in wireless technology have scaled up the performance of RF telemetry systems. Wireless telemetry provides a cost-effective way to monitor remote sites without any delay or risk of broken circuits. Also, changing a wired system to a wireless system is done at minimal cost.
Applications of Wireless Telemetry
Wireless Telemetry is used in almost every activity of process engineering, chemical plants, irrigation projects, military, etc.
UNMANNED AERIAL VEHICLE
An unmanned aerial vehicle, also commonly called a UAV, is the latest innovation in pilot-less aircraft. UAVs were first used during the First World War. However, advanced developments in UAVs started around the 1970s. The basic function of a UAV is gathering data. However, it can also be used to carry missiles.
In the future, UAVs will be used for civilian missions like search, rescue, and patrol operations. They will also be used for aerial surveys, pipeline inspection, etc.
Operation of a UAV
The UAV has a computer on board and is monitored by humans on the ground, using industrial wireless technology and RF (radio frequency) signals. The UAV can fly and navigate itself using software instructions that are fed to the system before its launch. The software instructions have the mission plan downloaded into the UAV's software. The operator on the ground can change the mission plan by sending a new set of instructions using the RF signals. The instructions are used to decide the course path, circle target or return to base. The UAV continues to fly even if it loses track of the RF signals.
Types of UAVs
- Backpack UAV: These are small UAVs used in cities to patrol around and protect an object or area, such as a ship at port.
- Civilian UAV: These are used for civilian uses and scientific research. One such UAV was developed to provide cellular telephone service to remote areas.
- Combat UAV: These are specially devised to carry weapons and are designed such that radar cannot detect them.
Advantages of UAVs
- They are simple and conventional aircrafts with advanced technology.
- They are highly robust and reliable systems.
- They are smaller and cheaper than a piloted aircraft designed for similar jobs.
- They can be used in long missions that could exceed a pilot's physical endurance.
- They can be used in places where humans cannot practically operate.
Wireless technology offers a method of communication without cables or wires, using RF (radio frequency) waves or infrared (IrDA) waves. Information that can be sent over such media is called wireless data.
The need to readily connect any time, anywhere, particularly for data purposes, has increased by multifold recently and it has triggered the extensive research activities in the wireless domain. The factors that have accelerated the usage of wireless data transfer include vast improvements in digital signal processing, new standards such as the IEEE 802.11, the Wireless Application Protocol (WAP) and Bluetooth.
These developments are creating a revolution in wireless data capabilities, products and user interest. Wireless technology is extensively used at home and in the office. Many sectors have started using wireless data transfer considering the advantages it offers. These include:
- General laboratories
- Industrial units
- Automotive, marine and aerospace
- Seismic, geotechnical, and meteorology departments
- Medical and biomedical fields
All the sectors mentioned above use data for analysis and statistics. Data used to be collected using input/output devices, sensors, etc. and passed to the data processing center. This process was called remote data acquisition or data collection. However, this method had some drawbacks like huge setups, extensive cabling, and the costs incurred for the infrastructure.
Wireless data acquisition systems were implemented to overcome the limitations of conventional data collection setups. The advantages of these systems are:
- They offer customized software interfaces and applications.
- They provide significant savings in installation and infrastructure costs.
- They save time spent making contact measurements in hard-to-reach locations and in plugging and unplugging sensors.
- They increase safety by making it possible to maintain a safe distance from dangerous equipment and hazardous locations while making measurements.
WIRELESS MODEM MODELS
This section will explain various types of industrial-grade wireless modems that are used for commercial, military and industrial applications. Most of these modems come with integrated radios.
This is a mobile radio modem used to send data over the existing voice radio system. The modem is compatible with all mobile and hand-held radio brands. A key feature of this modem is that it automatically manages error-free data transfers. TS2000 comes with a menu-driven software installation kit and hence is very easy to install and operate.
Some of the key applications of this modem are:
- Automatic vehicle location
Traffic monitoring and control
- Differential GPS navigation
- Water and wastewater management
- Irrigation control
- Oil and gas field monitoring
- Security system management
TS4000 is a high-performance radio modem with advanced data processing architecture. It supports a data transfer rate of 19,200 bits per second over narrow channel bands. An important feature of this modem is the advanced packet data operation with store and forward data repeating. TS4000 has an in-built bit error rate monitoring function.
TS4000 is widely used in the following areas:
- Automatic vehicle location
- Traffic monitoring and control
- Differential GPS and RTK survey
- Water and wastewater management
- Irrigation control
- Oil and gas field remote monitoring
MDS modems are used where high system performance and data integrity are vital. They provide an increased data transfer rate of 19.2 kbps using digital signal processing technology.
Real-time communication is made possible using the transparent and asynchronous communication modes. MDS industrial modems operate efficiently even under conditions of interference and spurious signals.
Other advantages of this modem include rapid installation, compatibility with other MDS series radio modems, minimum maintenance, etc.
Applications of MDS modems:
- Gas/oil production and distribution
- Water, gas and electric utilities
- Traffic control
- Industrial process control
- Railroad communication systems
AUTOMATIC VEHICLE LOCATION
Automatic vehicle location, also known as AVL, is a computer-based vehicle locating system. These systems have gained popularity with advancements in wireless technology and GPS. AVLs can accurately determine the position of a vehicle and send it back to the controlling station. The position determination process and communication methods may vary depending on the requirements.
A basic AVL comprises a set of receivers, modems, antenna, and digital communications systems. A network connects to a base station (equipped with PC, receiver and interface) and communicates the exact location of the vehicle. An AVL system can help in vehicle data collection by pinpointing the latitude, longitude, and speed of the vehicle and appropriately rerouting the vehicle.
An advanced version of AVL can also have:
- Real-time passenger information
- Automatic passenger counters
- Automated fare payment systems
- Automatic stop annunciation
- Automated destination signs
Vehicle Component Monitoring
This vehicle locator can also be used for collecting data on trains. An important parameter that can be tracked is the temperature. Features like anti-detachment, anti-tamper and anti-tilt alarms are built into train location systems so that operational safety is achieved.
Advantages of an AVL:
- Improves the efficiency of the dispatching procedure
- Tracks the driver's adherence to a route
- Informs customers about the estimated time of arrival
- Communicates directly with drivers
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