FIGURE 1. SDT SYSTEM CONFIGURATION
VorTek provides products and services dealing with the Seismic Detection of Tornadoes (SDT) concept, and the Site Assessment of Tornado Threat (SATT 3.0) software. Responsibility for two other concepts developed by VorTek, involving the Seismic Weigh-In-Motion (SWIM) system, and the Structural Acoustic Weigh-In-Motion (SAWIM) concept have been transferred to Smart Vibrations, LLC, a newly formed offshoot of VorTek. Subsection 3.1.1 deals with SDT products and services while subsection 3.1.2 describes the SATT 3.0 product.
The SDT system developed by VorTek is designed to be installed on a city-by-city or region-by-region basis in tornado-prone areas. For each such city or region the system consists of a network of SDT sensors or "Moles" which are buried approximately 1 foot beneath the surface and spaced approximately on a grid 10 miles apart. Approximately 29 Moles would be required to cover the metropolitan area surrounding an average tornado-prone city. Each Mole will be capable of detecting the tornado seismic signal produced by a tornado at ranges up to ten miles. Such signals can only be generated by a tornado which is in contact with the ground.
As shown in Figure 1, the Moles will be connected by a communication link to a Data Control Center (DCC). The DCC will be co-located with a broadcast agency, television and/or radio, with whom a contract will be signed. The signals received from the Moles will be processed and analyzed by the DCC. The processed data will be shared with the cooperating broadcast agency, which is broadcasting on a continuous 24-hour basis.
FIGURE 1. SDT SYSTEM CONFIGURATION
At the DCC, in cases when the seismic signals are determined to be produced by a tornado, a data modulation alarm message will be transmitted by the cooperating broadcast station to all SDT receivers or "Owls" in a specific region, within the metropolitan area which is threatened by the tornado. This alarm message will trigger an alarm to be sounded by each Owl in the region threatened by the tornado, thereby warning occupants of the building in which the Owl is installed to take appropriate action to protect themselves from the tornado.
VorTek will supply all the equipment that comprises the SDT system except for the transmitter provided by the cooperating television/radio station. Only the Owls will be for sale to the general public. All other equipment developed, supplied and/or installed by VorTek will remain the property of VorTek. The SDT System is unlike any existing tornado warning system and is covered by U.S. Patent 5,801,636.
VorTek provides two services: 1) tornado seismic data and 2) tornado alarm messages. The tornado seismic data is generated by the DCC and, as part of a contractual agreement, will be made available exclusively to the cooperating broadcast agency for its use in reporting tornadic events. In exchange the cooperating broadcast agency will 1) transmit the tornado alarm messages, 2) promote both the SDT network in general and the Owls in particular, and 3) pay an annual fee.
Each tornado alarm message is coded in such a way as to trigger only those Owls which are located in residences threatened by the tornado. To receive this signal each Owl owner must pay an annual subscription fee.
Recently VorTek has entered into an agreement with SurfSimple Technologies of Pleasonton, Califorina to provide SDT services to a number of counties located in tornado prone regions of the U.S.
VorTek has been granted a license from Engineering Analysis Inc. (EAI) for the unrestricted use and sale of the Site Assessment of Tornado Threat, Third Edition, (SATT 3.0 for Windows) software. SATT 3.0 provides the user with a means of quickly and accurately displaying and analyzing tornado data for any portion of the United States, excluding Alaska. This Windows-based program contains all National Weather Service (NWS) data from 1950 to 2006 and is designed to be updated annually. The 2007 data will be added as soon as it is available.
The SDT system consists of the Moles, the Data Control Center (DCC) and the Owls. The technology associated with each component is described in the discussion which follows.
As shown in Figure 4, the Mole consists of three parts: 1) a geophone, 2) a signal processor, and 3) a communication module. The geophone is a commercially available device commonly used for monitoring seismic signals produced by earthquakes, volcanic eruptions, and underground explosions. The output of the geophone will be sampled by a custom signal processor (designed and developed by VorTek) to determine if tornadic activity is present. This device will be able to discriminate between tornadoes and other seismic disturbances – including man-made disturbances produced by construction and transportation equipment. Finally, the communications module will transmit and receive information between the signal processor and the Data Control Center (DCC). When a tornado is detected an immediate message is sent to the DCC. Otherwise, status messages are periodically relayed to ensure that the Mole is healthy. Several "off-the-shelf" communications modules are commercially available today. VorTek will evaluate and integrate the most appropriate and cost-effective device into the Mole.
The Data Control Center (DCC) consists of: 1) a communication module, 2) a PC compatible computer, and 3) Data Control software. The communications module will be a commercial "off-the-shelf" device that is compatible with the transceiver chosen for the Moles. The computer will be a standard Pentium II system with appropriate microprocessor speed, memory, disk space, peripherals, and graphics to handle all of the tasks required to monitor, coordinate, and manage the Mole and Owl Networks. The Data Control software will periodically check the health of each Mole, receive warning messages from Moles, analyze and correlate seismic activity for tracking tornadoes, and generate an alarm signal to the Owl receivers to warn subscribers. The Data Control software will also provide a graphical output of the entire system status at any given time that can be feed to a television network for public broadcast.
The Owl consists of 1) a radio receiver, 2) an alarm device, 3) status lights, and 4) a test button. The radio receiver will operate continuously on A/C power with a battery backup and will be designed to detect and lock onto the coded signal that is transmitted from the television or radio station. When an alarm message is received by the Owl, a distinct audio alarm will sound a shrill warning and a warning light will flash. The audio alarm will also be used to alert the subscriber when the television/radio broadcast signal is lost or when battery backup power is low. In these cases, a periodic chirp will notify the subscriber to take corrective action. Other status lights and the test button will give the subscriber the ability to ensure the Owl is functioning properly.
Portable SDT instrument packages called "Snails" will be distributed annually during the primary tornado season to experienced stormchasers for deployment near tornadoes as part of an ongoing company-funded study. After each successful deployment the Snail will be recovered and returned to VorTek, where the stored seismic data will be downloaded and analyzed. By such a research program VorTek’s understanding of the tornadic seismic signal can be improved. Such improvements will be incorporated into the Company’s signal processor software in each Mole, as well as into the software associated with the Data Control Center, to improve discrimination and reduce false alarms.
A related research program involves cooperation with existing seismic network coordinators to recover any seismic data recorded by conventional seismic stations located within ten miles of a tornado. Such data records will be analyzed in a manner similar to that used in the analysis of the Snail data. Such analysis will also lead to an improved understanding of the tornadic seismic signal, which also can be used to refine the signal processor software, as well as the data collection center software.
A third research effort, which commenced during the SBIR contracts, involves developing a better understanding of how much energy is transferred from the tornado into the ground and how the energy is partitioned between vibration and thermal effects. This research effort will lead to a more accurate means for predicting the seismic detection range for tornadoes as a function of their intensity.
A fourth research effort involves participation by VorTek in a research project funded by Federal and/or state agencies. Both the National Oceanic and Atmospheric Administration (NOAA) and the Federal Emergency Management Agency (FEMA) have expressed a strong interest in the development and installation of a prototype SDT network in some tornado-prone region in the Southeast. The newly formed Severe Storms Research Center of the Georgia Tech Research Institute has also expressed a strong interest in such a program. The project would involve the installation of a SDT network, including both the Moles and the DCC, but not including any Owls. The DCC would be located adjacent to either a NWS and/or an EMA office in the tornado-prone region.
The final research effort involves the ongoing collection and analysis of seismic data recorded by the Moles which are part of any of the new warning networks installed by VorTek. In each such network approximately 12% of the Moles will be capable of storing seismic data produced by a tornado. This data will be collected, processed and analyzed in an effort to further enlarge and enhance VorTek’s understanding of the tornadic seismic signals. This research effort, like the first two, will provide a means for improving the performance of the Mole signal processor software as well as the Data Control Center software.
VorTek will provide all services and support to maintain the SDT networks which it installs and operates. Such services and support will include the test, calibration, and repair of all Moles and Data Control Centers. In addition, VorTek will provide, by means of the cooperating broadcast company, the necessary alarm signal to the Owls as a service to all subscribers, as well as customer support for the repair or replacement of defective Owls.
The current SDT system is designed for cities or regions with relatively large metropolitan populations. For cities with a small population or regions which are sparsely populated, a need for early warning of tornado touchdowns also exists. For small cities a smaller network, consisting of as few as a single Mole, may suffice, but for sparsely populated regions the network concept is not practical. For such cases some sort of Mole-Owl combination would be appropriate. For this case, the communication link from the Mole to the Data Control Center (DCC) and from the DCC (via the broadcast company) to the Owl and the subscriber are eliminated, with the Mole hard-wired directly to the Owl(s). As equipment costs are better defined and the signal processor software refined, such a Mole-Owl combination will be offered to residents in sparsely populated areas.