There are two transmission techniques used in the ISM band, and they use different approaches to handle interference: 1. Direct-sequence spread spectrum (DSSS) is a spread spectrum wireless coding method that spreads the modulated information signal over a fixed frequency carrier signal. It uses suppression to mitigate interference.
Technology Transforms the Oil Patch By Russ Doig Over the past 10 years there has been a radical transformation taking place in the oil production industry that has been facilitated by communications technology. This transformation has lead to rapid advances in drilling, process automation, and plant operations technologies. Ultimately these advances have reduced the time to market for field development and reduced the lifting costs for oil and gas extraction. The ability to provide more cost effective bandwidth to drilling rigs has brought forth new applications and systems for rig operations. Drilling information systems now monitor all facets of the drilling operations both locally and remotely. These applications produce a real-time informational dashboard that displays operational parameters such as bit rotational speed, weight on
It’s C/I (carrier-to-interference) ratio is higher than that of a frequency hopping system. This means that a DSSS system can tolerate a higher noise floor and still maintain throughput. 2. Frequency-hopping spread spectrum (FHSS) is a spread spectrum technique that directly modulates a carrier that randomly hops between discrete frequencies within the band. It uses
bit, depth, direction, mud weight, etc. From this information the on-site rig staff can operate the rig more efficiently and remote engineers, geologists, and other experts can quickly come into play to diagnose and resolve issues. Other specialized applications can be brought into play for specialized drilling such as exploration. Real-time well logging and analysis allows geological and reservoir experts to quickly analyze exploratory drilling results. The end result is reduced costs for drilling because less time is required to drill a well, less staff is required on-site, drilling results are improved due to better information, and experts can manage multiple projects. The enabling communication technologies that make these applications possible are broadband wireless, wireless LAN, and direct broadcast digital and Internet satellite services. These systems allow drill rigs to be freed from the tether of point-topoint microwave systems and leased lines, which increases mobility, provides greater bandwidth, and reduces the need for human intervention
avoidance to mitigate interference. If it lands on a frequency that is in use, it retries on the next random frequency. As the noise floor rises, FHSS will hop more frequently to maintain connectivity. Excessive hopping decreases the data throughput and adds latency to the system. Both of these techniques use adaptive modulation schemes that increase the
when relocating. Use of VPNs and IP encryption technologies over the transport insures data integrity and security. High-speed secure networking has brought about change for production facility process control. Serial links and low speed SCADA systems are replaced by high-speed IP links supporting distributed process control automation systems. As with drilling, new applications provide a “dashboard” view of plant operations and control systems. The process systems take an incredible amount of data points and present the operations personnel with only the crucial information to do their jobs. In some cases the operations staff can do “what if” scenarios to simulate the effect of minor process changes on system operation and production efficiency to better tune day to day plant operations. Remote engineering staff can access views of the plant operation and historical data to do 22