Communications

OVERVIEW

The IMS seismic system is designed around modern, digital communication networks. All of the communication technologies used by the IMS system are 100% compliant with standard and open networking protocols. This makes for seamless integration of the IMS system with existing IT networks.

The key communications technologies on which the IMS system operates are discussed below.

ETHERNET

Most IMS hardware products including netADC, netSP and UPS are Ethernet enabled. Any communications hardware providing an Ethernet interface is therefore supported for telemetry, monitoring and control. Examples include 100BASE-TX (standard “Fast Ethernet” over CAT5 cable), GSM/GPRS, WiFi, Fiber, xDSL, Satellite modem, etc.. This flexibility of communications options means that even the most remote locations are suitable sites for the IMS system.
 
 

WAVEFORMS OVER ETHERNET (WoE)

Waveforms Over Ethernet (WoE) is IMS’s digital streaming data transfer protocol designed to be carried by Ethernet compatible networks. WoE is used to transport digitized, uncompressed seismic data as well as monitoring and control information between the point of digitization (i.e. the netADC/sensor interface), via reliable Ethernet links, to a seismic processor (i.e. netSP).

WoE is 100% compliant with the open IEEE 803.2x Fast Ethernet standards, meaning that WoE networks are built from standard, commercial, off-the-shelf (COTS) networking components, e.g. cables, Network Interface Cards (NICs), media converters and switches.

WoE is a low overhead protocol, ensuring very low latency and maximal data throughput. Unlike higher level protocols such as the Transport Control Protocol (TCP) commonly used to browse the Internet, WoE is designed to run exclusively over reliable, switched network segments (LANs). Where a less reliable and/or lower bandwidth network segment exists, or network boundaries are crossed (i.e. via a router), higher level connection-based protocols are used.

Because WoE is standards compliant, it comfortably co-exists on existing local networks, e.g. business LANs. As the amount of data streamed over WoE increases, due to increased number of stations and/or higher composite sampling rates, a dedicated LAN or VLAN is recommended.

xDSL (ETHERNET EXTENSION)

DSL technology enables Ethernet links to be extended over a single pair of standard telephone-grade copper wire. This is especially attractive at sites where copper infrastructure already exists, and the significant additional cost of installing fiber is not feasible.

IMS DSL modems operate over distances of up to 7 km, at speeds of up to 5.4 Mbit/sec, and integrate the timing signal required for synchronisation of digitizers without a view of GPS satellites (i.e. underground stations), into the DSL-encoded data. This is a significant advantage over standard DSL communications, as it eliminates the need for a separate communications channel for timing, keeping the number of copper pairs and/or fibers down to one per link.

TCP/IP

TCP and IP are the ubiquitous technologies which enable the Internet and the World Wide Web. Their widespread use is leveraged by the IMS system to ensure maximum compatibility with existing IT networks.

TCP provides reliable, ordered delivery of data streams between hosts. IP handles the addressing and routing of data across networks. Together they provide the services required to reliably deliver data across complex networks, be it a mine, wide area network (WAN) or the Internet.

TCP/IP is used by the IMS system wherever reliable, ordered data transfer services are required, e.g. transfer of seismic events from netSP to Seismic Server or central database.

It should be noted, that the increased reliability of TCP/IP comes at the cost of increased latency, which limits its realtime performance. This is why WoE is used to transfer seismic data over smaller, more reliable and fast networks.

WEB TECHNOLOGY

Besides the transfer of raw seismic data from remote stations, the IMS stable includes a number of routine seismological and technical support services, all of which require 24/7 reliable connectivity to sites across the world.

In today’s corporate environment, security threats to IT networks are real, with potentially serious consequences. It’s not surprising then, that the most difficult part of establishing a data transfer service is often meeting the site-specific IT requirements. Furthermore, every network is different, with different security requirements, which can mean time consuming and expensive setup and maintenance procedures. IMS has extensive experience in working with corporate IT departments, and meeting their stringent security requirements.

Fortunately, most corporate networks have capabilities for effortlessly allowing secure and controlled Web access to specified hosts (e.g. Web browsing). IMS capitalises on this, by using custom, in-house tools based on Web technologies which are 100% compliant with standard IT security requirements, e.g. Authenticating Proxy Servers. So, all that is required to securely transfer the data required for round-the-clock services, is Web access.