This paper is to discuss the various methods of gathering electronic gas measurement (EGM) data. There are various options when it comes to collecting EGM data in the Natural Gas Industry. Devices such as RTU’s, PLC’s and EFM’s are typically used to collect and store the data locally. The focus of this paper is on the various technologies used to remotely gather the information stored on these devices. Depending on each company’s needs, these collection options could range from someone physically connecting to a device to collection via a satellite system. Spread spectrum networks became increasingly popular over the years, which as a result introduced realized interference due to the number of networks installed. Many companies are utilizing IP technologies versus serial in order to combine other networks and protocols. Licensed networks have been utilized for quite some time and are still used to meet reliability requirements. Cellular networks are often used when there is no infrastructure available in that area. Cellular networks will of course have a reoccurring cost associated with them. Satellite technology is required in some remote and/or saturated areas. Satellite communications can be costlier but is the only option available in some areas.
Data Collection Methods
Spread Spectrum Radio
Spread Spectrum Radio operates in the ISM (Industrial Scientific and Medical) band. Spread Spectrum radios share either the 900 MHz band (902 – 928 MHz) or the 2.4 GHz band (2.4 – 2.4835 GHz). These radios also use frequency hopping, direct sequence, or a combination of the two to achieve the necessary requirements. Radios are configured to use these techniques to limit the amount of interference from other radios using the same band. When using spread spectrum,theusermustbesuretofollowbestpracticesastheyrelatetoRFtoachievereliablecommunications. FCC regulations on spread spectrum limit the transmitter output power to 1 Watt and the Effective Isotropic Radiated Power (EIRP) to 4 Watts.
