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Mesh wireless technology should be considered as the backbone for remote gas detection in oil and gas exploration and transportation.

This is the message from RAE Systems UK.

Mesh radios speed up deployment and provide stable communications.

Manufacturers of wireless gas-detection systems have started to incorporate these technologies into their systems to address the shortcomings of earlier offerings.

To accommodate multiple transmissions within the same frequency band, the narrowband signal can be spread out.

The two most common methods for spreading the signal are frequency-hopping spread-spectrum (FHSS) and direct sequence spread-spectrum (DSSS).

In an FHSS system, the transmission frequency is randomly varied with time.

At any particular moment the system essentially operates using narrowband transmission, but because the modems are continuously jumping to different frequencies (up to 1,600 times a second), co-channel interference issues are greatly reduced.

In a DSSS system, the signal is spread over several frequencies and transmitted at the same time.

By injecting a spreading code into the data, the resultant narrowband signal is broadened.

The additional bits are configured in an exact sequence that allows multiple transmissions to simultaneously reside in the same spectral band.

The ordering also provides a method of correcting errors that may crop up during the wireless transmission.

The spreading of the signal also results in increased security because the signal appears similar to noise.

These types of signal-spreading technologies offer solutions for co-channel interference, but do not address the issue of bypassing obstacles.

The high operating power requirements of these modems also limits their use for wireless gas detection within the oil and gas industry.

The need exists to combine these capabilities with other technologies to make systems practical for applications such as air monitoring on an oil-drilling rig or onboard a petrochemical shipping vessel.

Mesh modems can automatically route the wireless signal to other nearby modems, allowing them to easily bypass obstacles and increase the transmission distance.

They can run for long periods of time because they require very little power to operate.

Mesh networks require minimal programming because the modems locate the best path back to a controller and connect automatically.

Any loss of signal is detected and the network identifies the best method to re-route the signal and heal itself.

Benefits of a mesh system include the reliability of the wireless signal.

Integrated routing function and self-healing of the network ensures delivery of data.

The inherent redundancy of a mesh system results in increased safety and reduced engineering design and system reconfiguration time.

RAE Systems offers intrinsically safe wireless gas detection networks based on 902.15.4 2.4G DSSS mesh technology.

Embedded mesh functionality ensures a stable wireless signal; self configuration of the network simplifies deployment.

The 2.4GHz modems are designed for use in oil and gas exploration applications such as drilling rigs.

Multiple channels and low output-power limits potential interference with other wireless equipment.

The frequency band has 16 different channels to choose from, so in case of high background noise, the system can switch to a friendlier channel.

The FMC-2000 Wireless Multi-Channel Controller features a built-in mesh radio wireless modem for the Meshguard family; four programmable SPDT relay outputs; built-in backup battery for up to 14 hours of operation; a stainless-steel enclosure; and the ability to manage up to 24 channels.

The Meshguard Battery-Operated Wireless Gas Detector features: built-in mesh-radio wireless modem; up to six months run time on a disposable battery; continuous display of gas concentration in ppm; loud audio and bright visual alarms; resistance to RFI and EMI; and weather resistance to IP-65.

RAE Systems UK

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