Kippzonen BSRN Scientific Solar Monitoring System Uživatelský manuál stáhnout pdf (Strana 34)

power available. This can be accomplished by obtaining information on the power supply from the

local power authority.

The minimum suggested protection on all crucial equipment (e.g., computers, trackers, line

powered data acquisition systems) is an uninterruptible power supply (UPS) capable of

maintaining the system during outages caused by electrical storm s, increased com m ercial

demand (brownouts) and automatic switching of grid loads due to equipment failures. Most of

these outages only require that the system maintain the equipment for less than 10 - 15 minutes;

often the interruption is for less than one or two seconds. Nevertheless surges or failures, even of

this short duration, will cause the resetting and/or failure of equipment with an inherent loss of

data.

Within the observatory, the complete power requirements, including design for future expansion,

must also be considered. Transformers, fusing and wiring must be capable of bearing the load

required to maintain the instrumentation. This problem is of particular concern when (1) individual

circuits are overloaded with computing and data acquisition equipment or (2) long line lengths are

required to conduct electrical power to distant field sites from a main panel.

3.4.3 Communication

At stations remote from network infrastructures, consideration must be given to transferring

information from the observation platform to the laboratory where data analyses are performed.

While formerly such data transfer took place by mailing information to the central processing

facility, first on paper and later on diskettes, today a plethora of options is available. The intent of

this section is to make the user aware of some of the possibilities available to transfer the

collected measurements to the platform(s) on which the analyses occur. Expertise on the

installation and operation of many of these methods should be available either from within national

meteorological services or through private-sector consultants.

For data transport within a complex between two computers, a simple method is through direct

serial or parallel communication. Many software operating systems now include built-in methods

to allow easy communications between two computers without the complexity of local area

networking.

Long-distance file transfer can be accomplished using normal telephone lines and high-speed

modems for direct communication between computers. The frequency of the data transfer and the

amount of data being transferred using this method will dictate both the temporal efficiency and

overall cost of this data transfer method. Most high-speed digital serial modems are capable of

transmitting data at about 40 kbs (kilobits per second). At this rate one Mb (megabyte) of data

could be transferred in just less than 3.5 minutes.

The rapid advancement of the internet and world-wide web have made transfer of data over long

distances much less expensive than using direct-dial telephone communications. Local internet

service providers, which can be accessed through telephone, digital modem or through local area

network connections provide a reliable and inexpensive means of delivering data over great

distances. The more normal means of connecting to the internet are now being supplemented

with direct line-of-site wireless and cellular telephone connectivity. Depending on the amount of

data to be transferred several different options can be selected, varying from real-time constant

connections to daily or less frequent data downloads.

When more than two computers are required to communicate, a simple Local Area Network (LAN)

can be easily established. Using standard protocols (often sold as part of the computer operating

system) and inexpensive adapters, several to hundreds of computers can communicate together,

sharing resources, at far greater data transfer rates than serial communications. For example,

data can be downloaded from a data acquisition system (e.g., Campbell Scientific CR7) using

serial protocols (either locally or through remote communication methods) onto a single computer

which is part of a network. This computer can then be accessed by many authorized users

through a LAN. Data can be downloaded from the computer communicating with the data

acquisition system through the network, or users can simply access the data from storage that

resides at the site of the observations.

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