The electromagnetic spectrum is a crowded place, especi […]
The electromagnetic spectrum is a crowded place, especially between DC and about 6 GHz. The spectrum chart below is basically impossible to read – not just because in this case it is so small, but also because every bit of it is allocated for a service or services.
Although cable of all types tends to be overshadowed by other, more “glamorous”, technologies, they are nevertheless essential elements in just about any security system. One of cable’s most important components is the shielding that keeps stray electrical and radio-frequency signals outside and signals running through the cables inside.In many applications, shielding is not an option but a mandatory requirement.
Since there are several shielding types, it is important to understand the applications for which each one is best suited.Shielded cable was once chosen only for the most obvious, horrendously noisy environments; however, today that description applies to more places than ever even supposedly benign environments such as plenums where cables remain largely forgotten for years.
The types of shielding for various types of cables have not changed much over the years what has changed is the effectiveness of shielded cables, which has continually improved year after year. Although there is no such thing as a perfectly-shielded cable, the amount of attenuation that can now be achieved is so high that what interference remains should not degrade performance.
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