Structural Return Loss (SRL) expresses the amount of signal lost in negative terms, and occurs when signals reflect back to points of transmission. This prevents the signal from reaching the receiver, thus increasing attenuation. If SRL problems exist and attenuate the signal, ghosting, "snow" or complete loss of the channel signal may occur. (See Graphs below which illustrate the effects of SRL spikes on cable attenuation over frequency.)

Effect of SLR Spikes on Attenuation

Periodicity refers to the uniformly spaced variations in the conductor or dielectric diameter of a transmission cable. Reflections of the signal may occur when its wavelength, or a multiple thereof, is equal to the distance between two diameter variations.

Both of these signal degradation problems can be regulated by controlling tolerances of the diameter of the cable and by using gas injection in manufacturing. Belden guarantees all drop cable produced utilizes gas - injected dielectric, reducing attenuation.

Belden utilizes sophisticated quality control equipment and tools, such as Statistical Process Control (SPC), and adheres to strict quality assurance methods to secure the consistency of the manufactured product. These manufacturing and quality assurance methods reduce SRL and periodicity problems, allowing the customer who buys cable sweep tested to GHz to actually use bandwidth to that frequency.