How much signal do you lose on a thousand feet of cable?

Answer 1

There are many factors that contribute to signal loss over a length of cable. The major factors are the frequency of the signal and the inherent losses of the cable. Cable quality is vital to ensure good signal transmission.

Another important factor is the quality of the cable driver and the receiver.

Additionally, the practical effect of signal loss varies depending on whether the signal is analog or digital. As the cable length increases, the signal voltage will decrease and the high frequency signals will be reduced more than lower frequencies. In an analog video signal, the visible result will be soft edges, smearing the image. Despite that, the signal will still remain valid even though a quality loss will be seen. With a digital signal, the receiver will continue to interpret the signal correctly until a certain level of signal loss is present. Once that level is reached, the picture will show some significant errors and very quickly will fail completely. A good quality digital cable receiver will adjust itself to capture a poor quality of signal but such receivers tend to be found only in professional level equipment.

There are wide variations in signal losses but some typical maximum cable lengths are:

Composite analog SD video with high quality co-ax cable - 1000 feet

Composite analog SD video with economy cable - less than 50 feet

SD digital video SDI (Broadcast format signal) - 1000 feet

HD digital video SDI (Broadcast format signal) - 300 feet

VGA analog signal on high quality co-ax cables - 300 feet

VGA analog signal on economy cables - 30 feet

HDMI on good quality cable - 75 feet

HDMI on economy cable - 20 feet

Optical fiber - thousands of feet up to miles