What is the signal rule when going upstream in a system?

When analyzing the behavior of signals in upstream transmission within a cable system, the proper understanding is that the signal must typically be high at the Customer Premises Equipment (CPE) and low at the TAP (Transmission Access Point). This is due to the nature of the coaxial cable system where signals have to travel significant distances.

As the signal travels upstream, it experiences losses due to attenuation from the cable itself, as well as noise and other interference. Therefore, a higher signal level at the CPE ensures that enough strength is maintained as the signal travels to the TAP, allowing it to be adequately received and processed. In direct contrast, loss of signal strength at the TAP indicates that the signal has been subject to these various forms of degradation.

This understanding is crucial because it informs technicians about adjustments or troubleshooting that may be needed in the system. A technician would expect to find a higher signal originating from a well-functioning CPE, diminishing as the signal continues upstream due to various factors affecting propagation.