said by djrobx:I had to think about this one too
The signal level immediately from the node is always high so the node will be a able to feed everyone to the end of the trunk. So to achieve the 'target' level for the first customer in the line (people closer to the node) a high level attenuation tap should be used but this attenuation is not unidirectional (upstream and downstream) it affects both signals the same way so the modem to compensate for the added attenuation it has to increase its power output (upstream).
I had to think about this one. At first I thought attenuation being equal it wouldn't matter. Either you have attenuation from cable length, or you have artificial attenuation added from a high value tap.
Then I realized that cable-length attenuation impacts higher frequencies (where the downstreams are) more than low frequencies (where the upstreams are).
»www.w4rp.com/ref/coax.htmlThat means if attenuation is added to each tap that "targets", say, 0db at 500mhz, the upstream will skew stronger (lower modem output levels needed) as you go further away from the amp/node.