The lower the mhz, the less immuned the channel is, since all the channels under 10 mhz are usually a few khz analog voice channels or low bandwidth digital. Wideband (>1 mhz) systems feature massive amounts of ECC (compared to an analog walkie talkie) and spread spectrum to overcome any interference, even if they are on licensed spectrum. I would assume interference regulations are much stricter on channels used for analog voice rather than ECCed digital data.
Also no cable modem will "transmit" until it hears/finds the downstream channel and CSMA/CDs itself an upload timeslot to auth with the CMTS, same with cellphones. A cable co could just shut down the modems or issue restarts to the modems until the interference modem goes offline and the interference disappears.
Coax doesn't magically leak more at a higher frequency or based on direction. A cable modem and cable box can both jam the node. Sure a broken CE box hooked up to the coax can knock out the node, but that signal won't escape the coax.
upstream split has nothing to do with this »www.kramerfirm.com/pictures/disp ··· =4&pos=4
upstream and downstream will radiate
The real problem of upstream is the fact you need to replace every last circuit board on the HFC plant for that node. Every amp, repeater, line extender, node, etc. That costs a fortune, well, according to them everything does. The CEO can always use a larger monthly bonus. Just easier to sue FTTH away and use pay-per-gig to cut down on the traffic.