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Originally Posted by tveli /forum/post/0
also regarding the question of degradation of the picture - answer is no degradation unless its too much power/dB drop, in which case massive pixellation & freezing/disappearing of picture will occur. also tuning between channels might get slower as you near edge of acceptable signal power ; each split reduces power a tad, mostly/only on the downstream side of the split.
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Originally Posted by Weags /forum/post/20805225
... AND increase the upstream levels by around 3.5.
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Originally Posted by Ratman /forum/post/0
I'd double check on that. The splitter is passive. Upsteam levels from each device (I.E. STB and modem) will be unaffected.
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Originally Posted by Ratman /forum/post/0
I don't know... I have to question that logic.
Here's my thought. I agree the downstream signal power is halved (-3.5dB), that's common knowledge. One in... two out.
How can the upstream power be doubled? No matter which side is being fed upstream, it's two in, one out. BUT, the A feed will still be 50 and the B feed will be 50. Essentially each feed (going upstream) is an independant signal and level sharing one outboound pipe. A one to one relationship.
If your statement were true, if someone needed a "power/signal boost", why not just use a 2-way spliiter (or a 4-way for +7dB) in reverse instead of buying an amp?
And I know the difference between active and passive.![]()
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Originally Posted by Ratman /forum/post/0
However you want to justify it.
Here's what I have always understood:
A passive splitter cannot "increase" the signal on the return path. The same as that you cannot use a splitter in reverse (as a combiner) to gain signal.
If you could provide some technical reference to substantiate your statement(s) would be appreciated (and shut me up).![]()
OTOH, if you simply mean that a "cable modem" automatically compensates it's TX levels based on RX levels, that's entirely a different subject and nothing (per se) to do with a splitter.
Anyway... most cableco's will install the cable modem (if possible and as recommended) after the "first split" when it enters the premises.
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Originally Posted by Ratman /forum/post/0
OTOH, if you simply mean that a "cable modem" automatically compensates it's TX levels based on RX levels, that's entirely a different subject and nothing (per se) to do with a splitter.
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...AND increase the upstream levels by around 3.5, so be aware if your cable Internet modem is going to be affected by this extra split as it would be more sensitive to upstream levels.
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Originally Posted by RCbridge /forum/post/0
Guys
This is the reason: the upstream transmit power is determined by the attenuation between the cable modem or STB and the CMTS, so if you increase the attenuation in that path the cable modem has to work harder to overcome the additional attenuation.
So adding another 2 way in line adds the 3.5db attenuation.
The modem will increase its upstream power from 50 to 53.5dbmv.
Typically the CMTS wants to receive the upstream frequency at 0dbmv, so it tells the modem or STB how much power it needs to put out to reach it at the desired level.
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Originally Posted by Ratman /forum/post/0
As I tried to suggest earlier, based on the RX attenuation. the MODEM increases TX power (as alluded to in post 11)... not the splitter. I have been clear since post #7.![]()
Thanks for stepping in to clear up the explanations.