prisoner3
join:2003-09-15
Lockport, NY
| reply to psldave
Re: Upstream off the chart: Downstream unchanged...
Actually you want that lower, definitely under + 58dBmV
which is the acceptable limit. The splitter will lower the dB slightly (higher before the splitter, lower after.) An
old cable installer trick is to put in an extra splitter if dB is too high. ( too high just as bad as too low)
Downstream channel of -18dBmV(-15 to +15 OK) looks bad, may need to be addressed. Let me know how the house call goes. |
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psldave
join:2003-07-31
Port Saint Lucie, FL
| said by prisoner3  :
Actually you want that lower, definitely under + 58dBmV
which is the acceptable limit. The splitter will lower the dB slightly (higher before the splitter, lower after.) An
old cable installer trick is to put in an extra splitter if dB is too high. ( too high just as bad as too low)
Since the upstream is how much power the modem is having to transmit back up the cable, adding splitters will only make the modem have to work even harder to get a connection. The modem's upstream is maxed now - adding a splitter now causes the connection to fail - the SNR upstream isn't good enough for a solid connection due to low signal level. |
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CableMan
join:2002-01-22
South Glens Falls, NY
| reply to prisoner3
did you reboot the modem when it was hooked up in the attic? your upstream(reverse) should have been lower if it was before all of the splitters. this is why most people will say "make sure it is off the first splitter". technically your upstream should have dropped down to almost 31-33 dBmV range.
56 is optimal but very close to the edge. is there an inhouse amp in the attic or before the attic?
your 47 up is fine but your -18 down is terrible. |
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psldave
join:2003-07-31
Port Saint Lucie, FL
| said by CableMan :
did you reboot the modem when it was hooked up in the attic?
The modem was off power for about 15 minutes while I moved it from the bedroom into the attic.
said by CableMan :
56 is optimal but very close to the edge. is there an inhouse amp in the attic or before the attic?
There are no amps that I know of. During the test, the modem was plugged into the cable before any splitters. Even on a (first) 2.3ghz two-way splitter, with 6 feet of RG-6, the upstream peaks at 58. I don't know what the upstream in the attic was before last week - I only know what it was in the bedroom, where it used to be 47dBmV... after two splitters (one of which was a FIVE way!).
said by CableMan :
your 47 up is fine but your -18 down is terrible.
Even at -18dBmV my SNR was still over 30, so I wasn't complaining  |
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