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Posted by Timothy Daniels on September 14, 2006, 1:08 am
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*TimDaniels*
"Ed Nielsen" wrote:
> Cable systems are designed for a signal level of 15-20dBmV at the tap
> and every tap, splitter, directional coupler, etc. is well documented.
> They know just what is where. Changing out a tap in order to get more
> signal at a specific location may very well affect the signal levels
> downstream as well as upstream, as different value taps have different
> insertion losses, not to mention that the system would go down while
> that tap is being replaced. Back to one of the reasons why so many
> people hated cable TV years ago -- frequent outages.
>
> Systems that have been upgraded to provide advanced services typically
> run at 20dBmV at the tap, which, after an 85' drop is 15dBmV at the
> groundblock, which is fine for 4 outlets. Install a DC-9 prior to the
> 4-way splitter for the cable modem and everything is happy.
>
> If there is 15dBmV at the tap, the same 85' drop turns that into 10 at
> the groundblock. A 4-way splitter makes that 3dBmV leaving the splitter
> to feed the outlets. A 50' run to the outlet then drops that down to
> +0.1dBmV at the outlet. Still meets FCC specs and if there is a DCT or
> a pretty new cable ready TV at the outlet and all of the connections are
> good (includes tight), then all is well. However, if there is a 10-year
> old cable ready TV set that has less than optimal shielding integrity at
> the tuner, ingress takes control and locals really suck, as do some of
> the other channels. If the homeowner or tenant moves the room around
> and needs a longer cable to go from the outlet to the TV set, they run
> down to Wally-World and buy one. It doesn't have the shielding
> integrity needed and pictures are a mess. Ingress is the reason I
> prefer to have no less than +5dBmV at the outlet, even though the FCC
> says 0dBmV.
>
>
> CIAO!
>
> Ed N.
>
> Timothy Daniels wrote:
>> My impression from talking with several techs in
>> the So. Calif. area as they did their installations for
>> customers in our condo building is that they'll give you
>> enough signal strength to accommodate a 4-way split
>> for TV. If they determine where the splitters are put in
>> the residence they'll do what's necessary to *still* give
>> you enough signal strength for a 4-way split on the TV
>> legs and assure proper signal level for the modem.
>> As long as they know what the setup will be inside the
>> home, they'll do that because it's in their company's
>> financial interest to:
>> 1) Assure a good picture on the TV sets,
>> 2) Good signal level for the modem, and
>> 3) Avoid future callbacks.
>>
>> My impression from conversations with the field tech's
>> supervisors is that this policy may stem more from the
>> supervisors' interpretation of the company's "culture"
>> than written company policy. Given that, I think that the
>> more you can tell the field tech what your ultimate
>> configuration will be, the more likely he'll be to accommo-
>> date your needs in signal strength.
>>
>> *TimDaniels*
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