CABL Forum - Re: Proper Output Levels At Tap

Many people have given similar advice, & good info. I'd just add a few things that may or may not help you in the future when you find problems like this(and please dont take offense if you already know most of this).

(1) The determining factor in what levels you need are dictated by the STB, CMTS, VoIP, etc. devices which require specific signal level ranges to input to them. So, if you know the spec of the digital STB RF input(probably -10 to +2 dbmv flat, on 256 QAM carriers...or somewhere close to this depending on exact manuf/model) then you should be able to reverse engineer your levels from your STB back through the customer's passives, and back to the tap. You already have your rough footage, and rolloff factors down...so it's just a matter of number crunching usually. As you've seen in this case...it doesnt take much crunching to know that this plant has some sort of issue, as others have pointed out as well.

(2) If you access to headend or OSP service techs, you could ask for access to the node to test your levels upstream of where you are, assuming you dont already have access to their nodes. If you find the problem only marginally better at the node itself, then you would want to get a headend tech or some tech that has access to the hub where your node is being fed from. Ask him to find the Tx that serves your node, and take a few sample readings.

(3) The HE/hub should have flat RF levels going into the Tx's, the node ideally should have enough tilt to account for the last mile into the customer's house. Obviously this tilt level is going to vary from tap to tap a little...but as a few others said...if the OSP was designed correctly & all components are working correctly, you should have a slight tilt at the tap to account for some of the reverse tilt(or I call it slope) that you will get from the tap into the customer's house.

Hope that helps a little.

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Re: Proper Output Levels At Tap