dBmV & dB

[TheApocalyptican]

Found a script on another site to test the signals I am getting on my InfiniTV 4. It found that all my Signals are between -8.1 dBmV, and -12.7 dBmV, and I read on here that I want between 10 and -10, but preferably 7 and -7. For the SNR, I've go two frequencies at 35.6 dB, one at 36.2 dB, and all the other are between 32.8dB and 34.9 dB, and I read that the SNR should be 35+. Seems all the signals are low, and the SNR's are for the most part too. I've got problems getting channels to come in every once in a while, which is how I found the script, and seeing as how everything's low, could this be my problem? Should I be getting in touch with my cable company to adjust something? If I should, what should I be telling them needs to be adjusted? After going thru the problems getting my card paired, I'd like to be able to tell the cable company EXACTLY what I need done.



More info: Coming off of the main line into my house, I have a 1-in-2-out splitter, which one out goes to my media cabinet, which has a 1-in-3-out splitter which goes to a tv, a modem, and the tuning adapter/HTPC. The other line of the 1-in-2-out splitter goes to another splitter which, splits off to two bedrooms. Compared to some I've seen and read about, I don't have that many splitters, so it seems like the low signal is coming from the street.


Edit: read about splitters with a lower dB drop, and looked at my 1-3 splitter, and switched my tuning adapter/HTPC to the -3dB one. Got my dBmV up to a low of 8.8, and high of 5.2. Got more of the SNR's to over 35, but still have some as low as 33.6. Most are still below 35 though.

[barnabas1969]

The two-way splitter is dropping 3.5dB. The 3-way splitter sounds like one that has a -3dB output, and two -7dB outputs. If you have the 2-way splitter connected to the 3-way splitter, and the PC tuner is connected to the -3dB output of the 3-way splitter, then you are attenuating the signal 6.5dB. If you measure -5.2 to -8.8dB in this configuration, then you can calculate that the cable company is providing you with +1.3 to -2.3 dB at the point of entry. The cable company will probably tell you that this is normal/acceptable, which it is.

What this means is that you need an amplifier at the point of entry (before the first splitter) and/or to reduce the number of splitters. If possible, try to avoid connecting the output of a splitter to the input of another splitter.

An SNR of 33.6 is not terrible. It's OK. 35 is better, but 33.6 is OK. Check to make sure that all the connections are tight. Tighten them with a 7/16" wrench or a pair of pliers, not with your fingers. This might improve your SNR.

[TheApocalyptican]

Found a "hidden" splitter in the attic, that was unnecessary. With it removed, I'm now at a worst signal of -5.x, but the SNR still has several under 35, but I have many more above 35 now. Is a drop amp worth it, or am I good enough now?

[barnabas1969]

Good enough depends on whether or not you are experiencing any problems when tuning channels. If the SNR is a little low, AND the signal strength is low on the same channel, then you might have a problem. Otherwise, it should work OK.