Attenuator questions

[Ziggy86]

We are having FiOS installed this weekend and I purchased a pack of attenuators in case I have pixellation issues. It came with 2 each of 3 db, 6 db, 10 db and 20 db.

Do I start with the highest (I assume 20 is the highest ) and if there is not fix work my way down to the lowest number or do I go the opposite way?

Sorry but I am a little confused.

Steven

[Dmon4u]

To quote bkdtv:

" Most people need closer to 10-12dB ", seems about right !

[mae]

At least in this area, they are using new ONTs (Alcatel) that don't seem to output as high a signal. As I posted in the main FIOS thread, http://www.tivocommunity.com/tivo-vb/showthread.php?p=7166889#post7166889, after my install last week, I have a 4-way split followed by a 2 way at the TiVo, and the DVR diagnostics give a value between 75 and 100% with SNRs ranging from 32 to 36 db (I've spent more time looking at most, if not all of the QAM channels and found some lower readings than my initial post-see next paragraph). There have been no pixelation issues (I've noticed), and on the lowest and highest signal/SNR channels I've been getting under 100 uncorrected errors (mostly <5) over a 12-24 hour period. That's actually a little less than I was getting from Comcast. I'm continuing various monitoring schemes while I'm still in my 15 day satisfaction window.

I've also installed a NIM-100 from e-bay in front of the TiVo. This gives much better download performance than the wireless adapter and strips out the MoCA frequencies. Since nothing in life or RF is free, insertion loss might account for the lower signal strengths/SNR's.

So I would let them do the install and see what levels they get on their Sunrise meter and the TiVo's diagnostics screen. If it isn't high by their (or TiVo's) readings-all over 100, >35db, I'd give it a chance and then start with a mid range attenuator and move up and down. I bought a variable attenuator from MCM which is still in the package. Being prepared is good, being surprised that it works OK is better!:D

[Chris8204]

Just make sure you test your Tivo at multiple times of the day and all channels. At night, all my channels seem to be ok, but during the day ESPNHD and a couple others on the same QAM frequency have lots of errors and pixelation. I'm using a low pass filter and tried every combination of attenuators with no luck. Hopefully this won't happen for you, but my point is that you need to check all the frequencies at different times of the day because it's possible that only 3-4 channels have problems and the problems come and go. I also have a motorolla dvr from fios and of course the moto box never has any issues.

[Ziggy86]

Chris,

Are you using one of the newer ONT's? How long ago was your FiOS TV installed?

[mae]

Just make sure you test your Tivo at multiple times of the day and all channels. At night, all my channels seem to be ok, but during the day ESPNHD and a couple others on the same QAM frequency have lots of errors and pixelation. I'm using a low pass filter and tried every combination of attenuators with no luck. Hopefully this won't happen for you, but my point is that you need to check all the frequencies at different times of the day because it's possible that only 3-4 channels have problems and the problems come and go. I also have a motorolla dvr from fios and of course the moto box never has any issues.
Chris,

Where are you located and what VHO are you on? I haven't noticed anything on ESPN HD, but I'll add it to the rotation.

Thanks.

Mark

[sinanju]

I'm not sure why you would buy a pack of attenuators... Verizon installers have them. They also have detailed instructions, in the form of a tech notice issued last year, concerning what measurements to take in order to apply the attenuation patch. In my experience, they're also willing to leave behind any number of attenuators of various values to enable you to tweak as necessary.

In my experience, the lower QAM frequencies are the first to be driven off the bottom by over-attenuation:


Channels: 628, 639 @ 123MHz
Channels: 585, 625 @ 117MHz
Channels: 622, 630 @ 111MHz

The local channels seem to be the first driven over the top by under-attenuation.