RFtoLitetoRF
join:2002-08-11
Mechanicsville, VA
| reply to BillRoland
Re: digital cable and splitting
Yes, 20-27dB CNR is too low. Consider this...FCC spec for analog carrier CNR is >43dB, so if digital carriers are set 8-10dB below the analog carriers at the headend, corresponding minimum digital CNR would be about 33dB. The margin of headroom here is about 5-8dB, so minimum digital CNR is about 25dB. Less than this and the BitErrorRate begins to climb. This then creates the "tiling" of the picture. If your at 25dB now, any fluctuations is signal strength or purity will surely affect your reception.
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A job worth doing is worth doing right! |
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BillRoland
Premium
join:2001-01-21
Ocala, FL
clubs: | reply to Raydr
Would an SNR of 20-27 be considered too low for a digital cable box? |
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all_in_1
Premium
join:2002-07-05
Beatrice, NE
| reply to Raydr
said by Raydr:
Troubleshooting can really be a pain without a meter.
Like trying to find the bathroom in the dark.
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You need to set a time when you can be there when the tech arrives so you can show him, and see what he shows for levels at your sets.
FCC minimums for S/N is >43dbmv.
If your S/N is that low (20-30) an amp will not improve it.
IF you feel that you need to buy an amp, please buy one from Charter. At least you will get a quality product.
[text was edited by author 2002-08-27 23:22:14] |
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Raydr
Premium,MVM
join:2000-11-19
Carrollton, TX
 ·Verizon FIOS
| reply to gelbelt
Sorry, I forgot that service calls aren't set up for time frames. My bad. Heheheeh
Anyway, the cable box isn't going to help much with diagnostics, unless you carry it and a TV to each point where you want to test. If you have a cable modem...you probably want to use it instead. I go over this in my FAQ.
Troubleshooting can really be a pain without a meter.
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~Check out my Cable Modem/Wiring Issues FAQ~Please do not reuse my screenshots without asking!  |
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