Hello:
I am having intermittent pixelation effects, most notably (but not exclusively) on one channel (811 on our cable system). It seems to be worse when the outside temperature is colder, which led me to suspect excessive signal level. We launched a service call, and the tech did indeed identify an excessive signal level. I had a 4-way drop amp (with a net 7dB of gain in each leg). He told me that gain was not required, removed it, and installed a passive 4-way splitter in its place. That should have dropped the overall signal by ~ 14 dB...
After replacing the split, he measured the signal at the farthest drop, and deemed it was fine. Things seemed OK for a day or two (maybe coincidence since the condition is intermittent), but then it was back again.
Thanks to the expertise in this forum, I learned how to invoke the diagnostic mode of the RNG200N [Select & Info buttons concurrently].
When I checked the RF properties of the suspect channel (was not bad at that moment), the level was -5 dBmV, and the SNR was toggling between 33 and 34 dB. The level seems OK, but the SNR is perhaps borderline. At least, I now have a benchmark to check against when the problem returns (or do I?, see below)
Here's the odd thing -- I looked at a variety of channels, expecting to at least see a roll-off across the broader frequency range. What I found however, was surprising because I got the exact same readings no matter what channel I was tuned to. Even stranger is the fact that the level, SNR, and frequency, is identical for every channel that I look at (QAM-256, -5 dBmV, 33 dB SNR, and 327 MHz). This makes no sense to me. Does the RNG200N always report diagnostics for only one channel regardless of which channel you are tuned to??? I know it is possible for multiple channels to share the same carrier, but these are HD channels so only two should fit, besides, I tried lots of different channels intentionally trying to find another frequency to no avail.
How can I see performance across frequency in order to help track down my intermittent pixelation on a select few channels? Or, am I even measuring the relevant performance numbers for my troubled channel 811?
-Thanks
Tom
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