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Well I see. I'm still looking for any kind of patterns with the errors, but I guess unless rabbit has other ideas that only leaves changing out the C2V to something more directional and see if that resolves these signal errors. Is that fair to say (since two 3dB attenuators have been added and the signal errors still occur)?
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No, it is not fair to say that. If you look at your original tvfool report you will see that the signals received by the C2V are very strong, with large Noise Margins. This means that you can add a LOT more attenuation before the signals become too weak for the tuners.
http://www.tvfool.com/?option=com_wr...d24362e8886d03
If I were there with you, I would want to add much more attenuation to see if the errors were gone while still having enough signal strength for the tuner. The reason I feel that way is because of the many comments by other Roamio users about it not being able to handle strong signals.
Take another look at this Google search for roamio signals "too hot":
https://www.google.com/?gws_rd=ssl#q...+%22too+hot%22
http://www.epinions.com/review/TiVo_...587068548?sb=1
A DVR that can record more than one channel at a time must have more than one tuner. As ADTech said, there must be a splitter in the DVR to send the signals to multiple tuners. He and I both think that the DVR uses a zero gain splitter, which is a splitter with an amp that adds just enough gain to make up for the splitter losses.
You have already discovered that the TiVo values for SNR are not realistic because they are determined for cable use, not OTA use. It is my opinion that there is a similar problem with the acceptable levels of signal strength for the Roamio. The tuners are probably similar to the tuners in a TV, but the zero gain splitter was designed for cable signals that have a much more narrow range of strength than OTA signals. The engineer who designed the splitter was designing it for cable signals, not OTA signals, which could mean that it was never meant to handle such strong OTA signals.
There are two tests that you can do to see if my theory has any merit.
The first test would be to get several each of 10 dB and 20 dB inline attenuators to add to your attenuator collection. Add more attenuation between the C2V and the AC7 and see what happens to the errors; never mind about the signal strength as long as there is enough left for the tuner to decode the signals for proper reception. You have plenty of NM available before you get down to 0 NM. And you have plenty of dBm Pwr before you get down to -83 dBm, which is where you will reach the "digital cliff."
Earlier you said:
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So you are taking about inserting a two out splitter after the output of my AC7 combiner (one output to the Roamio and one output to a 2nd televison)? If so, I can try but it may be tough to catch since I don't have 2 TV's in the same room.
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I can understand how that might be difficult. Your basement TV is a 60-incher; it is a lot of work to move a large TV. That TV is a Panasonic VIERA TC-P60ST60, which is a nice TV with good reviews.
What I want you to do as a second test is to disconnect the antenna coax from the Roamio and connect it to the P60ST60 to see how it behaves with the same signals that were going to the Roamio. The results might give us a clue about what improvements can be made to your antenna system.
When I have more time, I will give you some more answers.