# Macroblocking on specific channels?



## MeAbFab (Jul 29, 2019)

Wondering if anyone has thoughts on the following. Over the past several days, we've started experiencing macroblocking on about 7-8 channels, and can't figure out what the deal is. 

Background: I live in Astoria, NY, and have RCN as my cable and internet provider. I've got a six tuner bolt. Over the past week, my building (three units) had sporadic power outages that seems to have been caused by a bad feeder line from ConEd. That has been resolved, but now some tuning issues have cropped up with the TiVo. i.e. CNN, Channel 650, is pixelated and macroblocking, and occasionally showing video from another nearby channel. This is also happening on a few other channels. Sometimes it's watchable, other times it's completely disastrous. 

I chatted with RCN, and we went through a signal test from their end. Per RCN, everything was good from what they could tell. They suggested sending a tech out, but noted that if it was an issue with my equipment or wiring in my home, I'd be charged (which I declined to do at this time). I did walk over to the RCN center and switch out my cable card, which appeared to solve the issue briefly but then made no change. 

When I went to the troubleshooting digital TV signals page on the TiVo site, I went through the steps listed, but am having issues making heads or tails out of it. 

Tuning to an affected channel (when it's largely watchable), I get the following data points in the diagnostics screen: 

signal strength: 75%
SNR: 30 dB
RS Uncorrected: 488271 (and climbing) 
RS Corrected: 41465439 (and climbing faster than uncorrected)

The suggestions to resolve seem nebulous, so I'm wondering if anyone has thoughts or suggestions. Thanks!!


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## keithg1964 (Feb 2, 2006)

Signal strength is low.
SNR is on the edge,

Increase signal strength and the SNR should improve.

I have seen a single bad cable cause low strength.


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## DeltaOne (Sep 29, 2013)

MeAbFab said:


> signal strength: 75%
> SNR: 30 dB


When I'm checking signal strength and SNR I put each of the six tuners on our most-watched channels. Then check the Diagnostic's screen to get a feel where they all are. I have a Roamio Plus, if that makes a difference, but I feel the sweet spot for signal strength is 90 to 95% and SNR of 35 to 37 dB. You certainly don't want to see 100% since that can mean 100, 105, 110...who knows.

My Comcast feed is too hot...right now I'm running -15 dB of attenuation to bring the signal down.

At 75% and 30 dB your signal is too weak.

I would recommend checking each and every coax connector. Start at the street if you can...check every connector all the way to the back of your TiVo. Disconnect the connector...maybe insert/remove the center conductor a few times. I've even been known to "rake" it a few times with my pliers...to get the oxidation off. Don't laugh...I've seen this make a difference.

Beyond that...you'll have to roll a truck and hope you get a good tech that cares about checking signal levels.


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## JoeKustra (Dec 7, 2012)

MeAbFab said:


> Tuning to an affected channel (when it's largely watchable), I get the following data points in the diagnostics screen:
> 
> signal strength: 75%
> SNR: 30 dB
> ...


If you can watch the error counters move, there is a serious connection problem, OR the feed from RCN is bad on those channels. Check the frequencies of the good and bad channels. Your signal comes from different sources or amplifiers. If the bad channels are close in frequency, it's likely a bad amp. If there is no relationship between frequency and quality, I guess it could be a local cable/connector problem.

True, you could have a better signal, but that shouldn't cause such a noise problem. One last thing to test: get all the tuners on the same channel. That can be done easiest by watching the channel, then perform a restart. You want to eliminate the TiVo. All tuners should display about the same data.


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## kpeters59 (Jun 19, 2007)

So, I've fixed a few OTA TiVo's with a similar problem.

They were all kinda close to each other, which is about 10 miles from the Tower Farm. Which is pretty close, but so close that the antenna had to be moved to 'optimize' the signal.

What would happen, is that I could get some of the channels to be pretty much good, but another group would get blocky. If I re-orientated the Antenna so the 2nd was pretty good, the 1st group would get blocky.

Eventually I tried 2 of the 'Leaf' style antennas connected 'backwards' through a splitter and it appears to have solved all of them. Optimize each antenna for each 'group' separately with the 'other' antenna disconnected.

YMMV.

-KP


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## tommiet (Oct 28, 2005)

Spectrum let me borrow a DVR a couple of years ago when I was having an issue. They said it was my Tivo. When the same problem came up using their DVR, I just recorded it. Long story short.... Spectrum ended up changing out an amp down the street to fix my issue.


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