TiVo Community Forums Archives - Picture breakup

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Picture breakup - NTL or Tivo
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Posted by: andys

Hi,
I've just switched fom Sky to NTL (original not ex C&W) with a Di4010N STB. I've now noticed that a few recordings on my Tivo have picture breakup. I think that this is almost certainly an NTL problem, but given that I had to move everything around including my Tivo I can't be 100% sure. Anyone got any pointers to web pages etc. that give information on how to check out the signal strength etc. for NTL STB, or any other ideas how to work out which box is having problems. I guess I could just watch via AUX for a while but these days I almost never watch anything expect via my Tivo....

Thanks

Andy

Posted by: mjk

I have been using NTL for over a year, and recently have been noticing picture "stuttering" on some chanels. THe easy way to check if it is NTL or TiVo is to press the AUX button. This will send the input from NTL direct to the TV so you can check the input quality.

Posted by: andys

Thanks for the suggestion, problem is I don't watch live TV very often so most of the problems I see are on recrdings. In particular I've seen a number of problems on the Paramount channel (or whatever it is that has MASH on it). Do you have any info about how I can check the signal strength etc on the STB?

Posted by: gblades

Unplug the power to the STB and while holding down the up and down buttons on the front panel plug the power back in again. Release the buttons when 'diag' is displayed on the front panel.

Press the right button until you get to page 5 which shows the usefull information. Post the values here and I will have a look at them for you.

These instructions are for the Di4001N in the original NTL area but should be the same for your box.

Posted by: andys

Hi,
Ok I think this is the correct screen:

DVB Demod Status
Chan 531.000
QAM 064
Symbol rate 6.887
Tuner AGC 91%
IF AGC 50%
Pre RS Error 0.0e+0
Post RS Error 0.0e+0
SNR Est 35.9
Lock Locked

Hope this makes some sense.....

Thanks

Andy

Posted by: blokedownthepub

The tuner and IF agc's are the important bits, the tuner AGC is way too high suggesting the RF level hitting your box is way too low. Do you have any attenuators attacched to the RF connection into the box. If so try removing them.

The tuner AGC should really be between 35 and 65%. If the tuner is doing its work correctly then the IF AGC should sit at 62% pretty much constantly.

Too be honest I am surprised that is working at all. Where in the UK are you ?

Sorry, what I also should have said is get a Tech visit booked.

Posted by: andys

Yep it has a 6DB attenuator plugged into the feed. I'm in the Kirklees NTL area.

Andy

Posted by: blokedownthepub

Take it off, reboot and check the figures.

Posted by: andys

OK I'll give that a try as soon as my Tivo has stopped recording things!

Posted by: blokedownthepub

I editted my first response. You need a tech visit probably anyway as something has drastically reduced your levels. But see what happens when you remove the attenuator first.

Posted by: blokedownthepub

OT, so apologies, but I'm remenis? catching up. :D

How is Kirklees these days? I went to Polytechnic, in Huddersfield, which changed into University whilst I was there. I ended up staying for about 8 or 9 years. My last job in Huddersfield was working at the Emley Moor transmitter site.

Posted by: gblades

I would wait to see what the results are like without the attenuator. The SNR ratio is quite good so you should not be experiencing any signal problems because of it. However if the power drops lower briefly then you may have problems.

Post your results (5 values from AGC onwards) and then decide whether to book an engineer.

Posted by: blokedownthepub

Yep, the SNR is very good given the pants Tuner AGC.

Posted by: andys

I'll try things without the attenuator as soon as I get chance. They only installed the new STB yesterday (I had analogue NTL up until then - I'd already got Sky but wanted broadband). I did move things around after they left so maybe I've created a poor connection. What do you think?

Oh and Kirklees probably hasn't changed very much... weather is still dreadfull! I like it around here (most people have never heard of it!). The transmitter is still standing (unlike the previous one!).

Thanks

Andy

Posted by: blokedownthepub

Lol.
I've seen the Duty Engineers log entry for the night the last tower fell.
Apparently they got a phone call, not having noticed anything, or heard anything themselves.
Entry says TIME : Tower reported fallen.

Try tightening the RF connections into the STB and at the wall box. The AGC's will give you the best indication of whether the problem has gone or not.

Posted by: andys

Ok checked the connections seemed fine....

New readings without attn.

Tun AGC 57%
IF AGC 43%
Pre 0.0e+0
post 0.0e+0
Snr 37.5

So what do you think?

Posted by: blokedownthepub

Looks alot better. The AGC for IF is obvioulsy different on a 4010 box than I am used to. But looks good.

However those values are for only one transport stream, the one you were last watching. There are actually 24 transport streams going out. if you could tune to a channel which you have seen problems on, Paramount?. Then reboot intodiagnostics and report the values.

Tar.l

Posted by: andys

Ok tried paramount basically everything the same except for a slightly lower (36.8) SNR. So what do you think should I try it for a few days without the attn. ? Or should I call out ntl?

Thanks

Andy

Posted by: blokedownthepub

Try it without it. The levels are pretty much spot on central to what they should be. I am sorry to say unless you have somehow managed to dislodge something during your move about, it looks like you had a particularly bad install. I am sorry that this does not seem to be an occassional occurence.

There is the outside chance that your STB is effectively slightly 'deaf', no offence meant to anyone, and the attenuator would have been needed if you had a normally responsive box.

However I think it was a pants install.

Posted by: mjk

I was getting picture break-up this evening, and I went and checked my second box upstairs. THis was doing just fine, so I thought about swapping them over. However, first I tightened up the cable feed connection, and lo, the problems went away.

Posted by: andys

OK I'll go with leaving the attn. off for now. maybe I shouldn't have distracted the NTL guy with chat and coffee!

Thanks a lot for all of the help folks........

Andy