Topfield signal quality

[pi314]

I've been having a few issues with my Topfield 7260 lately, such as occasional repeated frames, and decided to try jdaSignalMonitor to check my signal strength and quality levels.

For all channels, signal strength is 89. My understanding is that anything in the 60-90 range is fine. (Sort of surprise how consist this value was though.)

With signal quality, values vary quite a bit. Sometime the lowest value is high (98), other times it can be around 87-92, and even occasionally 0.

For signal quality, what is required to decoded signals without errors? Are my signal levels normal? If not, what can I do to improve them?

 

Edited February 5, 2017 by pi314

[pgdownload]

Hi 3 (I generally round down). Tuner quality is fairly meaningless. Signal strength is less so but what a TAP reports a tuner is reporting is also pretty wishy washy. Added to that is that "89" means nothing really. Its roughly 9 out of an arbitrary 10 and no doubt better than a 69. 

At what point (strength) a tuner starts having difficulty decoding a signal is also fairly individual to each machine.

All that said. 89 should be more than plenty for a good signal. Digital TV doesn't degrade as the signal strength decreases. It continues showing a 100% picture until it gets to what's called the "digital cliff". In your case with your Toppy, that might mean a strength of 88 or (more likely 78) etc. At this point the picture rapidly descends into unwatchable.

FWIW repeated frames doesn't seem like a signal strength issue IMO. You don't mention the other issues.

You could see if these issues occur live and also during playback of a recording and if the do affect recordings do they happen at the same point after you skip back?

If you're really concerned get an antenna guy in to check out your signal strength with proper kit. I'd be very confident you have normal levels though.

I assume you don't split the signals of the antenna to other equipment? If you want to you could also get a booster (2 way) and send a separate lead to each Toppy tuner plug.

Something like this

Regards

Peter Gillespie

[pi314]

Thanks for the reply.

I will have to watch live sometime and see it occurs. (I mainly watch recorded material.)

Yes, recordings are affected. If I skip back, the issues are always present at exactly the same point. They are also present when the recorded files are viewed on a computer.

What would cause a lost frame and/or a repeated frame, assuming it was not already present in the transmitted signal?

Trying the jdaSignalMonitor TAP was prompted by another earlier thread:

http://www.dtvforum.info/index.php?/topic/225452-frame-rate-conversion-of-us-tv-shows/

In that thread I post a link to a couple short recordings that show some of the issues I'm currently having.

One of the later posts by MLXXX gives a very nice analysis of what is occurring in those two recordings.

[pgdownload]

Hadn't made the connection with that thread. The issue definitely isn't reception or signal strength. That would cause random effects in the result not such consistent issue in the data stream. It would also likely affect more than a single frame every time.The issue only occurs on SBS which also makes signal strength much less likely.

IMO something in the Topfield is the cause. Its beyond my capability but it would be interesting to see the actual "dropped" frame in the original mux (your MPG files would be a translation of the original files I believe). The 29th frame would be a bunch of information presumably but something in the headers/data is causing the Toppy to skip it.

Regards

Peter Gillespie

PS my only other suggestion is find a show this is happening on and record it on the Toppy. During which time watch it live (via the TV tuner). See if it doesn't occur on the TV  but does on the Toppy (when you play it back latter) - my guess is that's what would happen.

[pi314]

Currently virtually all my tv watching consists of the various ABC and SBS channels. At least once, I have seen the issue on ABC HD as well. It's possible that I witnessed additional instances on the ABC channels but, as I didn't make a note of them, I can't say for sure.

I'm not sure what you mean by "a translation of the original files".  I still have the "original" short (less than 2 minute) recordings on my Toppy. By "original" I mean that I created them by playing each original 1 hour program and pressed the record button on my remote to make a copy of some sections that had a problem. Would that be of help?

I will try to watch live this weekend and the try the experiment you suggest.

 

[pi314]

I was flicking thru the channels last night and noticed the following

http://www.filedropper.com/j3_1

It shows a horizontal pan as well as a vertical pan. It seems like ever 23 or 24 frames a duplicate frame is inserted. I'm not sure if this is same issue as I was seeing before. It seems to me rather than speeding up 24 fps material to 25fps, they have instead inserted a duplicate frame each second. It looks pretty bad.

This was on Eleven.

Edit: I just checked more carefully and there are 24 unique frames followed by a duplicate frame, another 24 unique frames followed by a duplicate, etc.

Peter, BTW, why do think there might be a difference in live vs recorded viewing? I don't understand why that might occur.

 

Edited February 11, 2017 by pi314

[pi314]

Opps, of course you are talking about viewing live via the tv tuner (rather than viewing live via the Topfield). That makes much more sense now. I'm not sure how I miss read that. I will try this out (but again I will probably have to wait until the weekend).

[pgdownload]

33 minutes ago, pi314 said:

Opps, of course you are talking about viewing live via the tv tuner (rather than viewing live via the Topfield). That makes much more sense now. I'm not sure how I miss read that. I will try this out (but again I will probably have to wait until the weekend).

Good Luck.

Peter Gillespie

[pi314]

Well it looks like my Pioneer Kuro can no longer decode tv broadcasts. Its tuner is only MPEG-2 and scanning for channels does not bring up a single channel.

As this is the only tv I have, it looks like I won't be able to test this out. I'm sort of surprised that no one else has noticed this problem.

Edited February 18, 2017 by pi314

[pgdownload]

I'm pretty sure if MPEG-2 was suddenly discontinued more than you would notice  Its taken 20 years for a MPEG-4 channel to be even broadcast (let alone replace MPEG-2). Over 90% of channels are still broadcast using MPEG-2.

Something is wrong with your reception (as you're not getting any channels). It might be the aerial, the wall plate, the aerial lead to the TV or the tuner in the TV itself.

If its not your reception (i.e. the Kuro tuners have broken) then the problem is easily fixed with any $20-$50 STB (Plug the aerial into the STB and the STB into the Kuro)

But for some reason I suspect you've just stuffed up your reception somehow.

Regards

Peter Gillespie

[pi314]

"I'm sort of surprised that no one else has noticed this problem" was referring to the issues with SBS (and ABC). Regardless, my conclusions were rushed and poorly thought through.

I discovered it was a cable problem and the tv is now decoding the SD channels. I'll do some viewing and report back.

 

 

[Basil1503559642]

23 hours ago, pgdownload said:

I'm pretty sure if MPEG-2 was suddenly discontinued more than you would notice  Its taken 20 years for a MPEG-4 channel to be even broadcast (let alone replace MPEG-2). Over 90% of channels are still broadcast using MPEG-2.

Something is wrong with your reception (as you're not getting any channels). It might be the aerial, the wall plate, the aerial lead to the TV or the tuner in the TV itself.

If its not your reception (i.e. the Kuro tuners have broken) then the problem is easily fixed with any $20-$50 STB (Plug the aerial into the STB and the STB into the Kuro)

But for some reason I suspect you've just stuffed up your reception somehow.

Regards

Peter Gillespie

Not sure with the Toppy 7260 but Kuro Tuners do fail,easy fix as you say,a few minutes to determine problem,a bit longer if you have to work from wallplate to Aerial.Lots of problems at present with cheap splitters,alloy Chinese types,they are corroding inside and failing so worth looking at if you have one in the Roof.

https://arstechnica.com/civis/viewtopic.php?f=10&t=1258301

More like 10 years in Oz with MPEG4,first i heard of it was a Strong Employee around 2007/8 posting that future product will have MPEG4 capable Tuners for the Oz Market,then AlanH took up the Crusade around 2008/9. I think the Industry estimation of the start of MPEG4 Broadcasts at that time was 5 years with another 10-20 years before MPEG2 was phased out so they were only out by a couple of years.

 

Edited February 19, 2017 by Basil

[pi314]

I plan to do some more observation but it looks like messed up frames also appear when using the tv tuner.

Last weekend I noticed about 10 instances in an approximately 1 hour long show, this was using the Topfield, and this weekend I noticed 5 or so instances in another episode of the same program, using the tv tuner. It's probably just chance that the Topfield displayed more problems, ie variability between two different episodes. It's also likely I missed a few in each broadcast, especially when viewing via the tv tuner as I couldn't just skip back to verify a possible problem.