What Constitutes a "weak signal?"

[JohnJ9]

I have my system "almost" working fine. The only problem I find I still run into is an occasional recording that terminates abruptly due to a "weak signal." In looking at my diagnostics on my ETH6, My SNR is ALWAYS in the 38.3-39.0 range, and the Signal Level is ALWAYS in the -2.1 to -4.0 range. Since any of these sorts of problems are brought on by that Murphy chap, it tends to happen on things that will never be played again: live TV or single showing pieces. An acquaintance of mine is working his first MLB Spring Training, and I knew today's game was going to be televised. I'm happy to say I have the first fifteen minutes of the three hour broadcast. No wait - I'm not happy about that at all.

A check of WMC says that the recording was terminated because of a weak signal. I was sitting and watching the game live on TV at the same time, and there was no signal interruption on the cable side. If there ever is an interruption, my suspicion is that there might be a packet or six missing, but in my heart of hearts I really don't believe there is a signal interruption. I'm wondering what kind of interruptions get interpreted as weak signal, and why the driver layer doesn't lie to the system for a very brief loss until some number of seconds passes before deciding all is really lost. I actually have multiple times watched the Ceton unit continue to stream to a WMC that is no longer listening when this happens. Today, I didn't realize it took place in order to get in and do any diagnostics, but the way I see it (and would have coded it), I'd have the driver layer anticipate that there are hiccups in most any streaming system and somehow find a way to keep the upper layer happy for a bit until I was sure nothing was going to come back. As it was today, my tuner showed the tuner occupied and tuned to the right channel right up to the very second it was supposed to shut off, ten minutes after the scheduled time ended. Some part of the system actually still believes all is well, and even knows enough to turn the tuner off at the appropriate time. Unfortunately, two hours fifty-five minutes of that effort was done for a system that had no intention recording it - for a deviation that was probably milliseconds long - but deemed catastrophic. Somehow, that just doesn't seem right.

[erkotz]

Windows Media Center indicates the signal is less than a pecentage of the expected bitrate. A temporary interruption would trigger this, and could still have good SNR/Signal. You should open a support ticket with us to investigate. You may also want to follow this KB article first, if you have not already: http://support.microsoft.com/kb/2708283

[mldenison]

Thanks for the Microsoft link!

A couple of times a week, and last night, a recording abruptly terminates with a 'weak signal' message. The picture looks fine as it quit recording.

It'll be interesting to see if the issue goes away.

[barnabas1969]

See this thread relating to the Microsoft hotfix that erkotz mentioned:

http://www.thegreenbutton.tv/forums/vie ... f=6&t=2337

[JohnJ9]

The picture on whatever is stored is always perfect when I run into this error as well.

The hotfix didn't apply to me for two reasons: I'm running Windows 8.1 Pro, and the registry setting is already set, either from a suggestion months ago, or because Win8 just sets this - dunno.

I captured the data for a bug report and will turn it in when I get a chance. This is, however, the disappointment that tends to show that these sorts of boxes have their sights on the wrong level of service. I'm one who will likely never get rid of my DVR, but I find that my DVR always works, and the Ceton works most of the time. Until nothing short of perfect is the accepted goal, the sights are too low. Until any list of excuses is unacceptable, the sights are too low. There are more MIPS on the dedicated HTPC, and a dramatic overkill in bandwidth availability in the house. Somehow, that's not enough. There needs to be some resiliency built into the system.

[barnabas1969]

@JohnJ9: I can't say that things were perfect when I had an InfiniTV. However, I will say that my PC (with two HD HomeRun PRIME's (three CableCARD tuners each), and two HD HomeRun "dual's" (two ATSC tuners each)), my system is at least as stable as the DVR that I used to rent from the cable company. Others have the same kind of stability with an InfiniTV.

It's important to understand that signal level/strength and SNR/quality varies from one channel to another, and even at different times of day/year due to outdoor temperature fluctuations and many other factors. Saying that your signal is always X, and your SNR is always Y, doesn't mean much unless you are checking them while the tuner is tuned to the problem channel, very near the time of the problem.

Channels with a higher frequency tend to have lower signal level/SNR than channels with a lower frequency. And... it is possible for higher channel numbers to be assigned to lower frequencies... so channel number is not a reliable indicator.

Have you checked the signal level and SNR on the same channel as the problem, within a few minutes of the problem?

[JohnJ9]

Those readings were during the problem. There's not a lot of variation at all with the box. I check it all the time just out of curiosity.

[JohnW248]

Those readings were during the problem. There's not a lot of variation at all with the box. I check it all the time just out of curiosity.

The "weak signal" message can be triggered by other things. As Eric pointed out, the message comes (like the old magic eight ball) when an expected bit rate is interrupted. Other things can cause this. For example, if the recording drive has an issue, if there is a problem with the network for an instant, and so forth. All these things can cause the same problem without signal being the issue.

So it really takes a bit more sleuthing, After five years or more (started with the ATI DCT tuners on Vista OEM) I have a very stable operation with a mix of both PCIe and Ethernet cableCARD tuners. The only issue I see on occasion is a spat between MC PCs pulling tuners from a Ethernet "pool" with a "no video" on first try before the second place computer gets its second choice tuner.

I'd check network traffic and packet loss when you see the issue as well as any problem with the recording drive. I find recording to a local drive dedicated to Recorded TV provides the best response. Also if you're running a Ethernet tuner, be aware that routers can pose problems as well. The recommended set-up is to have your MC PC and tuners on a switch and not on ports on the router to prevent any router firewall sniffing. And on the MC PC it's best to only run MS Security Essentials and the Windows FW. Third party AVS and FW are know to cause problems on many systems.