Have an issue with cable DVR that seems to lock up every evening around 7pm but functions fine the rest of the time. I'd wondering if cable DVRs function like cable modems and require signal to be within a certain range?

Some systems require boxes to communicate with the head end servers. Anyone know how current DVRs work? Not once they get signal but how they interact with the system's servers?

Alan

Well, they are dual tuners. They would need more signal.

7pm sounds like everyone is home in the neighborhood using their cable modems for Internet. You need to check connections and splitters and if all okay then add an amplier to the CATV feed...

That well could be part of the problem.

Curious that it happens at the same time each evening. Me, I don't believe internet usage would/could be the cause, other than possibly any on demand where a signal needs to be sent upstream. And I think even that is highly doubtful...



1. How many other TV's are on the same demarc?

2. Any downstream splitters?

3. Last time the cable fittings have been checked (corrosion, dirt, etc, etc)?

4. Has the cable company checked the signal strength at the demarc?

What do you mean by "lock up"? I've never known low signal to actually cause one to crash - just glitch. At any rate, the cable company should be able to tell you (or the homeowner) if the signal strength is acceptable or marginal.

Cable company has come to the house and pronounced the signal to be fine.

I am getting the story 3rd hand--from owner to his house man and then me. It may well be pixelating. But there are 5 boxes--2 DVRs and 3 cable boxes --and the issue is only with the DVRs.

I'm told each is homerun from the same splitter. I suppose I am asking if cable box signal is affected by cable modem use. I understand that bandwidth will drop with incrased demand. But there are a fixed number of homes for each run--this is how MSOs set up their infrastructure, typically 1:25 homes.

If it were rusted fittings or a bad ground why the same tim each evening? If cable boxes and modems share the same bandwidth and 7pm is peak usage is it possible that DVRs require more signal to display its picture?

Yeah, please describe "lock up." That could mean a lot of things --
picture freezes
menu's on, won't change
unit won't respond to remote
unit won't respond to remote or front panel push buttons

Okay, there are two tuners. A manufacturer would be aware of that and would (very likely) provide amplification before splitting the cable signal.

You're right that the boxes interact with the headend, both for initial authorization and for maintaining connection. I'd guess that a 7:00 PM ---

Did you say exactly 7:00 PM, or is it approximately 7:00 PM?

...did you say that a 7:00 PM freeze-up might be... never mind. If it was caused by lack of return signal, the result would be an unauthorized box, so you'd lose programming and get a notice that you don't have programming.

I once had a client who found, after several days of troubleshooting, that a PAR lamp made an audible buzz and also killed his UHF channel 17 when it was on. It came on in the early evening in the garden right outside the room where the antenna system was, and we modulated a satellite output on UHF 17. I take from this case that some other thing that comes on at 7:00 PM might be a source of interference that messes with the box.

Lastly, what happened when you moved that box to another location and put a different box where it is now? You're an excellent troubleshooter and surely thought of this.

Great point on interference. I missed that one.

IF it's only one DVR, out of several in the same system locking up, that changes things.

I'd start with a move to see if the problem follows the box.

That question's perfect logic suggests the answer: it's not the fittings. A question's bewildered "how can it be" should lead one to strongly consider "it ain't."


I wrote the following paragraphs before I realized that the answer is also in the question's "if" assertion. Cable boxes and modems do not share the same bandwidth. The two services together cover a large bandwidth and it could be said that they share that, but each is in its own separate range. It's similar to saying that bass guitars and piccolos, both reproduced by audio systems, share the same bandwidth. It's not hard to make filters that separate or combine bandwidth segments with almost no loss; see the satellite diplexers we used for years and years. Oh, yes: and loudspeaker crossovers.

The question is similar to asking whether bass reproduction in a speaker system is going to encounter problems when playing a recording if, suddenly, many piccolos are in the music. Internet and TV channels are on different frequencies, so use or overuse of one should not affect the other.

(I stated it that way because piccolo music might suffer if suddenly lots of bass played, but that would be due to an overload of the audio power amp, a circumstance that won't occur with cable amps.)

It is only the 2 DVRs. The 3 cable boxes remain unaffected. It's only at 7pm and otherwise the signal at those locations remains within specification.

An aside: with digital cable the head end no longer sends every channel down the pipe. It's all data now. There is no difference between the data from a cable modem and data for a TV channel save the amount. Clearly, an HD channel requires more data to be sent than a SD channel. But why would the dvrs show issues and the HD cable boxes evince none. Hence my quarry for how DVRs work in a MSO system.

They work perfectly fine all of the time save the 7pm time period. I will need to find out if they pixelate or freeze. However, given that the DVRs work all of the time save at this hour it does suggest they suffer from the same bandwidth issues as cable modem. But is it?

And, as I suggested before, you've moved components around so that you know it's not the actual location that's the problem? It does not seem likely that the same problem with the two DVRs is a coincidence, but it also does not seem likely that the same problem with two locations is a coincidence. The universe must be divided by moving some boxes.


I was not aware of that. I'm also not convinced. A client has a six year old JVC that he can connect to the cable without a cable card, switch to digital "tuner," and then "tune" lots and lots of channels. The channels don't show up with the expected channel numbers, which seems to me to be just a matter of mapping, but the "tuner" seems to "tune." This is without a cable card -- how could this be if the digital channels were not modulated on particular frequencies, but were just data?

In addition, such a system would have to be capable of sending out data for all channels simultaneously, because a neighborhood of 2,000 sets just might tune in all channels (theory). Let's say there are 200 channels, and that the channels can be set up via compression so that three separate programs could be modulated at one frequency. Then, a tuner that could tune 67 channels -- easy peasy -- could handle all 200 programs. But a data system that would have to pass 200 programs as data on one channel?


You start by making a statement about HD and SD bandwidth (more or less) but then ask a question about two types of (presumably) HD boxes. If those two sentences are related, I don't see it.


Query.


7:00 PM -- exactly ?? -- until when? They must stop at some time. Is it always the same? It took two weeks to pin down that PAR lamp that caused problems, and we did it by narrowing down the parameters.


That would have been nice to do before you said "lock up" to us.


Why? Are you saying that during the same time period the internet is slower? Run speed tests at several hours of the day. Pin down the stopping time of the DVR problem.

This is really a pain, I'm sure, mostly because it happens way after you want to be there troubleshooting. Best of luck.

Here's what feeds us from most major MSO's- [Link: harmonicinc.com]

Ask 7 different techs from your system whether or not you should amp the return path or keep it passive. Trust the majority of replys. Terminate unused ports on splitters and properly select amplification based on the loss introduced by all splitters in the system and cable lenghts. I found this geeky site to be informative- [Link: swhowto.com]

I like the skype idea, let them show you the 7pm crunch.

I think that pinning down just how regular and how close it is to 7 PM, and when it stops being a problem, will make the source of the problem either really obvious, or will reveal it to be something completely squirrely, incomprehensible and unforeseeable, like that PAR lamp illuminating a garden that somehow was able to take out UHF 17!

I liked your second link and saved it to my favorites.