Wikipedia:Reference desk/Archives/Computing/2019 July 22

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July 22

Output management

On the French wikipedia, we're wondering about Enterprise Output Management, whereas I only know Document management system. Has anyone ever heard about that ? Regards, Comte0 (talk) 14:21, 22 July 2019 (UTC)

Can Ethernet cables be used with video baluns to transfer TV signal?

Analog cameras are designed to transfer signal via coaxial cables. It is common to see people use video baluns to convert the signal back and forth to be transferred using Ethernet cables for ease of installation and cost efficiency. Now I am thinking of TV signal (from outdoor antennas), which is normally transferred using coaxial cables. Will it work if I replace the cables with balun + Ethernet ones? And is there any disadvantages? My run is less than 50 meters. -- Livy (talk) 18:39, 22 July 2019 (UTC)

Sounds of little value to me. Any time you convert the signal to another form you will add noise. What you might want to do is boost the signal at the antenna using a powered amplifier. That will help to prevent the signal from degrading over the 50 meters of coax cable from the antenna. They are inexpensive. SinisterLefty (talk) 03:00, 23 July 2019 (UTC)

Nope it is not for saving several cents. The problem I am facing is running several cables inside a single conduit. I want to combine a TV signal, an analog camera, and a 100mbps connection into a single Cat6 cable. What I am not really sure is the difference between video balun and TV signal balun. As far as I know the video balun convert the signal from 75 to 100 ohm, and the TV balun from 450 to 75. I don't really understand what they mean. :( -- Livy (talk) 07:32, 23 July 2019 (UTC)

The impedance of a pair in a cat 6 cable is 100 Ohms. For the normal TV coax it is 75 Ohms, and the twinline antenna cable is 300 Ohms. However the ethernet cable is not rated for the TV signal frequencies, so it will be a bit lossy. Also if you try to send another data signals through the cable it will interfere with the TV signal, as that is much stronger. If your balun has the unbalanced part for 75 Ohms, and balanced for 100 Ohms, then it will be a match for on pair in the cable. But a "video" balun might only be rated for baseband video, less than 10 MHz, not VHF from 100-500 MHz. There are products that will do what you want eg here: https://www.radioparts.com.au/Product/00760500/cat01-4-way-rf-over-cat5-amplifier-kingray Graeme Bartlett (talk) 08:08, 23 July 2019 (UTC)

• Yes, this is pretty common. There's a substantial overlap in time between commercial office buildings gaining substantial Cat5 structured wiring, even these builidngs then switching largely to WiFi and producing spare cable, an increase in demand for cheap analogue security cameras and before the contemporary switch to digital video. So for those cameras, baluns over Cat5 are widespread, and still are. For one thing, Cat5 is easier to cable than co-ax – it's easier to pull into place and is more tolerant of tight bend radii.

Is it used for broadcast quality? No. Even for commercial video broadcast (conferencing etc.) you might notice a quality difference. This can depend on the cabling and jointing quality though.

Would I use it for domestic broadcast reception? Probably not. I might do it to put a small screen into a spare bedroom etc., but if I'd invested substantially in some sort of home cinema, I wouldn't compromise that by routing its video over this route. And if I were tempted to, I'd be looking at the highest quality baluns I could, not the security camera cheapies. Andy Dingley (talk) 09:17, 23 July 2019 (UTC)

OTOH, even for terrestrial broadcast a lot of the world is moving or has moved to digital. Digital broadcasts mostly either works or doesn't work. You can have things like certain channels not working or it not working in poor weather, but the effect on quality is generally going to be close to zero. According to List of digital television deployments by country#Vietnam, at least one area in Vietnam where I believe the OP is from has complete analog switchoff in 2015. I'm not sure what things are like now, but if the OP only cares about digital broadcasts then it's likely to mostly be a case of "does it work?". (Noting that even if their area still has analog transmission, if they don't need it then it doesn't matter to them) The compromise if it does is going to be small except perhaps the possibility future changes in broadcast frequencies, future changes in signal strength or signal strength requirements or something ekse will mean what works now will no longer work in the future. Nil Einne (talk) 14:59, 25 July 2019 (UTC)

Digital TV can break up and freeze up when the signal strength is low. SinisterLefty (talk) 16:13, 25 July 2019 (UTC)

Wrong measurement. It breaks up when the error rate increases. Now that might be caused by a particularly weak signal (although that's a signal which could be completely unusable for analogue), but it's more likely to be caused by external noise. In this case that's more likely to be crosstalk from adjacent cables.

But then no-one here is talking about using a balun to put a digital TV signal (which isn't the same as the signal from an IP-based digital camera) over Cat5. Andy Dingley (talk) 16:39, 25 July 2019 (UTC)

My experience with the digital switch-over was that weak analog signals, which were viewable but with lots of "snow", became completely unviewable under digital. I even got a far more impressive antenna to replace my old rabbit ears, but it didn't bring those lost channels back. SinisterLefty (talk) 17:14, 25 July 2019 (UTC)

Read a PostScript file in Windows

How can you read a PostScript file in Windows? I used to use GSView, but I just tried it and it didn't work. I found its website, which says that it has reached it end of life. I downloaded Ghostscript, but when I try to open the file, that isn't one of the options to open the file. Bubba73 ^{You talkin' to me?} 22:25, 22 July 2019 (UTC)

GSView requires Ghostscript. Ruslik_Zero 18:34, 24 July 2019 (UTC)

You can use ghostscript to turn it into a PDF file. 93.136.81.26 (talk) 23:24, 24 July 2019 (UTC)

Thanks. I got GSView working again. It seems that my default program for .ps got changed and I wasn't actually pulling up GSView. Bubba73 ^{You talkin' to me?} 01:54, 25 July 2019 (UTC)

Computer prediction of date and time

Is there a computer program that will take a series of seemingly random dates and times, and predict what the next date and time in the series will be? I'm looking for something accessible to the public, and easily usable by a non tech savvy user. --Puzzledvegetable|💬|📧|📜 23:48, 22 July 2019 (UTC)

If they are random, then there is no way to predict the next one. You could calculate the average time between the events, and add that to the last one to "predict" the next one, but that really tells you nothing. The next one could be 1 second later or a year later. Bubba73 ^{You talkin' to me?} 00:41, 23 July 2019 (UTC)

If it is a Poisson point process, the Poisson distribution can give you some probabilities on ranges where the next one occurs. Bubba73 ^{You talkin' to me?} 05:56, 23 July 2019 (UTC)

Random by definition means unpredictable. However this sounds like an XY problem. 93.136.122.90 (talk) 03:29, 23 July 2019 (UTC)

Well the questioner did say "seemingly" random, which I take to mean there is a pattern but it's not immediately obvious. So is there a program that could crunch the numbers and find that pattern?--Shantavira|^{feed me} 09:09, 23 July 2019 (UTC)

Since "Puzzle" is in your name, I'm guessing this is a thought puzzle you are trying to solve. Could be difficult to do with a computer program, then, as it may involve some human activity, like dates and times of opening Olympic ceremonies, or something astronomical, like dates and times of meteor showers. The computer wouldn't know about those events, unless it's quite an impressive program and database. SinisterLefty (talk) 10:15, 23 July 2019 (UTC)

There are at least three different processes that lead to semi-random appearance. First, the events can be random according to some distribution. You can try to find that distribution and estimate the parameters, but the best you can get is an expected value. Secondly, the events may follow a very regular pattern, but you only observe a subset. Consider a lighthouse that you observe through a busy highway - the lighthouse is using a regular pattern, but random lorries hide some of them. In that case, you can try to find the original pattern, maybe with something like a Fourier analysis. And thirdly, there may be a complex underlying process that guides the events. In general, it will be impossible to deduce that process, but for some classes it is possible. Machine learning, in particular recurrent neural networks like LSTMs might be able to predict new events. --Stephan Schulz (talk) 11:37, 23 July 2019 (UTC)

Apparently I did not give enough information in the question. It obviously needs more context. The Elia sculpture has a computer that decides when to shoot out a burst of flame. A list of dates and times of past eruptions is available on the official website. My question boils down to whether or not there is a pattern in the seemingly random numbers, and whether a computer can be used to determine when the next eruption will occur. --Puzzledvegetable|💬|📧|📜 14:49, 23 July 2019 (UTC)

That would be problem number 3 (arguably combined with number 2 - the eruptions are cancelled (or delayed?) if the weather is bad or there are persons too close to the sculpture). This can be abstracted as predicting the next number from a sequence of known numbers (where each number either is seconds from an arbitrary start time, or the time from one firing to the next) - or, equivalently, to predict a computable function from an initial segment. This is a well-studied case in Computational learning theory. As I said above, in general, this is impossible (as there is an infinite number of possible functions can continue any given finite sequence). But there are, of course, infinite subsets for which this is possible (the most funny one being a function that spits out the Goedel number of its own algorithm as the first number). --Stephan Schulz (talk) 17:50, 23 July 2019 (UTC)