Wikipedia:Reference desk/Archives/Computing/2019 April 7

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April 7

Can I use crappy networking equipment with 4K IP camera?

I have a supposedly 4K IP camera connected to my network and when I view the image on my PC and open Windows Resource Monitor, I see a receive rate between ~820-880 KB/s. Does that mean that any old crappy network cabling/equipment will do just fine? Like a 10/100 network switch and Cat 5 cable? I need to waterproof an RJ45 connection so I have to either a) cut the end off a cable and solder it back or b) cut the end off a cable and attach a new RJ45 plug. If I'm right that a crappy connection is okay, then the "impedance bump" of a soldered ethernet cable will be okay, right?

Incidentally, is this rate of data what you'd expect for 4K video (compressed with H.264) at 15 FPS?

Screenshot of Resource Monitor

Thanks 78.149.180.132 (talk) 02:16, 7 April 2019 (UTC)

As a rule of thumb I assume a 10 fold difference between B/s and bps which allows for framing etc. So superficially your 850 kB/s works out at 8.5 Mbs which agrees with the network graph on your screen shot. However there are a number of other factors to consider. If anywhere along the chain you have a poor cable or connection then you may get noise or dropped bits. Not a problem for TCP, it just requests a resend. However a resend more than doubles the bandwidth consumed (send - NACK - resend), so a noisy cable can reduce your bandwidth dramatically. For this reason, if no other, your option (b) is probably better. The "impedance bump" is where you can get reflections which lead to the aforementioned dropped bits and noise.

A 10/100 switch may be adequate if it is just connecting two cable segments together, but some of the cheaper ones cannot handle full speed on all ports. The internal switching just is not up to it. Again, a rule of thumb, assume that a 10/100 domestic switch can handle 100 Mbs total, any more and it may start buffering or dropping packets, which will require a TCP resend with consequent loss of bandwidth.

I've assumed TCP, but if your application/camera use UDP you do not get the resends, the data is just lost and the picture degrades. Martin of Sheffield (talk) 10:11, 7 April 2019 (UTC)

Duplex LC connector with SFP module

Please help I want to know what will I get or should get if place an order of 1 unit 1000Base LX SM mini gigabit transceiver such as D-Link DEM 310GT.It seems from the datasheet that a duplex LC connector should accompany the the main SFP module according to the product description and technical features listing of D-Link DEM 310GT as mentioned in The datasheet link is "http://www.dlink.co.in/pdfs/products/DEM-310GT/DEM-310GT_ds.pdf".Am I wrong?Wrogh456 (talk) 15:17, 7 April 2019 (UTC)

You will get what you see in the bottom left of the picture at the top. It will be a sfp module with a rubber plug. It will have the duplex socket. There will be no fibre optic lead with it. Graeme Bartlett (talk) 21:24, 8 April 2019 (UTC)

Agreed I understand that the item generally comes as you described in this particular case strictly going by the data sheet "http://www.dlink.co.in/pdfs/products/DEM-310GT/DEM-310GT_ds.pdf" in two places first in the header line and then feature and component listing along with other features or components like melt enclosure for lower EMI and in the product description headline it is witten as follows "D-Link Gigabyte Interface converters are are tranceivers that connect..The fiber optic transceivers have standard duplex LC connectors for connection compatibility".Strictly with refrence to this particular make and model is it wrong to expect that D-Link will ship standard duplex LC connector with the SFP module as per the datasheet even if there no SFP patch cable just the loose connector.Is my argument technically flawed.I am agreeing cent percent with your generic version for example in D-Link USA /Australia datasheet it is mentioned that the SFP module has LC type interface option of so no duplex LC connector should expected to be shipped with SFP package in USA/Australia/UK etc as applicable matching with the stipulated technical specs assured in the respective datasheet whereas since in D-Link India datasheet it is described this way hence my question is it technically wrong to expect "standard duplex LC connector" according to D-Link India datasheet product description.Same main product in different countries are known to be shipped with different accompanying free accessories depending of marketing decision by companies.My question is in relation to this particular model and make in India market is it technically wrong to expect the thing called standard duplex LC connector with DEM 310GT — Preceding unsigned comment added by Wrogh456 (talk • contribs) 07:10, 10 April 2019 (UTC)

The connector is the hole in the SFP module. You will not be getting any extra patch lead. As I said you will have to have more information to get a patch lead. It is not "technically" wrong, but different vendors sell different products. If you want a whole working system then you can pay an integrator much more money to put the whole system together, ie a "solution". Graeme Bartlett (talk) 12:17, 10 April 2019 (UTC)

Rear camera does not work after changing motherboard

I had the android phone (Huawei Y5 II) repaired by customer care. After replacing the mother board I came to home and to my surprise, I found that camera is in selfie mode. I tried to switch the rear camera by pressing the "switching" icon. But it does not work. I checked the other options with no results. Did technician forget to assemble properly ? What might be possible cause? Thanks.--103.231.162.134 (talk) 16:05, 7 April 2019 (UTC)

You should ask the technician or the customer care, I think. Ruslik_Zero 18:15, 7 April 2019 (UTC)