PC Tech Thread

Cheers and @brun

So far as I understand the hdmi to ethernet converter doesn't change the signal at all so it needs to be a dedicated cat6 cable. I was hoping to find some way round that.

There are also coax cables to every room (although weirdly no aerial), I wonder whether I can do anything with those?

Usb switch for the keyboard/mouse and use the monitor input select for the picture?

I vaguely looked at this and then just bought a separate HDMI switch for about a tenner. A little more button pressing but much cheaper.

I think you can send hdmi over coax, but at not such long lengths as HDMI. Something like these

The guy I did mine with said that coax is laggier than ethernet.

• @aggi
  
  

Yes, both of these are certainly an option, I also found MST hub which allow me to run 3 monitors off one DP input, so wondering if I could combine one of those with a simple cheaper kvm switch.

The guy I did mine with said that coax is laggier than ethernet

Don't make me quote velocity factor figures at you :p

https://en.m.wikipedia.org/wiki/Velocity_factor

Fire away!

I have no idea how it all works, its magic to me! All I know is that I have 3 x sky boxes in my loft, and they run 6 x TVs flawlessly, with the only negative being that I can't use the bluetooth remote controls.

Velocity factor is the speed that a signal can pass through a cable in relation to the speed of light in a vaccum. Coax cable tends to have a vf of between 0.6 and 0.9 depending on various quality factors. Most used in houses tends to be closer to 0.6, which is pretty much the same as good cat 5 and cat 6 twisted pair ethernet.

Even if ethernet was closer to a 0.9 vf, that 0.3 of the speed of light won't make a difference to your viewing experience.

So, with apologies for being a massive pedant (and cunt), the coax or ethernet decision won't create a bottleneck. There maybe other factors that affect latency or transmission rate between the two mediums but the cable itself won't make a measurable difference.

Why not just remote access from one to the other? Do they really lock up to the extent you can't run VNC/similar server/client?

Interesting!

The lag he was talking about was, when you pressed a button on the remote there is a noticeable lag before an action happened, whereas with the hdmi over ethernet there is zero lag, so may well be something to do with the kit used rather than the cables themself.

Sounds likely. Just being a pedant.

Having to do a lot of velocity factor calculations for a phased antenna array I'm making to receive weather satelite signals. Nerds going to nerd.

yeah, they slow it right down! and these aren't cheap nasty desktops either, i'm running fairly decent processor (Ryzen 9 3950x) and 64gb of Ram....

I'm all for nerdery. There is a reason I have over 50 ethernet ports spread around my house.

Hollowcore fibre for the win :-)

Thanks (and @aggi too), I hadn't seen that, so will investigate. It's a present for my kids for good exam results, etc. (not that I won't have a go myself!), so would need it before October.

Hollowcore fibre for the win :-)

Hollowcore/PCF fiber is awesome for bandwidth and being low loss but it actually has a lower vf than copper. Would only matter if you're running it from here to Mars though probably :D

To be honest it sounds like your application is out of control. It's not some enormous Excel VBA financial model is it? I've not seen KVMs used for years, just VNC/RDP, etc.

Can you restrict it so it's not running on all cores?

Its a very niche bit of software which has an excel front end, and god knows what in the back end, but it does very complex, large econometric models (and a bit of bayesian modelling and machine learning), so one thing I can't do is play around with that! I could probably restrict it's usage, but that would I guess slow the process down further...

excel front end

Good guess.

To be honest it sounds terribly designed. If it saturates all 16 cores / 32 threads to the extent remote desktop doesn't work, it is out of control.

oh yes, sure it is, but seeing as it was built by one guy, who is now in his eighties, and lives in France, not much I can do!

OK, good luck with KVM switch solution then ;-)

Ha! yes, it's one of those scary things really, our whole business is basically built on this bit of software, we have replicated everything it does in R, but it is much clunkier to do so, so we plod along using it and hope it doesn't fall over!

Even Gigabit Ethernet doesn't have the bandwidth to support HDMI once you get to HD quality levels:-

1920 * 1080 * 24bits * 60Hz = 3Gbps

That's why the HDMI over Cat5 stuff takes over the entire cable.

There are also coax cables to every room (although weirdly no aerial)

Most TV boxes (Sky, BT TV, etc) will send the current output over a specific channel on the coax so it can be watched in different rooms by a normal telly. Modern houses are usually wired with this in mind. (You don't need an aerial but the TV boxes will also take an aerial in and add the currently watched channel to the signal so the other tellys get to watch terrestrial/freeview channels or whatever the Sky/BT-TV box is watching).

Cheers, that's much cheaper than the HDMI over coax one I found. Only does 1080p though, will have to ponder how important that is but it's certainly an option if there isn't an ethernet solution.

No probs.

No idea if they have a solution, but we use Technomate stuff for our HDMI solution. We have 2 sets of 1 to 1s and one set of 1 to 4 as well, and both work perfectly.
The only issue we found was that the IR signal being sent over HDMI struggled to get sky boxes out of eco standby so had to fiddle with settings, but not sure if other boxes have this issue.