[mythtvnz] High quality cables

[Criggie]

Don Robertson wrote, On 13/02/15 13:55:
> Firstly, I found a post in my drafts folder about Kodi - I've given it a go 
> running from a usb stick and it is very cool. Thanks for suggesting it whoever 
> it was all that time ago. I am sticking with Myth for my front end - I like 
> Kodi's Youtube browser but - surprising for a Linux user -  find it does not 
> give me enough control over recording schedules.
>
> Second, I am not a great believer in spending lots of money on high quality 
> cables - and I don't think wifi and emf signals are gong to kill me. Just ruin 
> my spelling.
>
> But. I am moving my Mythbackend machine and my Silicon Dust HD Tuner to 
> another room. I was using an approx 10m cable to connect the Tuner to the 
> arial wall socket. I am now trying to run the same cable through the roof 
> space to the SD Tuner box. But when I do this, I am getting low signal 
> strengths and cannot lock onto some channels.
>
> I have tried running it as far from electrical cables as I can - without much 
> (if any) improvement.
>
> If I run a network cable to the AD Tuner and use the short antenna cable that 
> came with the Silicon Dust tuner, it is fine.
>
> I also notice the Silicon Dust cable is fat, the antenna cables in the roof 
> space and the 10m cable are not as fat as this, but fatter than some other 
> antenna patch cables I have lying around. 
>
> So - would the electrical cabling affect the antenna cable? Is the stuff used to 
> wire up the house of different quality to the stuff used to make the patch 
> cables? And is there any terminology I need to use when trying to find good 
> quality antenna cable? The stuff I have seen does not look all that fat - but 
> as I am always telling my wife, size isn't everything.
>
> I am just wanting to make sure all this stuff works before I go putting in wall 
> sockets and feeding network cable to the front end and so forth. 

Digital cables (hdmi, DVI, Ethernet) should all work fine to their
maximum specified length, which is ~100 metres for ethernet.

Analogue cables (speakers, composite video, VGA) have losses in signal
quality, but these are so small that its really irrelevant.  Bad
connectors or multiple joints have far more of an effect than the
underlying cable.

Power cables (ac or dc) have power losses that increase with length.

Now your problem...
Radio-frequency cables (aerials) are weird... RF signals don't actually
travel through the wire, instead they "spider" their way down the
outside.  And the signals are such low power that length becomes important.

Short answer - short aerial cables work best, use longer ethernet cables
instead.
In theory putting your homerun right inside the roof would best for
signal. 
Or get a competent aerial guy to rerun the whole cable from top to
bottom.  That way there are no joins, which are what really hurt the signal.


-- 
Criggie

http://criggie.org.nz/