[kwlug-disc] OT:Cable Splitters/Rogers

[unsolicited]

On 14-06-09 01:17 PM, Andrew Kohlsmith (mailing lists account) wrote:
> On Jun 9, 2014, at 12:42 PM, unsolicited <unsolicited at swiz.ca>
> wrote:
>> New standard, like said, thicker, more insulation. I first remember
>> seeing it when satellite service started coming out.
>
> Basically RG59 is specified to have a defined frequency
> response/signal loss characteristic. As long as the cable meets the
> spec it can be called RG59.

True for most anything (standard) I suppose. I forget for sure, but I 
think I remember being irritated at equipment labelled 100 Mbps. Read 
further - half duplex! Grrr.

Seems to me happened on 56 Kbps modems too ... IF the stars were aligned 
and the (provider) modem on the other end cooperated. Let alone pre-spec 
passing and post-spec passing. (CCITT acceptance.)

> RG6 has a more demanding spec (frequency response and loss
> characteristics are defined for a larger range of frequencies). To
> meet that, the dielectric had to be made bigger, which is why the
> cable’s bigger.
>
> Old analog cable TV only had to go to (I think) 50MHz or so (this
> seems ridiculously low to me but my quick googling isn’t proving that
> wrong). Digital cable uses much more of the frequency spectrum so
> much better cabling(RG6) becomes important. Satellites were the first
> guys to really need this kind of bandwidth which is why you found it
> there first.

I thought it was 600 MHz - at least that's what I thought the old 
unidirectional splitters were. Looking further, I think it was 900 MHz. 
The internal TV analog tuners having to have to receive in the right 
frequencies to tune.

https://en.wikipedia.org/wiki/North_American_broadcast_television_frequencies

> At higher frequencies, RG6’s loss is *considerably* lower than
> RG59’s, but interestingly it has *worse* loss characteristics at low
> frequencies than RG59. Channels which occupy the higher frequencies
> will be crappier on a chunk of RG59 than they will be on a similar
> chunk of RG6. Bad crimps, kinked wires, loose/corroded connections
> all play their part as well. Just because a cable or connection looks
> good doesn’t mean it’s good across frequency, which is a tricky
> concept for a lot of people to understand.

Thus the UHF/VHF dichotomy that is always irritating?
(To the end user, it's a channel, whether it's 13 or 14 shouldn't matter 
- to an 'uneducated' user. i.e. They don't care, just make it work and 
let me get on with my day.)

Guess the older you are and the more terrestrial / aerial you grew up 
with, the less irritated you get at such. For them, the distinction is 
'normal'. Vs, what do you mean I can't get channel 456!

> You’re absolutely right: digital signal loss results in
> pixelation/blockiness, especially in fast-moving or quick-changing
> scenes.

Probably has more to do with compression than anything else - thus the 
irritation with Rogers playing loose with the compression and HD vs SD 
at various times of the day. Does news or talk shows or soaps REALLY 
need to be in HD, any time - they're talking heads, I REALLY don't need 
to see that pimple with any more clarity than I do already, vs, say, 
National Geographic! <gripe>

i.e. Presumably a glitch in uncompressed video will be less noticeable / 
long / more quickly recovered from than uncompressed, where the next key 
frame has to be received to recover. (Guess I'm mixing types of issues, 
there. Dropped frames vs few bits reversed in a non-critical place.)

[Not holding my breath for universal colour calibration any time soon. 
Ambient light ... what's that! </gripe>]

> Audio can start to stutter as well. Analog signal loss is
> more “smooth” — you get fuzz/snowy scenes and general degradation.
> Ghosting is almost always the result of poor or missing termination,
> causing the signal to bounce off the unterminated port and arrive at
> your TV slightly later (think echo, it’s the exact same thing).
> Bad/missing termination on digital systems looks exactly like digital
> signal loss: blocking/stuttering/etc.. A quick check is to look at
> all the splitters in the house and make sure that any unconnected
> ports are terminated. Terminators look like regular connectors with
> no wires coming out of them:

Think pipe terminator, looks the same. Really, just connecting internal 
wire with the braid. If you want to see impact, stick a paper clip in. 
(But a terminator will do a much better job. Whether it matters in one's 
environment ... YMMV. But if you terminators, use them.)

> http://www.cp-electronics.com/image_lg/PVFT1.jpg. Every unconnected
> splitter port should have one, but the better solution is to use
> splitters with fewer ports/reduce the number of splitters
> altogether.
>
> I only had about 15 feet of coax between the outside demarc and my
> cable modem. Replacing that with a decent quality RG6 with waterproof
> connectors and making sure there were no tight bends or strain on the
> wire gave me 4dB of additional margin on my cable signal across all
> frequencies it was interested in. YMMV of course, but it’s worth
> taking a good look at everything. Every connection, no matter how
> solid, eats into your margin. A good (if conservative) rule of thumb
> is to assume a 1dB or so loss for every “break” in the cable.

Cool! Good to know! Never looked at that segment for bends. Connectors 
are inside the Roger's box outside my exterior wall, and inside the 
house. Hadn't thought of waterproof connectors. Guess humidity would 
have some role in the connector in the Rogers box. (But then they would 
probably throw a hissy fit if I changed connectors at that end!)

> Splitters usually list how much loss they have at each port, and add
> another 1dB for the actual connection itself.
>
> It doesn’t sound like much, but remember that 3dB is a halving of the
> original signal level. When Khalid mentioned that newer boxes are
> very sensitive he means that they’re able to lock on and recover
> signals that’ve been attenuated to hell through poor cable plant,
> lots of connectors/splitters/staples/etc.. Receiver sensitivity is a
> very important metric in my opinion. Same with noise figure (NF) when
> it comes to amplifiers. A lot of people get into ATSC and buy the
> cheapest, strongest “low noise” amplifier they can find, thinking
> that the 40dB gain it gives will help, but forget to look at the NF
> and don’t realize that their strong amp is adding a good 5dB of noise
> to the signal they’re trying to pick up. (/aside)

Good aside. Your prior messages on this (aerials?) made me more aware / 
sensitive to such things - thanks for being here and your posts. Always 
good food for thought.

> Another aside: A friend just had a new Rogers install. The guy must
> have used Thor’s staple gun; ALL of his brand new cable was squished
> to almost half its diameter at every staple. So much for Rogers
> expert installers!

Nah - they've been given no reason to care. And they farm it all out 
(this area?) to independent contractors. Just because they drive a 
Roger's truck, doesn't mean they're not independents.

Perhaps the squishiness is because they're all former Bell guys, and 
crimping quad or hex didn't matter (to them) then, either.

What makes no sense, or even worse, is when they do it to ethernet. I 
have a separate staple gun that uses insulated staples. Don't see why 
they don't use that for all cable, except it's one more tool to lose and 
separate staple type to stock and keep track of.

If someone carries tools, it's astonishing what they spend in replacing 
tools they left at a site!

<sigh>