Not bunk at all.
A cable operator sets up signal levels to be reliable at the wall socket + 10m of good quality cable.

The longer the cable, the more the signal is degraded.
At >10m of (cheap high-loss unknown quality) customer cable, the signal level becomes an unknown factor.
It may be OK
It may be totally crap.

That's why the cable operators always say: use max 10m good quality cable from wall socket to TV. Anything else, and they can go on wild goose chases trying to find the problems when the whole time it was caused by cheap poor quality customer cable.

The names of the channels are stored in the box / TV from the last successful channel scan.

If the signal is currently lost, then the name will appear but signal will be lost.

There are many easy ways to tell if the cablecom signal is good or bad:
Do you get the unencrypted Welcome channel? This is broadcast on one of the lowest frequencies, is not encrypted (doens't require a DigiCard or Settop box) and thus is one of the easiest channels for your TV to receive.

No Welcome channel = poor / no signal.

See my note re coax lengths. The 10m statement is 100% correct.
>10m, and there is no guarantee that the signal level will be good enough.

It may work, but it will not be guaranteed.

I researched this (again) , nothing found to back that 10m claim up. Do you have a reference / site / link for us that will back up the claim ?

I have worked in the cable TV industry for a number of years and have 30 years experience in telecommunications, radio and TV industries, always in the technical field.
Right down from running those blasted coax cables, fitting the connectors, and measuring the performance, through fitting police radios to motorbikes, fitting autopilot systems to ships, up to replacing satellite communications antennas and working on high power shortwave radio transmitters. I know how coax performs. I know about signal levels, frequency response, and transmission of RF signals through a coaxial medium.

I consider that sufficient reference for myself.

You are free to search the internet, but not all aspects of common technical sense are published on Wikipedia sites!!

But hey, I googled "cablecom 10m koax" for you and the 2nd entry was someone stating the same thing from cablecom: max 10m coax is what they state.

Convinced?

Crap. You guys are right to disbelieve me. I am totally wrong.

Cablecom recommend maximum 5m cable length, not 10.

Here's the words from the horses mouth:

Length of tv cable
In the interests of signal quality, we recommend that you use an antenna cable that is maximally five metres long (from the socket). We also advise you if possible not to bend or otherwise damage the cable as this will additionally impair signal quality.

Should you use a longer cable, please note that increasing cable lengths may result in signal loss, and in turn picture and sound faults. In order to avoid this, you can order an additional socket from our customer service.

http://support-en.upc-cablecom.ch/ap.../222/related/1

For what it's worth. Got a cablecom mediabox HD yesterday morning. Seemed ok after the install. However, when I put the music on I was hearing frequent dropouts. Replaced cable between wall adaptor and box. Problem gone, bad cable. Got to say never saw cables this thin before. Much thinner than any I had in the US. Based on the "thinness" I'd say keep the lengths as short as possible.

So, nothing concrete from any reliable source then ?
In fact, most Google hits will back up my claim about 100 feet. If you do the Math and the Science, calculating the attenuation over different CoAx lengths and types , none of them will get you anywhere near 5M/10M.

The cable company works on about 100dBuV at the house distribution point. By the time that has reached the wall connector wall connector the signal could easily have dropped 10dB to 90dBuV, depending on the layout of the building and the length of cable used.

A modern TV works reliable with about 60dBuV signal level input
Ideally, you want to keep the signal level at the TV between 60dBuV and 100dBuV

Given that the cable signals operate from around 20MHz to 860MHz, it is the cable loss at 860MHz that must be considered.
Why should we consider 860MHz?
Well, some cable companies, including cablecom, actually operate their DVB-C carriers right up to 860MHz!!
Indeed, in the Zurich area, the 2 new ORF 1 HD and ORF 2 HD channels are actually both on the highest frequency DVB-C carrier. At around 800 MHz.

So we must consider the cable loss at 860MHz. Note that most spec sheets quote cable loss at various frequencies, take the 1000MHz figure if no other suitable figure is stated.

Typical cable loss, per 100ft (33m):
RG59/U (common TV cable between TV and wall socket) = 11dB per 100ft at 900MHz (varies a bit by manufacturer)
So for a 10m length an RG59U cable can easily cause 3dB signal loss at 860 MHz

So you loose half your signal power between wall socket and TV set with a 10m RG59/U coax cable.

Add into that equation

• cheap coax with higher loss
• poor connectors
• poor / loose terminations
• loop through connections through other settop boxes (like I do)

and you can easily loose lots of signal on the last 10m

In my house, I have a good quality 15m cable between wall socket and cable settop box, and then another 2m cable from settop box to TV. Longer than specified by cablecom, BUT I selected good quality cable. And I knew my signal levels were good in the first place.

The cable company has to have a rule of thumb that works all the time for all of the installations for all of the customers.
Remember: they specify the network up to the wall socket.
From the wall socket to the TV is a big unknown, outside of the control of the cable company. My friends in the field have told me many stories of poor, damaged, home-made coax connections that kill the signal between wall socket and TV.

That is why the cable co states a 5m or 10m maximum cable length.
That way they can guarantee the signal level at the TV set will be in the ideal range of between 60dBuV and 100dBuV, regardless of cable type the customer has chosen.


Now here's a pratical example I had last week with a US cable company in the USA:
The input signal to the house went into an 8-way splitter, which fed 8 wall sockets.
Only one wall socket had a TV connected.
I wanted to connect a cable modem to a 2nd wall socket.
Result: no cable modem connection. The cable modem would connect sometimes to the downstream, but could not establish an upstream connection.
Even when I disconnected all extra sockets from the 8-way splitter, I did not have enough signal to establish upstream connection
I then disconnected the 8-way splitter and used just a 2-way splitter.
Still not enough signal
So I then removed all splitters in the cellar and patched the cable connection from the street directly to the one wall socket of interest.
At the wall socket, I ran a cable to a splitter, fitted only 6 inches away from the cable modem. The cable modem to splitter connection was thus only 6 inches.
The other output went to the TV set.
Result? Finally enough signal level to allow upstream, downstream, and cable TV operation.

And I was using solid core, semi-flex coax. Much better than the usual flexible coax used for flying leads.

A classic example of how sometimes the signal level at the house is so low that, with enough splitters added, the resulting signal at the cable modem / TV set is actually very borderline.

So, Mr Upthehatters2008, what's your experience with coax and cable TV systems?

My TV is bigger than yours !!!!

wow,you are a expert..

Sorry, your facts and calculations are wrong. Google attenuation calculator and work your own mistakes out. Still not found any engineering sites yet to back your claims up ? Nope, you won't. Yet you found many to back mine up.

Back to the original topic, CoAx is fine up to 100 feet. Under any domestic conditions.

Show me a cable that long that isn't. ...and with reference to the OP, I will put money on his 10m cable and any other 10m cable being just fine for domestic television.

I'll add this in here. I had what I think a definite cable issue, it was just maybe a 3m cable. Replaced it and the radio dropouts went away. I did notice however that I was getting what I think they call a judder in the picture. Not smooth, consistently jumps. I finally had enough and started trying things. Went into the menu and then into network search. I guessed the PIN was 1234. Went into that and ran Automatic Search. Went back to watch TV everything was fine.