I have heard that its possible to carry two signals through a single Ethernet cable.

eg

phone line >> router >>> two Ethernet cables >> splitter >> one Ethernet cable >> splitter >>> two cables each to a separate device

Would this work?

Anyone have any experience of this? Is there any noticeable degradation of performance?

I would have one device connected which would have access to the net the other however would just be connected to my home LAN

Yes you can do this although it's not recommended.

Ethernet uses only two of the four pairs in your UTP cable so you can squeeze two into one.

BUT

The standard connection uses the blue pair as a ground. Whilst the balanced ethernet signals don't need it to work, it prevents large common-mode voltages being developed between the devices. The large voltages can lead to malfunction or damage.

Running a two-wire phone line up the UTP along with ethernet (and maintaining the ground) is quite common practice.

If you need multiple devices at the far end of an ethernet cable, invest in a cheap hub / switch

The standard connection uses the blue pair as a ground. Whilst the balanced ethernet signals don't need it to work, it prevents large common-mode voltages being developed between the devices. The large voltages can lead to malfunction or damage.

Are you referring to STP? UTP is differential transformer isolated pairs designed for high CMRR. Grounding can be a major issue for ground loops on long distances. Example Ethernet IC connection.

I agree, a few hundred baht to get a 4-5 port switch is a guaranteed way of not having a problem.

The standard connection uses the blue pair as a ground. Whilst the balanced ethernet signals don't need it to work, it prevents large common-mode voltages being developed between the devices. The large voltages can lead to malfunction or damage.

Are you referring to STP? UTP is differential transformer isolated pairs designed for high CMRR. Grounding can be a major issue for ground loops on long distances. Example Ethernet IC connection.

I agree, a few hundred baht to get a 4-5 port switch is a guaranteed way of not having a problem.

Actually you're right Tywais, IIRC aeons ago our 10baseT devices grounded blue at both ends, and we did get loop issues.

Why

phone line >> router >>> two Ethernet cables >> splitter >> one Ethernet cable >> splitter >>> two cables each to a separate device

when you can do

phone line >> router >>> one Ethernet cable >> hub >>> two cables each to a separate device

or even

phone line >> router >>> two cables each to a separate device

Martin

The reason for wanting to avoid using two cables from the router is that I have an ethernet cable running through the floor from the router in my office, to my living room downstairs through the wall cavity

I don't think I'll be able to easily fit another cable through the wall cavity.. well I probably could, but it'll be a pig of a job which I'd prefer to avoid if feasible.

It looks like a hub is the way forward and thanks to all for the valuable advice, much appreciated. (I now know what hubs are for)

RJ45 4 pair cable. 10Base-T and 100Base-T

Pin number

1 data tx

2 data tx

3 data rx

4 not connected

5 not connected

6 data rx

7 not connected

8 not connected

Pins 4 and 5 blue and blue/white pair is reserved for voice and fax services.

So you can have a splitter for data and telephone services or 2 data using pairs 4/5 and 3/6.

one splitter at each end.

With 100Base-T4 uses all 4 pairs for data.

The reason for wanting to avoid using two cables from the router is that I have an ethernet cable running through the floor from the router in my office, to my living room downstairs through the wall cavity

I don't think I'll be able to easily fit another cable through the wall cavity.. well I probably could, but it'll be a pig of a job which I'd prefer to avoid if feasible.

It looks like a hub is the way forward and thanks to all for the valuable advice, much appreciated. (I now know what hubs are for)

Tie the new cable you want to use to the ethernet cable and pull it through the cavity, or first try it with a rope, than tie the cable(s) you want/need to the rope and pull them through the cavity.

Maybe it is possible??

A 4 port hub should do the job for you. Splitters are ideal if one wants to run 2 telephones or fax machines over a 4 pair Ethernet cable.

So, I picked up a wifi repeater and router and set it up in repeater mode with the same SSID and Passkey as the main ADSL wifi router upstairs (using WPA 2 and AES security), both sharing the same channel, which I chose after a survey determined that the channel wasn't being used by any other networks nearby.

I was previously able to connect to the router upstairs but the signal was weak, hence this exercise. However, for some reason now I can not get an IP address from this extended network.

My phone 'sees' the network and the correct SSID, but can not connect to it.

Its driving me nuts, any clues on where to start trouble shooting?

Never mind I sorted it, I am using it as an access point instead. Its connected to my ethernet cable and provides a second wireless access point. It does the same thing with better signal strength and gives me more options for wired LAN connections if I need them (Im looking at you Internet connected LED TV's!)

the only thing that sucks is having to change wifi points when I go upstairs.