Telco Using Ethernet/CAT Cable for Cab Bus/Loconet

I would only explore this topic if you are:

1) building a new layout and want to install a better cab bus using common inexpensive ethernet cables.

2) having problems with the cab bus itself when the trains run. Poor throttle control issues.

Electrical Noise cab bus problems can be addressed buy using ethernet cables which offer many communication benefits such as eliminate crosstalk with other DCC wiring cables. Think of a "poor mans" shielded Cab Bus cable.

If you current cab bus is working just fine, there is NO reason to go out and replace the wiring.

The topics in this section are:

1) The CrossTalk Problem

2) How does this relate to DCC?

3) The Long Cable Run

4) Ethernet Cable Backround Information

5) Advantages and Disadvantages of each type of cable.

6) The Two Ethernet Cable Conversion Options:

6A) NCE's RJ45 UTP Cab/Throttle Panel System using standard RJ45 cables.

6B) Replacing 6-Conductor Telco flat Cable with Cat cable.

7) NCE 6 Conductor to CAT Cable Signal Pair Strategy

8) Digitrax 6 Conductor to CAT Cable Signal Pair Strategy

1) The CrossTalk Problem

In electronics crosstalk (XT) is any phenomenon by which a signals transmitted on one circuit or channel of a cable or wire creates an undesired effect in another cable or wire. Crosstalk is usually caused by undesired capacitive, inductive or conductive coupling from one circuit to the another. In telephone industry, crosstalk is often described as pieces of speech or tones leaking from other people's connections. This was most apparent when the telephone line ran for miles and miles. How would you like other people hear your phone conversations, intentional or not, when you have different phone numbers? One normally expect to have both a private and high quality voice conversation when using the phone.

2) How does this relate to DCC?

On our layout, we have cables and/or wires that carry the DCC track power from the booster to the track. The wires must carry all the noise and power spikes (voltage and current) that occur naturally when running moving engines on rails. Why? The connection via the metal wheel used for electrical pickup between the engine and the rails is intermittent. Uneven rail surfaces can cause the wheel to bounce and lose contact for a brief split second. The more pickup wheels the engine has the better but even then it still not perfect when you factor in dirty track and wheels. You have the short circuit problem which can be momentary through a switch or steady state due to a derailment. The point is that these wires are very electrically noisy.

In contrast, the cab/throttle bus carry information between the throttle/cab and the command station. Reliable communication is paramount if one is to have complete control of the trains the engineer is running. The common "modular telco cable/wire" system is designed to be low cost. But to reach the low cost goal, it comes with the compromise that is must be restricted to being a short distances cable run such such as found between the phone jack in the room to the actual phone itself.

3) The Long Cable Run

As noted in the long phone line crosstalk issue, it was the long run of multiple wires bundled together in a single large cable that created this problem. For a given length of wire(s), the higher the speed the signal waveform gets the more crosstalk you get between the wires. Granted that we do not have miles of wires in our layout, but the problem happens none the less especially when we use high speed signal such as found in digital communication. These type of high speed Digital signal waveforms are found on the DCC signal on both the track and on the cab/throttle bus which means it is much easier to get crosstalk problems between the two. Furthermore, on large layouts, there we run wires over much longer distances than one would find on a small home layout. Together the digital high speed and long bus runs greatly increases the opportunity for the cables to cross-talk to each other.

4) Ethernet Cable Backround Information

The common flat "Telephone cable" is a "communication cable". Communication cable are cables that have features that help with quality signal transmission over a simple wire cable. However flat cable was never intended for long distance runs of signals including telephone. It was intended for indoor use and to go short distances between the telephone wall jack and the actual telephone in the room. An alternative to using flat telephone cable is to use Ethernet cable instead.

Ethernet cable is constructed of 8 wires that form 4 twisted pairs. Each twisted pair consist of only two wires. The twisted pairs are not twisted together with any other twisted pair. All 4 twisted pairs share a common outer case that hold them together. Each twisted pair have unique colors to help identify which of the 4 twisted pair you have. Each twisted pair has a modification of the color pattern to help you identify which wire you have within the pair. All 4 pairs are identical in contstruction, design and performance. So they are interchangeable with each other.

Ethernet cable goes buy names as CAT3, CAT5, CAT5E and CAT6. Reading from left to right, each of these cables designations allows for higher and higher speeds of communication. The cost typically goes up too. CAT stands for CATegory in reference to the ETHERNET standard. For our purpose, any one of these category cables will work.

Ethernet cable is available at most big hardware chain stores and computer stores. It comes in a box for long cable runs or in pre-made lengths something like 8, 16, 25, 50 or 100FT.

5) Advantages and Disadvantages of each type of cable.

Ethernet Cable advantages relative to Flat Telco Cable

1) Larger wire gauge mean less voltage drop in the cable for a given length of cable.

2) Twisted signal lines means:

2a) High quality signal integrity.

2b) High noise rejection both in pickup and transmission.

Ethernet Cable disadvantages relative to Flat Telco Cable

1) It will requires you to make a custom cable. There are no pre-made cables with the right connectors installed available. Note: Having the right tools is critical to making a reliable cable. For more information on how to make a reliable cables go here: Telco Making cables

2) The cable will cost a little more than the Flat cable on a per foot bases. However it is a lot cheaper than using other multi-conductor communication cable options.

6) Ethernet Cable Conversion Options

There are two ways to integrate Ethernet Cable to be your cab bus /loconet bus.

1) Install NCE's new RJ45 UTP Throttle/Cab panels. Plug and Play method.

2) Replace the existing 6-Conductor Cable. This is low cost Do It Yourself (DIY) method.

Each method is discussed below.

6A) NCE's RJ45 UTP Cab/Throttle Panel System using standard RJ45 cables.