DCC Power: Summary

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Summary: This table summarizes some the important points about DCC Power

Some Notes on Digital Command Control
The encoding method for digital data onto the track power employed by command control systems based upon the NMRA Digital Command Control Standard provides a much greater signal-to-noise ratio than methods utilized by many other command control systems. If there is sufficient power to operate a locomotive, there is adequate signal amplitude for operation of a decoder.
The designers for the DCC Standard were aware of the difficulties that users of some command control systems experienced with inadequate wiring. Therefore a number of tests with intentionally bad wiring practices were conducted. If the locomotive could receive sufficient power to operate, the DCC signal was strong enough for reliable operation.
At ≈10KHz, the DCC signal is essentially immune from problems such as reflections and standing-waves, which the higher frequency tone systems can experience. The DCC specification requires that decoders reject signals greater than 100 KHz. All the useful DCC signal information is below 100 KHz, and the behaviour of wiring at frequencies greater than 100 KHz is irrelevant to DCC operation..
Telephone companies and LANs provide data communications at frequencies in excess of 10 MHz over an ordinary unshielded copper twisted-pair wiring.
At frequencies greater than 100 KHz, the controlled impedance and proper termination of transmission lines is far more important than the skin-effect. The impact on conductivity by the skin-effect is insignificant below 100 MHz.
Model railroaders should always provide adequate wiring to minimize voltage loss between power sources and operating locomotives, whether they are using command control or not. Many model railroads do not have adequate wiring. Digital Command Control systems do not require special wiring to work. As with ordinary analog operation, inadequate wiring will cause poor locomotive performance. Since multiple locomotives share the same wiring with DCC, the effect of inadequate wiring includes the slowing of one locomotive when another nearby loco draws current.

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