Explains DCC and its applications, Power type NMRA standards and provides insight on DCC Controllers and Decoders (Buy DCC Decoders)
Digital Command Control (DCC) or to simply put it a digital remote controller (see pictures below) is a system used to control a digital model railroad. These controllers can be used with trains fitted with on board Decoder electronic circuit which accept commands from the controller.
Few functions that a controller can perform are control Start/ Stop /Speed of the train (very basic), Control multiple locos and their speeds on a single layout at the same time (a key benefit/feature of DCC). Advance functions can be, control sound and light functions of a loco. The controllers can do more than this but this information is good for start.
The command controller consist of a main power supply/ a digial controller and optionally a power booster. It is the communication centre for the layout. It supplies power to the rails via the feeders. Power is always supplied to the rail unless we shut down the system or isolate a block or section of track from the booster.
Type of Power
DCC uses a modulated form of Alternating Current (AC) typically 16 to 22 volts max. The command controller generates this thru the built-in circuitry. The standards for these are governed by the NMRA organization.
NMRA refers to the DCC output as a DC waveform.
Understanding the Signal Aspect
Referring to the modulated signal that the command controller sends out across the track is both, a "power source" and a "means to transmit data". The power is actually carrying a digital signal across it. This signal is decoded by the onboard chip or circuit on the Engine.
This is the point where the signalling aspect comes into play. We all understand that a digital signal is 1's and 0's formulated in a format known as binary (00010011).
Inserting data onto a power line and creating a signal system is basically what DCC is.
The decoder which is fitted on the engine (Loco) receives the modulated signal from the tracks thru the wheels. The first function of the decoder is to generate a pure DC signal to power the itself and the second function is to separate the digital signals embedded into the modulated signal and use it to operate the loco. These digital signals carry information for the engine (Loco) operations (start/stop/speed and others as explained).
Putting it together
The Command controller or the digital remote sends a modulated AC power to the track.
This data is interpreted by the Decoder on the Loco.
Lights/ Sound (sound enabled Loco), Start/Stop/Speed and other digital commands are send thru the command controller via the tracks to the wheels and finally to the decoder. Which then the Loco decrypts and operates on board functions accordingly