Not sure if I can say this properly so here goes nothing.
Think for a bit that all communications to and from a model train was done with magic, light, radio, sound, what ever , What does that model train still need and what can the other ways of communications not easily provide?
1. POWER: With dirty track, track switches, ____ there is even a need for short term power storage.
2. Position: Older systems did block detection. DCC makes this harder but not imposable. But what if you wanted more? What if the currently addressed train created a large current change, A current pulse in one or both directions. Block detection of this current pulse would allow knowing what block the addressed train is in. But could you not do more with the pulse with some timing like a TDR to determine where in the block the train is? While on position, how hard would it be for the controller added to a train to detect the rotation of the train's motor? Good detection of the motor rotation could give a mouse like reading. Just one pulse per rotation with the gear reduction would give good readings. Just one cheap optical sensor, a led, a black mark and a way to talk back and you could have mouse like counter telling you how far the train engine moved.
Back to main thought.
Previous systems to DCC had problems with signal strength. Some had EMI problems. Some had DC balance problems. If you think about it, what DCC did was make the communications to the train HUGE. So huge that the dc power could no longer exist, but done in a way that the signal it's self could be used for the train;s power source.
Now I can understand in the limited space of a small train engine not having great filters to remove in train power supply noise. I can understand the communication signal getting a little distorted do to the small amount of space in an engine.
But what is the excuse for things that do not have these tight space problems? If you look on the net, how many projects forget that what is on the track is first a communication signal and second a more expensive to create DC power source? What is the excuse for something not in a small space like a train engine pumping a lot of power supply noise back into the track signal. All that noise and distortion keeps adding making it harder for any talk back from the train system to function. It gets large enough that things with out talk back start messing up even with the huge signal DCC starts with on the track. Look at the strong suggestions made to use a separate DCC booster to power things Yes I know you can get away with a lot, but would it not be a good idea if a circuit that was using the track signal to power the circuit to have a proper filter between the power section and the signal input to remove the noise generated from the power section?
Is it really that hard to keep a DC input from messing with signals which are above 3 kHz that are also connected in front of the DC input?
C
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