Km/h - defined speed control as alternative to today's
usual method of percent scale graduation.
To interpret DCC speed steps (128 in modern systems
and decoders) as absolute speed in km/h or mph - actually an obvious
idea and yet, was only recently taken up in public discussions. The
proper setting of the already present CV #5 (top speed) does not bring
the desired results. ZIMO puts this idea now into practice with three
steps:
- A new CV as conversion factor, which takes
into account the scale (HO, O, 1 etc.) and length of the calibration
track (see below); to be entered with the help of a simple formula.
-During a calibration procedure, the loco is
driven at a given speed for a predetermined distance (e.g. 15 feet).
Passing the start and end of the line is recorded by activating a
function (semi-automatic procedure) or a decoder input (Reed switch or
similar for fully automated procedure).
- This kind of control is not just for a visually
pleasing drivability, which is the main task of today's load regulation
or back-EMF, but rather to hold a desired speed exactly, in km/h
or the distance to reach a full stop. This new demand is reached by
continually calculating the already driven distance and applying the necessary
changes. The required data (EMF values, taken up to 200 times per
second) and the processing power is available in all current ZIMO loco
decoders.
- Using km/h or mph for controlling loco speed adds a
number of other operational advantages; from the strict observance of
speed limits to the precise calculation of arrival times at the next
station. Consist operations should also profit from such precise speed
control - although field tests have yet to be performed to confirm
this.
The mph speed control is also related to the
announced "distance controlled stopping" but is not yet
included in this version.