Digitrax decoders with numbers ending in "3" have SuperSonic™. Decoders control the locomotive's speed through Pulse Width Modulation. When these pulses are within the human hearing range, it can cause some buzzing in some locomotives.CV09: SuperSonic™ The SuperSonicTM feature allows you to adjust the PWM (pulse width modulation) frequency of your decoder to reduce the humming noise that is characteristic of the DCC signal. Digitrax decoders that have this feature are shipped with the value set at 000/x00 or maximum PWM. To change this value, you can set any value from 000/x00 (max) to 255/xFF (min). Use of this feature ...
Your locomotives look like the real thing, Digitrax LocoMotion™ System makes them run like the real thing, too! 128 speed step control. Smooth deceleration to stop before changing direction when locomotive is reversed. No sudden, non-prototypical stops! Torque compensation for the smoothest operation ever. Momentum with acceleration and deceleration settings. Set normal direction of travel for your loco. Switching speed feature for quick access to slower switching speeds. Simple 3 step speed tables are easy to set up. Advanced 28 step speed tables with 256 level resolution. Scaleable speed stabilization feature. ...
You can simply add a TL1 or TF4 to locos with decoders made by other DCC manufacturers. In the case of some supersonic decoders made by other DCC companies that are not transponding compatible, you will need to turn off the supersonic feature when you want to use transponding. Digitrax supersonic decoders are compatible with transponding and can be used in supersonic mode while transponding.