This is Geoff's SMA37 DCC front end adapter: "Simple DCC Connections for Wide Decoder Adaptation."
It's a small, simple interface to convert DCC signals allowing a wide variety of Arduinos, PICS, Raspberry Pi’s or other processors, to utilize a native DCC signal straight from your layout bus. With this you can build DCC decoders with the likes of an Arduino Mega2650 which has 67 input/output pins available for decoder use, or try using a Teensy 4.0 with 600MHz clock speeds. A low-cost printed circuit board is offered, as well as a couple of interface tips for the modeler.
Details can be found at https://model-railroad-hobbyist.com/node/41187
We offer this as a panel of 12 circuits.