The abbreviation ADT stands for "Acoustic Drum Trigger". This already reveals what this device is supposed to do: Converting any kind of signal such as drum mike, line signal or ordinary trigger pulses into clean midi signals without cross talk. The ADT is one of the last products having been available at the beginning of the nineties wearing the (new) Simmons logo but the backside of the chassis carries the company name "Soundunit Ltd. Hitchin, Herts, England". Also the chassis' design has nothing to do with Dave Simmons' black boxes.
In the light of 1992 the ADT was equipped with pretty advanced features such as the so called "learn" function (building velocity curves out of external reference signals instead of preselectable curves), signal compression/expansion to avoid crosstalk, 2 line 32 character backside lighted matrix display, trigger in/through per channel, memory for 50 patches, foil buttons, Midi in/out/through, no on/off switch (buh!). Cool device but -as we all know- not the saviour of Simmons products