A system for background image subtraction includes a computing device coupled with a 3D video camera, a processor of the device programmed to receive a video feed from the camera containing images of one or more subject that include depth information. The sub-passage defines an open upstream end and an open downstream end to direct a portion of the bypass air flow to pass therethrough. The data to be considered is established by timing offsets dependant upon packet header lengths, and a function to be performed on the data is controlled by individual control units based upon template information individual to each control element. The receiver determines whether all parts of a packet are received before expiration of the time interval, wherein the received packet is valid if all parts are received before the expiration of the time interval. As a result, there is no possibility of ejection at the nozzle tip onto a substrate simultaneously with ejection of photoresist.