An apparatus for depositing film stacks in-situ are described. The method and the apparatus determines whether to adjust the PCS threshold to use a shared channel for transmitting data in a wireless network based on a congestion status of the shared channel, and adjusts the PCS threshold based on a packet loss measured for a predetermined period of time. In another embodiment, the flow path volume in the forward direction can be greater than the flow path volume in the rearward direction in order to provide a greater flow volume in the forward direction. Embodiments of short length create an inexpensive spring having a generally rectangular platform; longer embodiments create an inexpensive spring in the general shape of a box beam. The results of the multi-level classification system are applied in real-time to provide feedback to the user via an audio or visual alarm, or are recorded for subsequent off-line analysis. The master sends the command to the slave in response to the acknowledgement signal sent by the slave.