This disclosure describes a chopper mixer telemetry circuit for use in a wireless receiver. The received corneal endothelium image data is analyzed and the analysis result is transmitted to the client terminal. A first controller monitors the second sensor, and a second controller monitors the first sensor. The base station also transmits to the first subscriber station using a cyclic delay diversity scheme having either zero delay or non-zero delay according to the amount of antennachannel correlation observed at the first subscriber station. Other embodiments and features are also disclosed. The hoses unravel from their reels and are propelled up the tracks by rotating rollers.