Abstract: The cellular telephone interface system has the capability to automatically choose between AMPS and CDMA cellular transmission protocols for data transmissions. The cellular telephone interface system includes a PC-modem card, such as a PCMCIA card, for interconnecting the cellular telephone to a data source, such as a laptop computer, portable facsimile machine, or the like. The cellular telephone is capable of transmission in accordance with either AMPS or CDMA transmission protocols. For AMPS, the PC-modem card converts data signals received from the data source into PCM signals for forwarding to the cellular telephone. The cellular telephone converts the PCM signals into AMPS formatted signals for transmission to a local cellular base station. For CDMA transmission, the PC-modem card converts the data signals received from the data source into RS-232E signals for transmission to the cellular telephone.

Abstract: A compliant chamber is formed in a fluid line which connects a fluid supply to a fluid receiver. The compliant chamber is alternately in fluid communication with the upstream and downstream segments of the fluid line. When the chamber communicates with the upstream segment it receives and stores fluid at the head pressure. When the segment communicates with the downstream segment, a pressure equalization pulse occurs. A pressure sensor in the downstream segment measures the pressure equalization pulse which is proportional to the head pressure. Processing the equalization pulse with the downstream fluid system resistance, the compliance of the compliant chamber and the equilibrium pressure results in a determination of the head pressure. Comparing the head pressure to thresholds permits determination of an occlusion or empty fluid supply. Where a peristaltic pump is used, the chamber is formed between the end fingers of the pump.