Abstract: A data transmission system includes probes connected between end user sites and a data switching network. Each probe is connected to the switching network via an access channel wherein transmission circuits establish paths between the sites through the access channel and switching network. The probes capture and retransmit data traveling between the sites over respective transmission circuits, and can thereby insert service level analysis (SLA) messages into the data traffic in order to actively communicate network performance information to other probes. For each transmission circuit, the probes periodically collect measurements related to one or more network performance metrics, including: round-trip delay (RTD), data delivery ratio (DDR) and network availability. During each SLA measurement cycle, a sequence of SLA messages is exchanged over each transmission circuit, which messages contain data used to determine RTD and DDR.

Abstract: An antenna enclosure comprising building elements and a support structure is disclosed. The enclosure is designed to be substantially transparent to electromagnetic waves and to have the appearance of the surrounding architecture or locale so that the antenna does not cause an obtrusive visual distraction.

Abstract: A data multiplexer system is comprised of a space division multiplexer having a plurality of space divided (SDM) input channels, each SDM channel adapted to carry a first number of time divided TDM channels at a first clock rate; at least one digital data source; apparatus for generating a second clock rate derived from the first clock rate, which is at the clock rate of the data source; apparatus for selecting data from the one source in synchronism with the second clock rate; and apparatus for applying the selected data to at least one of the SDM channels; whereby data from a digital data source having a clock rate either the same or different from the clock rate of a TDM channel may be applied to and be carried by any SDM channel.