Abstract: A cell grant mechanism is presented which allows a central device to control the transmission of cells from one or more remote devices connected to the central device over a physical medium. Grants are issued from a grant table in the central device to allow remote devices to transmit cells to the central device. The spacing of the grants are optimized to minimize cell delay variation. When there are unused cell opportunities, central device can issue grants to devices to utilize the unused cell opportunities on an available bit rate basis.

Abstract: In an Asynchronous Transfer Mode (ATM) communications network which operates over a shared media a method of addressing and access control between a central transceiver and multiple transceivers in a residence is required. A device identifier is placed in the in the Generic Flow Control (GFC) field of the ATM cells to indicate that cells are designated for a particular transceiver or transceivers in the residence. In the reverse direction, transceivers in the residence use the GFC field to indicate that they are attempting to sign onto the network. The GFC bits are returned to zero prior to passing the ATM cells to the ATM processing layer.

Abstract: Digital data is transported bidirectionally between a broadband network unit and devices. The data is transmitted in a series of frame intervals that include request slots and cell slots for transmission of ATM data. The request slots may be used by a device to request one or more cell slots. The broadband network unit determines which requests to grant. If the request is granted, the device may use the cell slot to transmit ATM data. In addition, the request slot can accommodate Time Division Multiplex data such as digital telephony.

Abstract: An optical spectrum analyzer is provided with a user selectable sensitivity. Required operating parameters are set in response to user selection of sensitivity to permit measurement of an input light beam at the selected sensitivity. Setting the required parameters includes setting a required gain of a video channel to permit measurement of a specified maximum light signal and to provide the selected sensitivity, setting a required video bandwidth of the video channel to provide the selected sensitivity at the required gain of the video channel and setting a sweep rate to provide the selected sensitivity at the required video bandwidth. When the normal bandwidth of the video channel is not adequate to provide the selected sensitivity, the electrical signal is passed through a digital filter having a filter coefficient set to provide the required video bandwidth. A peak detector is incorporated in the video channel to accurately measure signal amplitudes in a fast scanning condition.