data port characteristics

    the fcd-2 synchronous data channel supports user-selectable transmission rates, which are integer multiples of 64 kbps, up to a maximum of 1984 kbps. threetypes of data channel interfaces are available: v.35, x.21 or rs-530. in addition, v.36/rs-449/422 is supported by means of v.36/rs-449/422 adapter cables. the desired interface for synchronous data channel is selected by installing the appropriate types of user-replaceable data channel module.

    main link characteristics

    the fcd-2 main link meets the requirements of itu-t g.703, g.704 and g.732, and support 256n and 256s multiframes (2 or 16 frames per multiframe, respectively), in accordance with user's selection. fcd-2 also supports the crc-4 option specified in itu rec. g.704. crc-4 use is user-selectable.

    the main link has two line interfaces:

    1 120ω balanced line interface terminated in a d-type 15-pin female connector

    2 75ω unbalanced interface terminated in two bnc female coaxial connectors.

    line coding is hdb-3. the balanced interface transmit level is 3v, and the unbalanced interface transmit level is 2.37v. jitter performance complies with the requirements of itu rec. g.823. when the balanced interface is used, the maximum line attenuation, without ltu, is up to-10 db; when the integral ltu is used, the maximum line attenuation is up to-33 db, for a guaranteed range of upto 1.65 km (1 mile). this allows fcd-2 to operate as a short-range modem.

    timing

    multiple clock source selection provides maximum flexibility in connecting both the e1 and user interfaces.

    1 e1 main link timing can be locked to one of the following sources:

    (1)the recovered receive clock

    (2)internal oscillator.

    2 synchronous data channel timing. the fcd-2 data port has three timing modes:

    (1)dce-fcd-2 provides rx and tx clocks to user equipment connected to synchronous data channel.

    (2)dte1-fcd-2 provides rx clock to user equipment connected to synchronous data channel and receives the user tx clock.

    (3)dte2-fcd-2 receives both tx and rx clocks from the equipment connected to the synchronous data channel. in this clocking mode the e1 link rate can be locked to the clocks supplied from the user data channel interface.

    timeslot mapping

    two user-selectable methods can be used to perform the mapping of the synchronous channel data into the main link timeslots:

    1 bundling into consecutive timeslots

    2 placing in the user-defined timeslots.

    alarms

    fcd-2 stores alarms detected during its operation in a buffer that can hold up to 100 alarms. during regular operation, the front panel lcd display shows if there are any alarms in the alarm buffer, to notify the local operator that alarm conditions have been detected. the local operator can then review the contents of the alarm buffer on the front panel display, and can delete old alarms. in addition to the alarm buffer, the front-panel led indicators display in real time the e1 link status and user synchronous channel activity, and alert when test loops are present in the system.

    management

    setup, control and monitoring of status and diagnostic information can be activated from the front panel or via an ascii terminal connected to the supervisory port.

    1 front panel control. fcd-2 can be controlled by means of a simple menu, operated by push buttons located on the front panel. during setup, an lcd display guides the operator in the execution of the desired operations. the display provides information concerning the current system configuration and operating mode, and the available values of each programmable parameter. in case of operator errors, fcd-2 displays a message that explains the error and helps the operator take the correct action.

    2 ascii terminal control. fcd-2 can be controlled by means of an ascii terminal connected to it via rs-232 supervisory port. the ascii terminal management provides full control over fcd-2 operation, remote reading of alarm messages, and remote monitoring of fcd-2 operation from a standard ascii data terminal, using either point-to-point or polling communications. for polling purposes, each fcd-2 can be assigned an eight-bit address, for a maximum of 255 nodes (the zero address is reserved). optionally, fcd-2 can control a hayes compatible dial-up modem (operating in the auto-answer mode) to provide call-in capabilities.

    call-in function. a remote operator located at a central site can perform all the functions available from a supervision terminal directly connected to fcd-2. optional password protection is also available.

    diagnostics

    the fcd-2 diagnostic capabilities include local and remote loopbacks at various points, as well as built-in bert for rapid identification of faults. maintenance is further enhanced by advanced self-test capabilities, which provides circuit-level diagnostics data.

    performance statistics

    fcd-2 supports three types of performance statistics:

    1 e1 bipolar violations (bpv)

    2 crc-4 errors

    3 out-of-service (oos) events.