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AT&T Broadband Restoration

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  • OZOB99
    A brief recollection of analog broadband restoration methods & procedures in Long Lines facility offices from the 1950 s through the 1980 s: As L carrier &
    Message 1 of 2 , Aug 1, 2010
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      A brief recollection of analog broadband restoration methods & procedures in Long Lines facility offices from the 1950's through the 1980's:

      As L carrier & radio routes started their rapid growth in the early 1950's it was apparent that organized coordinated plans & dedicated equipment would be needed for timely restoration of failed/damaged broadband carrier facilities.

      Protection channels automatically cared for the occasional failures, but in the early years an additional failure on that route(or total route failure) had to be restored manually(and improvisationally) via patching/trunking on whatever spare slots and/or other protection channels could be found to the distant terminal.

      This quickly led to developement & implementation of preplans,restoration patch bays,dedicated WLEL(wire line entrance links;between radio and LMX equipment),intra-office patch trunks,special order wires, centralized control/coordination(regional facilty control offices,e.g. Monrovia,Rockdale,et al). This process was accelerated in key locations by the growth of priority gov't circuits during the Cold War, & even more so after the UT/NV bombings in 1961 and the Cuban Missle Crisis. The offices with master groups carrying high priority gov't circuits had expedited installation of restoration equipment and subsequent upgrades.As a result of this expedited restoration capabilities for gov't services, all AT&T customers benefited from shorter outage time on facility failures.

      An early use of broadband restoration was patching failed K CXR groups on spare L or R LMX group slots(via patch trunks); usually to the end office having the same K and L or R route, but if no spare slots it could be patched through 2 or more intermediate offices to back haul if needed.

      Initially a failed mastergroup unable to be restored on it's own protection channel was patched to another route's protection channel, often involving other routes/cities in tandem; multiple MG failures were patched on other available protection channels,often involving several offices.Besides manual patches, coax switches were operated at the terminal and remotely at aux stations.

      With higher capacity facilities like L4,L5,TH several mastergroups from total route failures could be stacked via MMX(mastergroup multiplex) on those protection channels, becoming quite complex and coordination intensive.

      Every possible failure was covered by a numbered preplan,updated often due to growth,in a plan book at the restoration patch bay; with step by step illustrated instructions that even the supervisor could do with practice:) Each plan was called up periodically for "dry runs"and had a time goal ranging from 10 min to about 40 for the more complex;the facility control office recorded the entire event on the order wire/phone line and critiqued in depth with the office mgr(more than one screw up could have a negative impact on the supervisors salary next year).

      The restoration was initiated by the order wire(FP100-xxx) or a non-pub phone, with an extremely loud buzzer/bell, and every office was conferenced with loudspeaker on.



      After all patches/switches were completed a terminal office put a continuity pilot(560 KH I believe) on for verification at the receive end, the "bumped" to verify again; later a working mastergroup was double fed and the receiving office verified with a spectrum analizer, with the "bump".All MG's could be double fed transmitting via a hybrid out jack or switch.

      One of the hazards during a "wet run" restoration was "wrong message", double feeding the wrong MG & thus killing another 600 channels.


      Single circuit restoration/priority procedures can be found on post #9243.
    • charlie Fargis
      To avoid wrong message, part of the Restoration plan was to identify an idle circuit in the facility such as an idle message trunk or spare channel, send 1004
      Message 2 of 2 , Aug 2, 2010
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        To avoid wrong message, part of the Restoration plan was to identify an idle circuit in the facility such as an idle message trunk or spare channel, send 1004 Hz tone to the far end, and interrupt that to verify correct patching and switching.
        I remember those 560 khz meters. We typically used the WG set to be sure.

        And I will never forget when the Pottstown Monrovia L5 went down in Agnes.
        Our RPD was an unbelievable spaghetti bowl of coax patch cords.
        The HF folks even used a VF pad box for an improvised LL connector.

        That horn went off every afternoon in Philly for TV work. EA8503 was the plan from Garden City to New York 4
        for the evening news feed.

        R101 GCY-Randallstown to R101Randallstown to Philly to R 101 Philly to New York 4.
        We had a switch in the RPB to lock out the channel from Randallstown and switch the 70 MHZ IF to NY.

        Restorations were qualified as dry or wet. Dry was a drill, and wet was get it up because something is broke.

        To: coldwarcomms@yahoogroups.com
        From: ozob99@...
        Date: Sun, 1 Aug 2010 19:52:41 +0000
        Subject: [coldwarcomms] AT&T Broadband Restoration




























        A brief recollection of analog broadband restoration methods & procedures in Long Lines facility offices from the 1950's through the 1980's:



        As L carrier & radio routes started their rapid growth in the early 1950's it was apparent that organized coordinated plans & dedicated equipment would be needed for timely restoration of failed/damaged broadband carrier facilities.



        Protection channels automatically cared for the occasional failures, but in the early years an additional failure on that route(or total route failure) had to be restored manually(and improvisationally) via patching/trunking on whatever spare slots and/or other protection channels could be found to the distant terminal.



        This quickly led to developement & implementation of preplans,restoration patch bays,dedicated WLEL(wire line entrance links;between radio and LMX equipment),intra-office patch trunks,special order wires, centralized control/coordination(regional facilty control offices,e.g. Monrovia,Rockdale,et al). This process was accelerated in key locations by the growth of priority gov't circuits during the Cold War, & even more so after the UT/NV bombings in 1961 and the Cuban Missle Crisis. The offices with master groups carrying high priority gov't circuits had expedited installation of restoration equipment and subsequent upgrades.As a result of this expedited restoration capabilities for gov't services, all AT&T customers benefited from shorter outage time on facility failures.



        An early use of broadband restoration was patching failed K CXR groups on spare L or R LMX group slots(via patch trunks); usually to the end office having the same K and L or R route, but if no spare slots it could be patched through 2 or more intermediate offices to back haul if needed.



        Initially a failed mastergroup unable to be restored on it's own protection channel was patched to another route's protection channel, often involving other routes/cities in tandem; multiple MG failures were patched on other available protection channels,often involving several offices.Besides manual patches, coax switches were operated at the terminal and remotely at aux stations.



        With higher capacity facilities like L4,L5,TH several mastergroups from total route failures could be stacked via MMX(mastergroup multiplex) on those protection channels, becoming quite complex and coordination intensive.



        Every possible failure was covered by a numbered preplan,updated often due to growth,in a plan book at the restoration patch bay; with step by step illustrated instructions that even the supervisor could do with practice:) Each plan was called up periodically for "dry runs"and had a time goal ranging from 10 min to about 40 for the more complex;the facility control office recorded the entire event on the order wire/phone line and critiqued in depth with the office mgr(more than one screw up could have a negative impact on the supervisors salary next year).



        The restoration was initiated by the order wire(FP100-xxx) or a non-pub phone, with an extremely loud buzzer/bell, and every office was conferenced with loudspeaker on.



        After all patches/switches were completed a terminal office put a continuity pilot(560 KH I believe) on for verification at the receive end, the "bumped" to verify again; later a working mastergroup was double fed and the receiving office verified with a spectrum analizer, with the "bump".All MG's could be double fed transmitting via a hybrid out jack or switch.



        One of the hazards during a "wet run" restoration was "wrong message", double feeding the wrong MG & thus killing another 600 channels.



        Single circuit restoration/priority procedures can be found on post #9243.


















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