Emergency Operations Center: CATV Headend
Nov 17, 2010 10:30 AM, By Cynthia Wisehart
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For incoming signals, survivability design dicated multiple antennas in parallel paths for broadcast and satellite sources with impedence-matched utility gain active multicouplers and stacked distribution methodology. Photo by Ron Baker
“We started with discussions with the three stakeholders—the Emergency Management Department, the Los Angeles Police Department’s Real Time Analysis and Critical Response Division, and the Los Angeles Fire Department—and gained a rich understanding of their unique cultures and how the three departments operated and communicated internally, and with one another,” says Spectrum principal John Bilar.
Originally Bilar envisioned a single high-definition, hybrid analog/digital CATV system throughout the EOC facility. “However, it became clear that we needed a hybrid design with shared, yet independent news and information CATV distribution for three distinct and separate departments.”
The requirements included: Internal distribution of broadcast TV channels, multiple HD satellite news channels, selected local cable TV channels, and AM and FM radio sources; the ability for departments to personalize their individual CATV distribution with several channels of specific internal content and an internal scheduling channel; the capacity to generate high-definition department broadcast channels of a digital image source (selected via touchpanel), such as incident and resource status, EOC PC-based management applications, hazmat and fire area maps, Web media, and camera image sources from helicopters, vehicles, ATSAC, LARCOPS, city facility closed-circuit systems, and other classified imaging systems. In addition, each department needed to selectively share digital images/sources with other departments, with the ability to grant or revoke access on a per-source/per-destination basis, from their control panels. To accomplish this, Spectrum used an approach developed from one of its many Department of Defense design-build projects. From a touchscreen, users can select from a large number of classified high-resolution computer sources, set up a bank of preview displays, and then grant permission to a group or groups in various venues to view that specific array of sources. The user can also revoke the array of images previously sent to a specific destination on a case-by-case basis.
The users did not want set-top boxes, and adding viewer positions needed to be at minimal cost and effort. This was accomplished by modulating all sources into the single shared baseline CATV distribution system. The system uses a secondary headend in each of the equipment rooms to provide department security and a location for department-specific local inserts to be incorporated into their CATV system. “The city project administrators were expecting a satellite HD set-top box at each viewing position at an estimated recurring facility cost of several thousand dollars each month. We negotiated directly with the satellite network, and by properly identifying the six key modulated system requirement conditions, we were able to reduce the recurring facility cost to less than $120 per month.”
Here’s a source breakdown:
- 10 satellite. HD-component analog receiver outputs to AJA HD-SDI converters to Adtec digital encoders to deliver the ASI stream, and then to Blonder Tongue QAM modulators to insert the signals onto the EOC’s QAM CATV System. Bilar says that for future systems, he would test and evaluate the Contemporary Research QMOD-SDI to replace his $25,000-per-HD-channel chain with one box at $3,000 a channel.
- 15 Blonder Tongue ATSC-to-QAM transcoders
- 10 cable TV. The cable provider’s set-top box provided an NTSC signal that was modulated onto the EOC’s CATV system.
- 45 fiber feeds. Five venues within the three departments each provide nine digital fiber feeds to the CATV master headend. From here, eight of the fiber feeds can be distributed among the various departments. The ninth digital fiber feed from each of the facilities allows each department to selectively QAM-modulate any of their local high-definition digital video sources onto the EOC’s shared CATV system for the department broadcast channel. Nearly any PC, DVD player, camera, etc., can be routed to the CATV system for QAM-modulation and distribution throughout the entire EOC.
