Designing an Outside Broadcasting Vehicle - Report Example

MEDIA TECHNOLOGY The aim of the channel M project is to design a out broadcast vehicle consisting of a high definition television. The design outlinewould consist of the following. 1. The choice of vehicle parts and fittings: The truck can be designed around the Panasonic MX-70 8-input SDI production switcher because of its powerful features and small form factor.  It has a 8’x10’ control room, space is a primary consideration.  To accommodate monitoring all switcher inputs and on air elements Miranda Kaliedo Alto screen splitter feeding a Panasonic 50” Professional Series HD Plasma Display can be selected.  Because of limited production schedules and some very expedited editorial needs, the system design includes an Apple X-Serve Raid, disk array supplying real time SDI video in and out of the switcher.  At the front end of this Apple system, are three Final Cut Pro HD workstations for all the pre and post editorial, networked with Apple X-Serve and Xsan policing file management.  This SAN configuration allows all the workstations to share files in real-time and drive SDI video to the switcher live and back to the X-Serve Raid.  For b-rolls and live to tape two Panasonic AJ-SD93 DVCPRO 50 VTR’s are selected. In addition, the truck is outfitted with a Sony J30-SDI so Amp’d can roll-in betacam formats as well.  Because of the nature of the live events Amp’d shoots, a Doremi two-channel, SDI, MPEG 2, 4:2:2, 3-hour video server, was installed for instant playback and record with slow-mo.  The audio of for Amp’d #1 starts from the embedded SDI external source, de-embedded and then is routed throughout the truck in analog pairs.  A Mackie 1604-VLZ Pro, 16-channel analog mixer then handles the final mix.  The Genelec 8020a’s near field audio monitors handle program audio.  Because this truck is also equipped with a talent voiceover booth and often takes external camera feeds, a Clear-Com MS-232, 2-channel communications system is installed as a master user station with number of Clear-Com RM220 fixed user stations and Clear Com RS-602 belt pack stations. For live talent a Clear-Com AB-100 Announcer console is used with a Sennheiser HMD-25-1 Headset for IFB (Interrupt Feedback). The truck and chasis are designed by Renegade.  With a full motor home front configuration for support on location and plenty of power from its on-board 50 amp generator.1 2) Bock shemantics The video system consists of the following: • High Data Rate Digital ENG System • Single or Multiple Video/Audio • Optional DVB-ASI or SDI Inputs/Outputs • Video Encoding 4:2:2 and 4:2:0 • Video Low Delay Mode < 100 msec • Occupies < 12 MHz bandwidth at 2 GHz with • Occupies < 25 MHz bandwidth at 7 GHz with • ATSC VSB Modulation with Superior FEC • Robust Adaptive Equalization • Switchable Bandwidths 12, 17 and 25 MHz for Flexible Operation between 2, 7 and 13 GHz • Ideal for Multiple DMA Area Operation • Operates with any ENG Digital Radio • Small, Compact and Low Cost. Advantages of the VSB Modem: • High Data Rates over 12 MHz BW • Data Rates to 80 Mbps • Multiple Video Channels over a Single ENG Microwave Link • Ideal for Component HDTV • Low Cost and Small Size • Resilient to Multi-Path Block Diagram of the Three Video ENG System The audio system would consist of the following: As technologies continue to advance, audio is no exception. Surround sound, audio effects, descriptive video, and multiple languages or maybe combinations of these are required, thereby increasing the number audio channels. In the analogue days, each audio signal required a balanced pair of wires and an XLR connector.  This is no longer practical for multiple audio channels, and at least with AES/EBU digital audio, we can accommodate stereo on one coax cable. (Even in Europe, where engineers traditionally use balanced digital audio, most outside broadcast facilities are adopting coax cables for unbalanced AES audio). Surround sound comes in different flavors, the most popular being 5.1. This means Left, Center, Right, Left Back, Right Back and Low Frequency Effects (LFE) – 5 full bandwidth and 1 low frequency narrow bandwidth channel. Four AES channels can accommodate this requirement with some room to spare, but the resources quickly get used up if you also want special effects or multiple languages. To satisfy these additional needs, 8 channel audio embedders, de-embedders, frame synchronizers and other products, are readily available, potentially accommodating up to 16 mono audio channels. The use of Dolby 4:1compression technology greatly simplifies the transport of multiple audio channels from point to point across TV networks (Dolby E) and for transmission to the consumer (Dolby AC-3). Consequently there is sometimes a need for a truck to have the capability to decode Dolby-E or AC-3 from an incoming feed and to re-embed Dolby-E audio in the transmitted output. To satisfy these demands, Evertz has designed cards to convert embedded Dolby audio to discrete (and embedded) PCM AES and also to re-embed Dolby encoded audio for the trucks transmitted signals.    The TDM Switch core provides a 16,384 by 16,384 channel, non-blocking switch targeting telecommunications applications. Data is organized into 32 streams on the input and 32streams on the output. Each stream operates at 32.768Mb/s and uses a data format compatible with the ST-BUS protocol. Each stream transports 512 channels, with each channel supporting a bandwidth of 64Kb/s. Lower stream rates are possible for compatibility with other ST-BUS devices. Data passing through the switch has a latency of two frames. The timing of the output frames are locked to the input frame. FUNCTIONAL DESCRIPTION The switching function operates on individual channel timeslots, which are written to a data memory sequentially. A Connection Memory is configured to control the order in which the timeslots appear on the output of the Data Memory. The switch uses a Connection Memory to store the map between the input stream timeslots and the output stream timeslots. The Connection Memory is organized as a 16,384 x 14 bit array. The address format of a location in the Connection Memory represents a source stream and channel number, while the data value in that addressed location represents the destination stream and channel number. Broadcast switching is supported by mapping a single source channel onto multiple destination channels in the Connection Memory. This memory may be written to at any time to update the switch configuration of a give channel/stream without affecting the operation of other channels/streams. Data Memory :Data is written sequentially, with each read access controlled by the Connection Memory and Memory Interface: The channel mapping is written into the Connection Memory via the Memory Interface, which provides a simple synchronous interface. Signal Distribution Large trucks need large routers. They also need many distribution amplifiers. For greater space- and cost-efficiency using a combined down-converter and distribution amplifier (DA) is advisable. Alternatively, considering dual DAs in the OB truck also goes a long way. Fitting up to 32 HDTV DAs, each with 4 outputs, into a single 3RU frame (for 128 outputs total) is possible and very significant when you consider how many DAs you might need with a 256x 256 router. Time Code A time code generator has always been a standard piece of equipment in outside broadcast vehicles. Sometimes LTC is enough and a standard generator will suffice, but at other times there will be a need for Ancillary Time Code (ATC) and a new device will be needed. ATC is the HDTV equivalent of Vertical Interval Time Code (VITC) and there is a new generator available to address this need at the same time as burn the time code into the HDTV video, and also re4ad and generate Monitoring Will CRTs soon become a thing of the past? The ABC truck mentioned earlier used a flat panel LCD display for each source. These days there is a growing trend towards using multi-screen processors for a number of reasons. Clearly there is significant weight, space and power savings to be made by adopting multi-input display solutions over multiple CRTs. Major operational benefits may also be realized, because layouts and pictures sizes can be changed at the press of a button. Wiring is vastly simplified and the vehicle becomes far less cluttered because UMDs, tally lights, audio meters, up/down counters and even clocks can all be programmed into the same system. So are there any disadvantages?  Some will argue that they don’t want all their “ eggs in one basket” and fear that a monitoring failure will leave them blind. Cost also becomes a consideration compared with a traditional CRT wall. Regarding redundancy, early multi-screen display systems did indeed have single points of failure and most relied on a Windows® operating system. This is not longer the case, as the latest multi input display processors run their own real-time o/s, one not PCI based nor rely on hard-drives.  In addition, multi-image processor solutions offer several redundancy schemes – both via hardware and software to avoid catastrophic failures. The benefits of multi-image display monitoring can carry a higher initial cost.  However when comparing with conventional CRTs, it is important to take into consideration the hidden costs of conventional monitoring Fiber Optics Finally fiber optic cables are wonderful for OB vehicles. They take up a lot less space and they are much lighter to transport. Whether you want to carry HDTV, SDI, PAL, NTSC, audio, data, RS422, or whatever, there are fiber converters available for every type of signal.  Different signal types can also be multiplexed onto a multi-mode or single mode fiber. Evertz offers the world’s widest range of fiber modules, and having them fit into the same frame as the terminal gear offers a convenient solution that is flexible, expandable and upgradeable.  Fiber cards can also share the same SNMP monitoring system used by the other products and can save time and frustration when trying to locate a fault condition. 3) The costs involved are very effective and affordable. The whole set up is simple and involves meager complexity and can be assembled and dissembled very easily. Some key benefits can be added: •29MPG EPA Certification •Turbo Diesel Engine with 300K   Estimated lifespan •Onan Quiet Diesel Generators up to 12kw! •Dual HVAC Units (Up to 30,000BTU’s!) •Comfort for 4 operators •Maximum Rack-space Design •Extremely Lightweight Design Maximizes Grip capacity •Masts Up to 56 feet •SNG Antennas to 1.8 Meter. 4) Other suggestions could be regarding space. OB engineers are forever fighting with space and weight issues and HDTV equipment manufacturers have made some striking developments to address these needs. For example, conventional modular frames (or trays) typically have rack depths of over 400mm. Newer distribution frames like the highest-density modular 500FR (16 slots) from Evertz is only 260mm deep. This frame houses a whole range of distribution amplifiers and converters. Another way to save space is to design multi-purpose devices. OB vans will typically need two SPGs (Signal Pattern Generators) and a changeover, one or two master clocks and probably a time code generator and a means of synchronizing this with the SPG. The Evertz 5600MSC is device which generates conventional syncs, tri-level syncs for HDTV, SD and HD test signals, master clock time code and video time code all in one box. Bibliography: “Broadcast vehicle” Read More