Up, Down and Cross Conversion
Early generation up-converters were typically 2RU. It became evident, when one of the first mobile operators specified a need for 22 up-converters, that a much smaller package was needed. Today, six or seven up-converters can be accommodated in a 3RU tray.  Why so many up-converters?  Since many sources are still in standard definition format, generating an HD format in an HD truck is a must. For example most companies already have many inexpensive standard definition cameras, which they would like to keep using for shots inside goalmouths, on helmets of racecar drivers, and other vulnerable places. The BBC even installs TV cameras in cricket stumps! Using upconverters, SDI logos, keys and fills can also be translated into the HD format. Up-converters like many other products also need to be capable of addressing different HDTV standards.
Along with up-converters, there is a need for a large number of down-converters. Since the majority are required to supply feeds to inexpensive monitors it is common to see combined down-converter/distributions amplifiers (commonly referred to as DCDAs). These devices typically have 4 or more HD and 4 or more SD outputs, which may also be either SDI or composite video capable. A typical large truck might use between 50 and 100 of these, depending on the number of display monitors.  As well, the other type of down converter is the “broadcast quality” down converter, which may be used for simultaneous broadcasting or recording in both HD and SD standards.
Which HDTV standard to adopt is a commonly pondered question, and most resolve to selecting at least two.  1080i lines provide the best resolution commercially available today, but 720p has some compelling advantages for sports because of its higher frame rate and lack of interlace artifacts. Truck operators have a desire to own vehicles, which can handle all standards, so there is a definite need for cross-converters. A Cross-Converter can accept either input standard and convert it to the other. At the same time many cross-converters should also handle up and down conversion, as well as correct aspect ratio conversion and transfer embedded audio to the new standards. (The Evertz 7710XUC-AES4-HD can perform all of these tasks and you can get seven of them in a 3RU frame.)

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! But, what about reducing the router size itself? Stay tuned for more!

Further Space Savings
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. Two of these and a changeover is all you need.

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 conventional LTC.

Common Control
Each outside broadcast venue is quite different and many hours are spent at each gig adjusting levels, video phases and other parameters.  Major advances have been made in recent years in computer networks and now these benefits are creeping into the OB truck business. It is now quite easy to connect all video and audio devices onto the same network so that all products can be controlled from one or more locations using computers or computer literate control panels. All that is required is an IP address for each device and Ethernet cabling to connect the various computers, panels and Ethernet routers.  Now you can control any product from any place but even more important, you can save and recall multiple configurations for each product or groups of products (commonly referred to as a service). This is extremely powerful. It means that after spending a few hours tailoring your truck to a venue, you can simply save the configuration as, for example athens.cfg and next time your truck returns to that location in Athens, the same configuration settings are automatically recalled – a fantastic time saver. 
Alarms are also possible. In a live OB coverage where operators must be alert at all times, the advantages of this might not seem as important as let’s say in a playout center, but on the other hand, the ability to immediately see where an error has originated, can significantly reduce down time. It is also desirable to log all errors to improve future performance.  Network management systems running SNMP (Simple Network Management Protocol) such as Evertz’s VistaLINK® can provide both monitoring and configuration control, and unite hardware to a single networking platform.

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.  You will have to add up the cost of the UMD and tally devices, additional clocks and timers, any audio meters needed and the wiring for these items. You will also need to offset the cost savings in routers because a router crosspoint I/Os, commonly allocated to drive any input to any output display, an now be handled by the multi-image display processor itself.  Further, the savings in power and air conditioning must also be considered.

Audio
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. 

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.

Conclusion
With over thirty OB trucks successfully using Evertz HDTV, fiber and multi-input display gear, we are proud of our technology and service experiences. If working on OB projects, contact Evertz today for more information on how Evertz can future-proof your needs.