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05. Outside Broadcasting and Links

5.1 Remote Broadcasting
Remote broadcasting covers production in, or acquisition of program material from locations away from the studio center. News is an important part of radio and television broadcasting, and television, in particular, relies greatly on production that takes place outside the studio, for sports, music events, and drama production. Bringing outdoor events into the living room of the viewer is becoming more and more common. In order to record these events, the outside broadcast or OB vehicle with communication link is used.

Remote broadcasting can be categorized, normally, in two ways:
1. Remote News Gathering and 2. Remote Program Production
Remote news gathering is applicable in both the Radio and Television field. Electronic News Gathering (ENG) is the gathering or collection of news stories intended for broadcast during different radio or television newscasts. The technique is based on the use of portable unit such as portable microphones, camcorders, which combine electronic colour cameras and recorders in one single unit, portable mixer or laptop as editing unit. Preparing and transmitting news reports is certainly one of the most challenging task of broadcast organizations. For radio news the voice of the reporter is sufficient, but certainly not in the case of television. The mandatory requirement for any television newscast is the picture of the event, or at least of the location where it happened and the visual presence of the reporter on that spot.

Radio news gathering includes reporting from the field, recording interviews, press conferences, and so on, and transporting them back to studio centers for incorporating into news programs. Most equipment for radio news acquisition uses the same principles as fixed radio studio equipment. However, the emphasis is on portability, ruggedness, and ease of use in difficult conditions. Microphones are normally highly directional and may have windshields to reduce the effect of wind noise on the microphone diaphragm. Recorders are often small enough to be held in the hand and may use tape cassette, MiniDisc, or increasingly, solid-state flash memory, with both microphone and line-level inputs. Recorded media may be transported back to the studio for editing, or live contributions may be sent over contribution links of various types, it is also possible to transfer audio files from a digital recorder to a laptop computer and edit the material there.

The simplest live arrangement is the reporter speaking over a regular telephone line or cell phone. Wherever possible, the audio sent to a remote contribution site for cue purpose is a mix-minus feed from the audio mixer. This helps avoid problems with audio feedback and makes two-way communication with presenters and talent possible. The reporter may also have a portable receiver for listening to the station output off-air. ENG news team and their equipment may be transported in a small truck or wagon or may work with a larger truck that includes a microwave link or a satellite uplink for live communications with the studio. A portable camera can be used with a recorder.

The two most objectionable factors of early magnetic tape recorders were the limited signal quality and the separate camera-recorder configuration. It led to with the advent of the half-inch analogue component recording principle offering a clearly superior recording quality. The use of such smaller tapes enabled the construction of viable and portable camcorders. Although the analogue component recording format is still the most widely used one in ENG operations, digital recording is quickly taking over the area of ENG. Since the advent  of digital recording, manufacturers have developed a number of different formats. The first series of recording formats handled uncompressed digital component and composite video signals. But these formats were too expensive for ENG. Later, 1/4-inch tapes and different comparison schemes are used resulting in different video bit rates. These formats can be classified roughly into four categories:

  • Format using a proprietary low compression scheme (about 2.5:1);
  • DV-and MPEG-2 based formats, offering a video bit rate of 50 Mbit/s;
  • DV-based formats with a video bit rate of 25 Mbit/s;
  • Format using a proprietary high compression scheme (10:1). The selection of the most appropriate compression scheme for a given application should be based on the assessment of the following key parameters:
    • Overall picture and sound quality;
    • necessary multi-generation capacity; and 
    • required post-production margin.
In the domain of digital ENG acquisition, it is possible to distinguish three main types of camcorders. The first one uses magnetic tapes. The second category is represented by camcorders which are based on other recording media, while the third group includes camcorders that record simultaneously on a CD, video cassette and on a retractable hard drive. The DV-based camcorders which use magnetic tapes s the recording medium offer a very good price/quality trade-off. There is a wide selection of different DV-based camcorders on the market produced by several manufacturers. It therefore can be expected that in the future non-tape-based recording media could take centre stage in the ENG acquisition domain.

Finally, a combination of tape and hard drive recording is also available on the market. Such a camcorder has a dockable hard disks, solid state memories or DVD/CDs. In a television centre post-production is performed either on conventional linear editing systems or on non-linear editing unis (NLE). These non-linear editing units are either products specially developed for news making operations, or scaled-down versions of standard television production ones. In addition, NLE units can handle more than one compression format and deliver the finished item in any required form as well as encode the signal in MPEG-2 format for direct digital play out. ENG field operations require lightweight portable editing units. Digital or server-based newsroom systems are integrated to bring to news operations all the advantages of the merging of information and video/audio technologies. The aim of that integration is to create a unified user friendly system amongst different devices and subsystems.

Radio remote productions include live or recorded programming such as sporting events, concerts, promotional events at country fairs and other shows from outside the studio. Facilities required may range from simple to complex. Equipment is usually transported in carrying cases in a small truck and may include portable or smaller versions of equipment used in the studio of the following types:
Microphones, headphones, headsets (combined mic and headphone)
  • Audio Mixer
  • CD Players
  • DAT, MiniDisc, and Compact Flash Recorders
  • Monitor Loudspeakers

Other equipment that may be needed for some types of remote events includes the wireless microphone and public address amplifier and speakers. For live broadcasts, some of the same equipment as listed for news reporting may be used for communicating with the studio, and they are Remote Pickup (RPU) radio link system and portable antenna system for RPU.

Remote field production falls into two main categories: (1) electronic field production (EFP) with portable equipment and (2) mobile production relying on equipment installed in mobile vehicles. Electronic Field Production (EFP) normally uses portable self-contained equipment that can be transported in rugged shipping cases. Sometimes, however, EFP equipment may be installed in a small truck or van. EFP recording tends to be done with higher-quality tape formats such as digital Betacam or HDCAM.

Mobile Production trucks or outside broadcast (OB) vehicles have been used  for Radio and television broadcasting for decades. A vehicles serves as a mobile office/studio, the place where the audio person writes, records, mixes, and transmits. They provide most of the facilities of a fixed production studio, but in a mobile environment. The unit is divided into air-conditioned areas for production control, audio control, vision control, recording, and other equipment. Trucks may be powered from a main power supply at the remote site. For backup, a trailer-mounted and soundproofed electrical generator may be used. Some trucks have their own built-in generator. In developed countries broadcasters may even use helicopters for live news contribution, often during disaster period. Usually one person flies the helicopter and also may report the traffic or news.

In order to record these events (e.g. sport, a concert or an important national event or ceremony), there is increasing trend of using outside broadcast or OB vehicle. The design and construction of these vehicles requires a concentration of effort considering the complexity of applications. In the last decade digital technology has significantly had an impact on vehicle design, features and facilities. Apart from the high picture quality, the reduction in size of systems, synergized with lower power demands and less heat, have made the OB vehicle design become more relaxed in terms of weight and power consumption. Designing an OB vehicle is dependent on four different factors. These are vehicle purpose, choice of chassis and overall dimensions, country territory, extent of facilities.

Air-conditioning requirements within the vehicle will be wholly determined by the climate in which it is to be operated. A hotter climate means that more on-board air-conditioning equipment will be necessary for a given number of operators and for technical heat dissipation as well as any heat gains. Physical construction of the vehicle will affect the heat retention or loss. The provision of the technical facilities placed on board the vehicle will dictate the overall size of that vehicle. Large deployment of cameras and VTRs, a larger sound desk, more operators and engineering staff in turn increase the demands for a greater air-conditioning capacity.

5.2 Program Links
In Radio or Television broadcasting, links are required for receiving or distributing the raw or packaged program and news material. Program links fall into three main categories:

  • Contribution links for sending news contributions and other remote production material to a network or studio center.
  • Network distribution links for distributing network program feeds to multiple locations around the country.
  • Studio-transmitter links (STLs) for connecting a station studio center to its transmitter site.

Several types of links are used for each category for radio and television, based on different technologies. Contribution links are used to convey programme material from remote studios or ENG or OB Van to a production centre. In many instances these links will follow the same route as distribution links but in the reverse direction. For radio the links used can be telephone line, ISDN line, remote pickup units (RPUs) in the HF, VHF, and UHF bands, T1/E1 Line, or LAN/WAN links. Likewise, microwave, satellite and broadband T1/E1 lines are used as contribution links for television.

Audio facilities use various methods to transmit a signal from a location to the station and from there to the station transmitter. One of the oldest methods is a plain old telephone line. A microphone or a recorder is attached to a phone jack and the sound is sent through the phone switching system. These are phone systems such as ISDN and ATM that yield higher sound quality than PSTN phone. Another system called a remote pickup unit (RPU) uses a pre-allocated band of frequencies for electronic news gathering and other remote broadcasting. For this method, a small transmitter at the field location must line up with an antenna that a station has placed somewhere in the local vicinity, usually on a high hill. In order for the transmission to work it must be in line o sight. When sound needs to be sent longer distances, satellites are brought into play. There are two types of satellites, geosynchronous and low-earth orbit. Portable VSAT Terminals, linked to GSO satellites, are fixed on the OB vehicles top and used for transporting field news, events or programs into the main studio. Satellite phones that deliver audio from remote location use these LEO satellites. Wireless broadband is another way that audio facilities receive information from the field.

Distribution links are used to transmit video and audio signals from a studio to a broadcast transmitter or between broadcast transmitters. The programme distribution to some broadcast transmitters in a network will be carried out using either Public Telecommunication Operators (PTOs) provided permanent circuits, which are likely to be predominately Fibre Optic, or by satellite.

Until around 1980 all radio links employed analogue techniques and now almost all equipment used for telephony has been replaced by digital links carrying data and voice traffic. A system typically comprises the following items:

  • transmitters and receivers;
  • filters and circulations to multiplex transmitters and receivers to a common antenna;
  • waveguide or coaxial feeder and accessories between radio equipment and the antenna;
  • parabolic antennas with diameters ranging from 0.3 to 3.7m;
  • interface steelwork between antenna and tower or building;
  • service and/or auxiliary channels;
  • supervisory equipment;
  • power equipment
  • antenna support structure;
  • radio equipment room or cabin;
  • air-conditioning

Categorically, the technologies and links used on STL platform for Radio and TV are leased telephone lines, ISDN Line, T1 Line, microwave links, fiber-optic links and satellites. These links are used as depending on the broadcaster's requirements such as operation cost, availability of technology in the area, quality of signal required, and affordability of the station.