The Transition To Digital

Publish date:

The Transition To Digital

May 1, 2001 12:00 PM, By Chriss Scherer, editor

How digital is your facility? For most stations, the transition began some time ago. A few have resisted the change and are still holding on to as much analog as possible. In time, all facilities will install digital equipment � mainly because most of the analog equipment is disappearing. In most equipment cases, some type of digital replacement already exists. Perhaps the best way to consider the situation is not to think about if you will have a completely digital facility, but when you will have one.

It's probably safe to say that every station has a piece of digital equipment. With so many high-quality consumer formats available � such as CDs, DATs, MiniDiscs, MP3s � there is bound to be something digital in use. Let's start with a clean slate and move forward from here. Where do you begin?

Start small

I don't think any facility is immune from gradual equipment additions. When minor facility modifications are required, there is usually a need to add the associated audio and control wiring. This is the easiest and best place to begin. A well-planned facility has an established wiring and wire-type standard. If yours relies on non-digital-ready wiring, make the change now. The cost of wire capable of high-speed data and digital audio is not much more expensive than its analog counterpart. What's better is that digital wire and cable is the best analog wire you can get. Digital wire must meet specific criteria for data; criteria which easily cover analog applications.

Professional digital audio equipment uses the AES3 digital audio standard. AES3, the balanced signal standard, also has an unbalanced version, AES3-ID. The data information is the same. The difference is the characteristic impedance (110? for AES3 and 75? for AES3-ID) and the signal voltage. One or the other should be chosen for the house standard. If necessary, converters are available.

The standard also supports different sampling rates. It is best to select one standard for your facility and stick with it. Avoid converting signals as much as possible, as this creates such problems as overshoot. Once the infrastructure has been upgraded, upgrading the audio equipment is a simpler task.

Digital audio storage and playback systems and digital editing workstations are inherently digital. Connecting these devices to other equipment can be done through analog or digital connections, but digital connection provides greater functionality.

Digital connectivity between all the devices allows you to consider the entire facility as a single entity. When the consoles, audio routers, automation systems, DAWs and other equipment can communicate, audio can pass through the system, but so can program-associated data (PAD). While the current analog transmission system does not provide a practical method of including PAD, Internet radio and IBOC do. (Analog FM has RBDS, but there are not enough stations fully utilizing it, nor are there a significant number of RBDS receivers in consumer use.) A digital facility also shifts the design of the studio facility from an audio-based facility to a data-based one.

The integration of consoles and routers has continued its evolution. In multistation facilities, this approach offers savings in several areas. By locating all the audio engines in one room, the audio wiring needs are dramatically reduced. Cable preparation, a major part of the labor required to construct a facility, is reduced, resulting in a time and labor savings; labor that can be used in other areas.

From hear to there

Because the United States does not yet have a digital radio transmission standard, each station's transmission facilities are likely in very different states of technology. The audio processor, really part of the audio chain, is the most sensitive issue in a station. Creating a signature sound is a personal goal for many people. The debate between an analog or a digital processor is one that is best saved for an entire afternoon. As far as the transition to digital is concerned, completely digital, and even digitally controlled analog, processors provide stations with a means to create, modify, store and recall preferred settings. As the facility migrates toward being completely digital, the processor can fit into this �total facility� method.

Digital studio-to-transmitter links (STLs) can be wired or wireless. Most offer greater bandwidth than their analog predecessors. The wired versions typically provide a bi-directional path, which works well with audio sources located at the transmitter site, such as satellite feeds and RPU receivers.

Since an IBOC standard is not ready, there isn't much replacement that stations can do to continue the transition, but stations can take preparatory measures. The BE Radio October 2000 cover story discussed some of the costs that a station can expect. These costs can extend to just more than $40,000 or more. What about stations that need to replace facilities today? You can't buy an IBOC transmitter, but you can buy one that will likely be able to handle an IBOC signal. While some of the specific details are resolved and methods refined, the safest approach for a transmission system is to allow greater headroom than you would for analog. This sounds vague, but each application will be different. The best advice is to talk to your transmitter manufacturer. IBiquity Digital also offers an evaluation to stations as part of the iBiquity EASE program.

Rebuild or replace?

A long-term facility plan should exist as part of a station's capital plan. This will dictate which approach is best for the station.

Stations planning a new construction should future-proof as much of the facility as possible. There are many unknowns, but current-trend observation can guide you very well. Plan enough physical space for the continuing increase of computers. Studio furniture should be able to handle additional monitors and possibly house more computer cases. Don't forget to consider the additional airflow and noise suppression. Rack rooms and server areas will require additional space. �Add another PC� is often the answer given when a new need arises.

In a new installation, the wiring plan should be digital ready. AES3 and CAT5 cable (or better) should be used. It is also likely that house sync signals will increase usage, so an extra coaxial cable should be added to each room.

The integrated router approach allows you to design the entire facility as a single system. This design can be fulfilled with separate system components or a complete package. Be sure to consider any file-sharing needs. A fully digital studio router does not only route audio. Information from DAWs, automation, music scheduling and traffic systems, and other sources can be shared and used.

For facilities that are not planning a complete change, the transition can be made incrementally. By starting with a few key pieces of equipment, the financial load can be distributed over time while the benefits of the change can be realized.

Photo of WLTW-FM on page 36 by John Farrell and courtesy of Meridian Design Associates.