Shortly before the BBC sold its Outside Broadcast division to SIS, the broadcaster upgraded its Calrec Sigma digital audio consoles onboard two of its vehicles — the Unit 2 and Unit 12. The upgrade involved the installation of Bluefin, providing 320 channel processing paths and enabling the Sigma consoles to tackle larger productions that would previously have required a more powerful desk. These can be configured for up to 52X full 5.1 surround channels.
Both vehicles now form part of the SIS fleet, and these console upgrades support the broadcaster's commitment to provide first-class facilities for HD broadcasting. Unit 2 and Unit 12, which record sports and entertainment programs, are now fully HD- and 5.1 audio-capable.
Eyes and ears
As part of the planning process regarding the console upgrades, we compiled a list of other equipment that would be needed to deliver 5.1 audio. One definite requirement was accurate audio metering that would effectively monitor both vehicles' increased surround-sound capabilities.
After looking at a number of possibilities, we chose the DK-Technologies MSD600M++ audio meters for their JellyFish and StarFish display technologies. These present both stereo and surround-sound images in a logical and intuitive way, making it easy for engineers to instantly see what's happening to the audio signal.
The meters first came to our attention three years ago when we saw one demonstrated at IBC. We were fascinated by the technology because of its ability to marry the eye and the ear together. When monitoring complex audio signals, it is helpful to both see and hear what is happening. This is particularly important in the OB environment, where broadcasters are under pressure to capture a live event and get it right the first time. With so much going on, it is vital to have metering that tells you at a glance what the signal is doing, even if it is just confirming what your ears are already telling you.
Efficiency straight out of the box
Two MSD600M++ meters were delivered shortly before the start of Wimbledon 2007. For that particular event, Unit 2 covered No. 1 Court, and Unit 12 covered Centre Court, both broadcasting in HD with 5.1 audio, using pre-Blufin desks.
The meters arrived in boxes, and our first issue was finding space for them on top of the consoles. Space is always at a premium in an OB truck, and ideally the meters needed to be mounted in the console panel. The current audio desks are being modified to accommodate them. However, when the audio meters first arrived, we had to make do by sticking them to the front panel with Velcro. This was important because they needed to be within our line-of-sight.
Both meters worked straight out of the box. All we had to do was plug them in and decide which audio feeds to link them to. Some of the digital feeds were not being used, so we adapted those for the meters. DK-Technologies' UK representative, Andy Page, assisted with the installation and gave a quick demo. This was helpful, but interpreting the display and linking that to what we were actually hearing involved a steep learning curve. The software is quite intuitive, and the SIS team has subsequently found a useful PDF on the company's Web site that explains how to interpret the various display patterns.
Having the audio meters onboard the trucks when broadcasting the 2007 Wimbeldon made the job easier. The displays show the energy content of all the channels on the screen. Phase errors in individual vectors are highlighted in red, so they are easy to spot.
However, JellyFish and StarFish alone are not accurate representations of absolute level. The meters have bar graphs that provide this information, but they are quite small and can be hard to read when you are working under pressure. To get around this, we used conventional PPM meters configured in stereo, with the ballistics relevant to live broadcast. The MSD600M++ also offers this facility, as you can choose the manner of all the different metering options. The drawback is that you can end up with too much information, which is confusing if you are trying to see what is happening in one quick glance.
The unit is flexible and gives many different metering options and modules, including analog, AES3 and SD-SDI formats. It supports all surround formats and accepts up to 32 input channels, with four configurable input slots and four output slots. A lot of phase information is wrapped up in the display, but the more production teams use it, the more they learn how to interpret it.
Since installing the meters, SIS has learned that they can also be used to control a matrix of up to 48 inputs and 48 outputs, which could help pick up monitoring sources and switch between them. The latest software release incorporates Black and Lane's Ident Tones for Surround (BLITS) tone generator. SIS has a separate box for this, but it is likely that future metering purchases will combine both functions in one unit, thus saving valuable space onboard the trucks and possibly cutting costs.
Calm in a pressurized situation
Delivering live, high-quality 5.1 audio in an OB environment is always going to be pressurized because you only have one chance to get it right. Often engineers only glance at audio meters because they don't have time to sit and study them. The audio meters become really useful when an engineer hears something odd, particularly in a fold-down situation where he or she is monitoring the desk. Looking at the MSD600M++ and seeing that tell-tale red outline in the JellyFish display helps confirm that something isn't right phase-wise. This capability enables the engineer to correct the issue before it became a real problem.
Since installing DK's meters, the BBC — and subsequently SIS — has used them to monitor audio signals at a variety of events, including the Proms broadcasts and Glastonbury Festival, both of which were broadcast in 5.1 surround.
Andy Payne and Bill Whiston are sound supervisors for SIS Outside Broadcasts in the UK.