The importance of maintaining digital audio paths


Larry Schindel TV-Bay Magazine
Read ezine online

A portable, handheld, digital audio stream analyzer/generator is an essential piece of test equipment in the broadcast environment. It allows engineers and system integrators to quickly monitor and verify the composition, and integrity of, audio signals at any point from production all the way through the distribution chain.

While the process of testing and troubleshooting audio systems is not new, it is important to employ a solution that supports multiple audio formats, such as PCM and Dolby

® encoded bitstreams, and includes modern interfaces. This allows it to be used everywhere in a broadcast, cable, satellite, or post production facility, and even to verify the signals received by the viewer's home theatre system. A device that enables testing in all these environments is as useful to an audio engineer as a digital multimeter is to an electrician.

The Linear Acoustic® MT2000 Multichannel Bitstream Analyzer is one such solution. It accepts signals via AES, 3GHz SDI, MADI, and DVB-ASI* interfaces, and even supports TOSLINK optical and HDMI* consumer connections. The unit identifies the format of the selected input signal and when appropriate, activates the built-in Dolby E, Dolby Digital or Dolby Digital Plus decoder.

Analysis capabilities include error detection at the AES3 layer and within the coded audio layers, including SMPTE 337 formatting information and Dolby E guard band position. Display of the full set of bitstream configuration and metadata parameters contained within Dolby bitstreams is also a standard feature.

In addition to displaying audio signal statistics and metadata, the MT2000 includes ITU-R BS.1770-1/2/3 loudness measurement with selectable Dolby Dialogue Intelligence to support ATSC A/85 and EBU R128 measurements.

User configurable alerts are supported to monitor for conditions such as: the loudness measurement being either over or under a threshold, the center channel measuring too low, which indicates a possible loss of dialog, silence detection, loss of reference, or other stream error conditions.

The MT2000 is capable of generating two-channel PCM test signals with a user-selectable output waveform type (sine wave, white noise, pink noise, or frequency sweep), amplitude, and frequency. In this mode, the amplitude and frequency of each channel is independently adjustable. Test signals and analysis are also provided for latency and basic lip sync. Basic video signal generation is included as well to support creation of SDI output streams and lip sync testing.

Additionally, an extensive set of useful Dolby Digital, Dolby Digital Plus, and Dolby E test bitstreams is stored internally. The MT2000 can output the selected test signal or bitstream simultaneously on all output connectors, even while receiving and decoding an input signal. Signals are output simultaneously to the AES and TOSLINK optical connections and can be re-embedded into any of the SDI pairs. The output can be the original input signal, a PCM decoded version of the input signal, test signals, or, in the case of the SDI or MADI outputs, a combination of all of these. Inputs can be used as sources for embedding even if not used for decoding, thus channel shuffling can be easily accomplished. A bright yellow OLED display and integrated rotary encoder/joystick provides straightforward menu navigation and parameter adjustment. A standard 1/8-inch stereo headphone jack can be switched to monitor any two channels or a downmix of a decoded Dolby signal. A digitally amplified speaker provides a surprisingly loud output useful for quick checks and for emulating sound systems found in portable devices.

A recent software update adds support for several new features including: EBU R128 loudness measurement mode, multichannel PCM input support, and a 16-channel "discovery" mode. This mode simultaneously displays all of the audio channels contained in a SDI stream or the contents of a MADI stream in groups of 16. Additionally, a completely new menu structure significantly streamlines and eases operation.

The MT2000 is powered by an internal NiMH rechargeable battery pack or from its DC power port via an included universal power supply. It ships with a carrying case and multiple adapters.

* DVB-ASI and HDMI support is optional


Tags: iss111 | linear acoustic | dolby | aes3 | mt2000 | dvb-asi | toslink | smpte 337 | Larry Schindel
Contributing Author Larry Schindel

Read this article in the tv-bay digital magazine
Article Copyright tv-bay limited. All trademarks recognised.
Reproduction of the content strictly prohibited without written consent.

Related Interviews
  • Linear Acoustic at IBC2011

    Linear Acoustic at IBC2011

  • The Telos Alliance at IBC 2016

    The Telos Alliance at IBC 2016

  • 7.1.2 Dolby Atmos support by Halo from Nugen Audio at NAB 2017

    7.1.2 Dolby Atmos support by Halo from Nugen Audio at NAB 2017

  • Dolby at IBC2011

    Dolby at IBC2011

  • Phabrix RX series at IBC 2014

    Phabrix RX series at IBC 2014

  • TSL at NAB 2012

    TSL at NAB 2012

  • Phabrix at BVE 2012

    Phabrix at BVE 2012

  • Sonifex at BVE 2012

    Sonifex at BVE 2012

  • Phabrix at IBC2011

    Phabrix at IBC2011

  • AES3 to Dante / AES67 converters from Glensound at NAB 2019

    AES3 to Dante / AES67 converters from Glensound at NAB 2019


Related Shows
  • Show 20 - July 17th 2013

    Show 20 - July 17th 2013


Articles
Undercover Remote Production
David Bradley

It’s only taken 20 years and it seems that Remote Production is finally coming of age, but it now requires far more cameras than anyone envisaged back in the last century!

The move to remote production is one of the unstoppable trends of 2019 and moving into 2020. Our CamBall cameras pioneered remote working as early as 2003 with sport and wildlife programming using remote production for many years with incredible results.

Tags: iss139 | ptz | br remote | 5g | remote camera | atlantic productions | camball | camball4 | David Bradley
Contributing Author David Bradley Click to read or download PDF
The Future of Broadcast Connectivity
Jamie Adkin The use of KVM equipment has been essential to meet the evolving needs of the broadcast industry for many years. Over that time, many in the industry have recognised the importance of using IP-enabled KVM to break down technological barriers and enable real-time access to visuals wherever and whenever they’re needed. These components are vital parts in live production environments in particular.
Tags: iss139 | adder | kvm | ip kvm | Jamie Adkin
Contributing Author Jamie Adkin Click to read or download PDF
The LED Lighting Revolution
Neil Vann Back in April 2019, the National Association of Broadcasters hosted the annual NAB show in Las Vegas where over 90,000 people from more than 160 countries came to see the latest broadcast technology from around the world. Honouring the highlights of the show were NAB’s 2019 Product of the Year awards, where the newly launched Chroma-Q Space Force onebytwo – a bright, tuneable white LED softlight with a high CRI, TLCI and TM-30 - picked up one of these prestigious awards in the lighting category.
Tags: iss139 | ac-ent | led | lighting | chroma-q space | softlight | studio force phosphor | Neil Vann
Contributing Author Neil Vann Click to read or download PDF
Making Metadata Work
Bruce Devlin - new I dare say that if you’re a keen reader of my column then you will be brushing up on your Dutch pronunciation and acclimatising yourself to mayonnaise on your chips rather than ketchup. If you’re really keen then you’ll also be making sure that you practise your Dutch jokes about the Flemish to ensure you don’t accidentally tell a Flemish joke about the Dutch at 2am on Sunday morning in a local bar somewhere near the red light district in Amsterdam.
Tags: iss139 | metadata | class | mrmxf | ibc | mesa | Bruce Devlin - new
Contributing Author Bruce Devlin - new Click to read or download PDF
The University of the Third Age
Bernard Newnham Here's a cliché - "We all get to be old one day - if we're lucky". There comes a point when things like "....mastered in Dolby Vision Domestic and SDR Rec 709....." become just a touch unimportant (and actually I never really understood that stuff in the first place). I retired for the third time last year - BBC producer, and before that cameraman, then freelance producer, trainer, do-your-own camera, sound, editor, blah blah, then 11 years university teaching. I did my bit - never a BAFTA, but certainly the first into a good few things - but it all has to come to an end sometime.
Tags: iss139 | u3a | panasonic | davinci resolve | Bernard Newnham
Contributing Author Bernard Newnham Click to read or download PDF