Things are changing quickly with respect to technology and applications when you consider all of the developments in the world of video compression. New codecs and transmission technologies are offering some interesting opportunities for many broadcasters and network operators—and at the same time creating great challenges for their engineering and support teams. MPEG test & measurement equipment purchases can be a technology challenge. Some organizations have buying cycles that are long enough to outlast the latest technology development.
Whether you’re talking about managing HD transmission in your newly upgraded and expanded TV facility; the use of IP protocols to distribute (non real-time) or transmit (real-time) over an IT infrastructure; or monitoring of RF signals in your transmission scheme, you are faced with a wide variety of options when it comes to T&M solutions.
There are few considerations that warrant closer scrutiny than capital investment in tools that potentially could have a short usable life because of the fast pace of technology.
Just consider today how many of you are dealing with PCs as an operational expense rather than a capital purchase. It wasn’t too long ago that PCs were a capital expense with a three year depreciation or longer.
Keep this in mind when you start the justification process for new MPEG T&M equipment. Extensible platforms and manufacturers with a proven track record of providing timely support for new and emerging standards are important when thinking about ensuring a long-term return. It’s important to think of potential vendors in terms of a business partnership—they will have a critical impact on your success as you roll out new technologies and services.
MPEG Test & Measurement Application Focus
There are three primary areas of application focus for MPEG T&M tools that should be considered based on your specific needs:
- Design Certification & Compliance Testing
- Technical Monitoring, Installation & Maintenance
- Real Time Confidence Monitoring
The first of these categories deals primarily with equipment manufacturers that make devices that rely on compressed video. These devices include set-top boxes or mobile appliances like cell phones or PDAs. We will leave the components of that discussion to another article.
This article will illustrate some of the key evaluation areas in both of the other application categories for MPEG test and measurement.
Technical Monitoring, Installation & Maintenance
Long term reliability starts with the installation of infrastructure. The technologies required to deploy, monitor and maintain digital television services are very complex. As you devise more sophisticated service offerings for your audience the combination of skills required to maintain a competitive edge can add significantly to the cost of staying in the game.
Many organizations don’t have the depth and breadth of expertise to put an MPEG engineer in front of every problem that arises. When deploying new services, putting a new piece of equipment (a codec for instance) into service or chasing down an elusive intermittent fault, your ability to act quickly and effectively has a direct impact on your company’s profitability.
Some tools today specifically enable you to empower support personnel with the ability to set up an analysis tool, trigger and capture data (video) based on pre-set parameters, analyze and debug a problem. Your engineers can be used to define the parameters, review the results and not spend so much time waiting and watching in anticipation of a failure. When a tool provides information, not just data, it can enable a broader population of your technical staff. As a result it can reduce your engineers’ time to insight. The quicker the source of a problem can be identified, the quicker a resolution can be defined and implemented.
Whether your technical team is installing a new service from the ground up, introducing a new piece of equipment to the video and audio stream in your facility or faced with a particularly difficult maintenance problem, your job is to help them work as efficiently as possible.
Real Time Confidence Monitoring
Every facility’s long term goal is to move from reactive monitoring—where engineering staff fix a problem once it occurs, to predictive monitoring—which gives warning of incipient failure and time to fix the issue before it becomes a major problem.
There are a lot of technical parameters to be monitored in a digital transmission facility if you want to protect yourself from the digital cliff. As a digital signal deteriorates, it approaches a point on the performance curve when sudden and catastrophic failure can occur. It can drive your viewers to seek more reliable, higher quality signals.
Many of the symptoms that precede the failure aren’t visible in the transmitted image. It just appears that you’ve driven off a cliff.
In a digital transmission facility, there are many contributing factors, dozens of technical parameters and a variety of physical layers to be concerned with. One has to worry about the quality of the video when received and ingested into the facility’s systems as either baseband or compressed material. Once in the system it is switched, converted, compressed, manipulated, edited, uncompressed, mixed and muxed. It can come in via microwave or tape and likely is sent via RF at some point in its travels.
That’s a lot for your technical team to watch. It probably means that they need to be in a lot of places during the day. If things start to go wrong, it might mean that they need to be in several places at once.
There are several significant features in confidence monitoring tools that should be given careful review as you upgrade, expand or replace your current monitoring elements.
The first is a solid technical review of supported standards and formats. Several technical parameters require real-time high-reliability 24/7 monitoring and others require long-term trend analysis of both RF and transport stream parameters.
There are some basic compressed video measurements that need to be watched and managed on a real time basis such as PCR timing, continuity count errors and PSI/SI/PSIP content and repetition rates which should be monitored 24/7 by transport stream monitors. A key tool for PSI/SI/PSIP content monitoring includes monitoring of time defined reference templates against which the actual transmitted system information can be compared.
Monitoring at all levels and all formats of the transmission network provides key performance indicators to the health and long term stability of a network. Trend analysis of PCR accuracy, arrival interval and drift are key to proactive preventative monitoring.
Another important thing to keep in mind as you review MPEG T&M tool purchases is that the technologies required to implement compressed video transmission solutions enable a very sophisticated, complex and often geographically widespread implementation. The impact on the compressed signal quality and eventual delivered signal quality from the other physical layers in your plant shouldn’t be underestimated. With this in mind, your MPEG T&M tools become one important element in what has become a multi-format multi-layer environment.
Multiple engineers need to have simultaneous access to their T&M tools remotely and those tools need to be configurable as part of a multi-layer solution. This implies support of a web-based interface and data access via SNMP or other suitable protocol.
Your T&M vendor should be prepared to provide technical support, white papers, training tools and seminars to help educate and keep your engineering staff technologically current. You should be able to count on them as a partner in the process of new technology roll out.
Jon Hammarstrom is the senior manager of video global field marketing for Tektronix.
