ALEXANDRIA, VA.
Whether working in a post production house or a broadcast facility, technicians have to analyze video from a multitude of formats and a range of equipment. The challenge, however, is always the same—to measure the particular properties of both video and audio signals and adjust them so the final product is of the highest quality. Equally important, is the ability to guarantee that the products meet legal luminance and color limits regulated by the FCC for over the air broadcasters.
Testing video signals directly from source material is only one of the jobs of broadcast test and measurement (T&M) equipment. Test signal generators, in conjunction with measurement devices, are used to ensure that the signal paths throughout a plant are able to carry a video signal through a desired path without degradation or loss of any element in the original signal. With the migration of many broadcast facilities to file-based workflows, a need for a new level of testing has emerged; the ability to analyze video in file format as well as its transport within an IP stream.
In today's marketplace, there are products that can provide almost every quality control function needed to manage video from creation to transmission and distribution. These devices and software options broadly range in price, features, and accuracy. Choosing the correct solution requires a close inspection of the needs of the application in order to determine which device(s) will achieve the end goal most cost-effectively.
Wohler Technologies Touchstone 3GPOWER IN THE PALM OF YOUR HAND
Handheld test signal generators and signal measurement devices are good examples of the breadth of choices available in choosing a T&M device. Used primarily for testing new or existing signal paths, these devices offer portability and features once only found in larger rack-mounted units.
Wohler Technologies in Hayward, Calif., long known for its audio test equipment, is out this year with an inexpensive handheld video and audio test signal generator. The Touchstone 3G has 37 different digital test signals for everything from 480i to 3G, according to Wohler CEO Carl Dempsey.
"The development of the Touchstone palm-sized digital video and audio test signal generator came out of our Penpal line of pen-sized generators," he said. "Users wanted both SD and HD signals in a single device, so we developed the Touchstone."
Harris' GEN-STAR is a larger handheld unit with touchscreen control and added features such as a video and audio delay test signal as well as an external reference input. These features might come in handy when troubleshooting signals within a production facility.
UK-based Hamlet Video International Ltd. has a handheld device that—while more than twice the size of the Touchstone—serves as both a test signal generator and a video and audio monitor. The company's FlexiScope and MicroFlex handhelds operate for more than two hours on 6 AA batteries and provide waveform, vector and audio analysis of SD and HD-SDI signals. These handheld units are unique in that they can be purchased with various I/O modules depending on the user's format needs and budget.
"With 3Gbps EYE patterns down to analogue composite," said Steve Nunney, managing director of Hamlet, "our new products feature modular construction enabling the client to choose what they want when they want it."
For users who want everything in a single handheld unit, U.K.-based Phabrix has one of the most impressive and feature rich handheld units on the market. Distributed in the United States by Leader Instru-ments in Cypress, Calif., its SxA test generator and handheld scope can generate and test every signal from analog composite to 3G HD-SDI. It can even generate a signal output and simultaneously take in a return and test that same signal. The screen is the same high resolution one used in Sony's PSP game units and has a rubberized jacket, making for a sturdy field unit.
Tektronix WFM5000 is a portable Waveform Monitor with support for HD and SD SDI and format auto detection. For portability and accuracy, the Tektronix WFM5000 offers all the technical accuracy of Tek's rackmount scopes in a portable configuration. "The WFM5000 has the richest display on a portable device in the industry," said John Hammarstrom, senior marketing manager of video testing for Tektronix in Beaverton, Ore. The display allows for multiple views of information not always available in a smaller handheld unit.
ACCURACY & OPTIONS
The traditional high-quality green and amber phosphorscopes that are always found in critical locations in a broadcast plant are now more feature-rich than ever before. "In the past 12-24 months our customers have been asking for better control and management of the process, and features that extend to the operators as well as the engineers," said Hammarstrom.
Tektronix is known for the accuracy of its signal measurements and display. The company's current high-end scope, the WFM7000, provides a full range of signal analysis for SD and HD-SDI signals. "The familiarity of our boxes with freelance crews can be a benefit for any facility," said Hammarstrom, who adds that the company will release a new hardware platform that includes 3G eye measurements this fall.
Another familiar name in precision video scopes is Harris' Videotek line. They tout their TVM4DG as the "most cost-effective HD/SD test and measurement product on the market." As a drop-in replacement for older analog or SD Videotek scopes, this unit is a good general-purpose scope providing multiformat waveform and vectorscope readings with Videotek's patented timing feature.
Like Tektronix and Videotek, Leader Instruments offers many configuration options in its LV5800 multi-monitor platform. From a full color XGA TFT, its scopes can view signals from SD to dual-link HD. Options include Dolby monitoring and Ethernet connectivity for remote monitoring. All three manufacturers offer such an extensive list of option modules and software packages that the only way to determine the best solution is to thoroughly assess the needs of the monitoring operator prior to approaching vendors.
MEASUREMENT FOR ALL BUDGETS
As more and more control rooms move to multiviewer and LCD-based monitoring solutions, rasterizers that provide measurement meters via a single monitor output have become even more popular. Originally just used for confidence or operations monitoring, rasterizers have evolved in quality and clarity to make them close competitors to the traditional monitor in frame video-measurement tools.
For master control and on air operations, a rasterizer such as the Tektronix WVR7000, "is an excellent solution for monitoring Gamut and color compliance required by the FCC for terrestrial broadcasters," said Tektronix's Hammarstrom. The size of the display and multitude of easy to read measurement options can provide an operator all the information necessary to monitor the quality of the signal on a single monitor. Tektronix calls its measurement windows "tiles." These are user configurable sub screens that can provide gamut, luminance, color phase, jitter, eye and most other popular scales needed to quality control a video signal.
Leader Instruments and broadcast conglomerate Harris both provide similarly configurable systems with their LV7700 and VTM4100 models respectively. Choosing among the three major manufacturers often comes down to choice of scales and user interface. Each manufacturer has its own patented features; whether Harris' video relative timing display or Tektronix diamond and arrowhead gamut meters, each has subtle differences that might offer needed clarity of measurement or familiarity of operation.
Blackmagic Design, a newcomer to the broadcast test and measurement sector, introduced Ultrascope at NAB. A newcomer to the field this year is Australia-based Blackmagic Design, which will begin selling its 3Gbps rasterizer, the UltraScope, for only $695. The UltraScope is a software-based solution with a PCI-Express I/O card that can be installed and run on a local or networked PC.
"This is unlike any other product we have developed in the past," says Blackmagic Design Founder and CEO Grant Petty. "Our design goal was to produce a true broadcast strength product that includes innovative design and features that broadcasters demand, one that is offered at an affordable price; and that would appeal to smaller studios."
TESTING THE ESSENCE
In the arena of MPEG monitoring, there are several products that broadcast and production facilities should explore.
Pixelmetrix of Singapore, offers the DVStation, which connects to "virtually any kind of RF, serial or IP interfaces, which provides operators with complete visibility of content as it travels through the transmission chain," said Pixelmetrix president and CEO Danny Wilson. "Television broadcasting has gotten a lot more complicated; budgets and staffing are spread thin, yet operations are challenged with offering more channels across multiple platforms."
Munich, Germany-based Rohde & Schwarz also offer an MPEG-2 and MPEG-4 transport stream analyzer, the DVM400, which, according to Video Product Manager Bob Ellis, "can analyze the quality of transport stream-fed video in real time." With the TVScan software option, users are able to run reports of the quality of the signal leaving the transmitter.
Why is monitoring MPEG streams and transmitter output so important? According to Ralph Bachofen, vice president of sales for Triveni Digital in Princeton, N.J., such tools can be used for both troubleshooting and compliance. "Using our StreamScope, a broadcaster can not only receive alarms for issues in the transport stream, but a comparative test can be run on the signal leaving the facility and those returning either via off-air or cable." This could allow a broadcaster to put a QoS measurement limit into its carriage agreement with a cable or satellite company and be used to flag when the quality fell below acceptable levels.
Never before has there been a broader range of tools available for use in managing facility video signals. These include handheld units that an engineer can use to track down an attenuated signal path, to sophisticated tools that can save money and keep a station operating within legal broadcast limits. The best news of all is that prices keep coming down as features and operations simplicity continues to be on the rise.
