Distribution
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Testing mixed signals by Paul Nicholls, PHABRIX I t is fitting that a lot of the avid (read trapped) readers of this article are broadcast manufacturers flying over the Atlantic to NAB in Las Vegas so I have a captive audience to influence with an open invitation to come and visit us in the North Hall N5015. Whereas the new product range has been designed for applications in traditional settings such as engineering bays, OB’s and Studios, some of the unique attributes of the PHABRIX Rx range on show at NAB are very much targeted toward broadcast manufacturers. Hence the appeal I hope to the passengers attempting to drink the flight dry once again. (Only joking seat 51H). This magazine issue deals with distribution within the broadcast infrastructure. The complexity and variety of signal sources involved in broadcast is of course a broadcast engineer’s nightmare. Usually this involves large investment, a variety of testing equipment from different manufacturers, different interfaces, support issues and let’s not go near ROI. This is where the Rx platform is set to perform. of program configurations at both 16 and 20 bit. Metadata can be altered with adjustable starting frame rate and output as AES or embedded if required. The accompanying Dolby E analyzer can be set to check the metadata using colour identified fields. 8 channel audio metering and guard band analysis with comprehensive logging make up the toolset. In combination these features provide a manufacturer’s dream toolset - closed loop testing and with support for Dolby D and D plus in the near future. This audio testing capability in combination with video support makes the Rx a very powerful solution. Up to this point the video signals considered have been uncompressed and it is here that the new modules now under development within PHABRIX move into a new technological domain - support for ASI and IP. ASI is an established technology particularly in cable and satellite installations. Usually these installations offer content management services from select teleports for program origination of television programs. MPEG2 is the predominant format currently in use however support for H.264MPEG4 is on the increase particularly with ad-hoc contribution from newsfeeds and specialised sporting events. At the headend ASI meets SDI and having the ability to monitor both in a single product is a focus of our technological demonstration at NAB. Before the editor is condemned for allowing a gratuitous PHABRIX commercial, let’s look at those signals being distributed and the way in which the PHABRIX instruments can be deployed by manufacturers with an emphasis on several new technologies supported by the range - Dolby E, ASI and IP. There should be a little murmur at this point for rarely do such ‘mixed signals’ appear together in a single cost effective solution. Video signals Video signal support from simple SD-SDI to the more complicated HD-SDI and dual link through to 3G-SDI Level A and B is available in both generator and analyser modules. Support for different colour spaces 4:2:2 YUV, 4:4:4 RGB, 4:4:4 YUV, at 10/12 bit has increased the variety of signals to over 350 different formats. Within the signal the video status is analysed with EDH (Error detection and handing) and CRC (cyclic redundancy check sum). Signal identifiers are also present in DID displays which can identify the multitude of signal data present. Cost effective physical layer measurements as a verification of signal integrity has also been a significant PHABRIX development. Audio support is in the form of embedded audio and AES. At NAB a new feature set is available which provides both Dolby E bitstream generation and Dolby E bitstream analysis. Dolby E has become a de-facto standard enabling surround sound and requires a particular set of T&M instruments. The new Dolby generator provides a full range 68 | TV-BAY MAGAZINE As a first step into test and measurement for compressed video signals PHABRIX will be demonstrating full decode of MPEG-2 and H.264 video sources integrated into the Rx platform at NAB. Currently supported video formats are: • 525i59.9 and 625i50 • 720p25, 720p29.97, 720p30, 720p50, 720p59.94, 720p60 • 1080i50, 1080i59.94, 1080i60 • 1080PsF23.98, 1080PsF24, 1080PsF25, 1080PsF29.97, 1080PsF30 • 1080p23.98, 1080p24, 1080p25, 1080p29.97, 1080p30 In addition to the decoded SDI output signal monitoring as defined in ETSI TR 101 290 level 1, 2 and 3 will also be available.