Testing mixed signals

Will Strauss#

Author: Will Strauss#

Published 1st May 2012


It is fitting that a lot of the avid 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.
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 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.
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.
I’d just like to say a few words at this point with regard to a condition known as acronym hell - the desire for engineers and technologists to wrap as much detail as possible into a minimal word count. Getting to grips with such acronyms as PCR, PID, ETR, TDT, CAT, PES, EIT, and MDL etc. has been ‘interesting’. I must admit that I thought the world had gone completely mad when I replied to a transport stream customer with a reference to ‘T&M’ and he actually asked what it meant!
The important point here is that within a 1U half rack or 2U space, a truly multi signal toolset is now available and seeing this in action rather than reading about the seamless way the different toolsets are employed are best viewed on the stand. I’m happy to add the incentive of a free mouse mat for those of you who have read down to this part of the article and visit us at NAB.
Alternatively if you’re not reading this on the plane and would still like a mouse mat please drop me an email at paul@phabrix.com and I will unashamedly bribe you with a visit from our sales team.
www.phabrix.com

About:
The PHABRIX Rx is a modular rack mount solution with the ability to accommodate up to four option modules supporting up to 8 simultaneous SDI channels. Different chassis types ranging from a 1U rack rasterizer through to a 2U dual screen instrument with audio monitoring are available for different applications and budgets. The module slots can be configured to target a particular testing requirement be it video or audio, compressed or uncompressed and associated signal types. Instruments on each module can be controlled independently and the output screen of each instrument delivered via front panel interface, HDMI or SDI output. All chassis provide a multi-viewer of instrumentation on an external monitor at 1920 x 1080. Remember it can accommodate up to 8 simultaneous SDI channels or 8 optical if required so the appeal for the broadcast manufacturer is considerable, particularly when controlled remotely with extensive logging. With a single chassis control centre the addition of more modules rapidly reduces the capital cost per signal.

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