This page contains a Flash digital edition of a book.
special report test & measurement

With NAB very much on the horizon, it is time for a manufacturer like Hamlet to consider what the current challenges are facing equipment purchasers. What are the projects on the table, and what, therefore, are the implications for test, measurement and quality control? Hamlet’s Steve Nunney reports.

Challenges for the broadcast

engineer

A

s I see it, there are two big issues at the moment. In conventional linear signal routing there is the need to support 3Gb/s infrastructures. At the

moment it is not clear if this will be used for 1080p high definition or to accommodate the two streams of stereoscopic 3D television, but 3Gb/s is very definitely important. The second concerns the moves away from linear signals altogether, to connect production sites and broadcasters with IP networks and to store content as files. This, too, has an implication for quality control. Taking the first point, it seems likely that future installations will be laid out with 3Gb/s in mind. Despite the promises of many vendors, there is not that much 3Gb/s equipment available yet, but it does make sense to cable with it in mind, to minimise the complications of implementing it. The difficulties of cabling for 3Gb/s are now generally known. Put simply, you have what is in effect an RF signal going down co-ax cable, which is extremely susceptible to

attenuation. If you put a sharp bend in a 3Gb/s cable, the signal is likely to want to go straight on, causing a big drop in effectiveness.

That sharp bend even on premium cable is also likely to change the capacitance of the co-ax at that point, and again this is likely to be significant. Pulling a cable tie tight will also cause the same problem. So, too, will be forcing just one more cable into a tray.

Digital signals, of course, suffer

44 l ibe l march/april 2010 l www.ibeweb.com

Steve Nunney.

from the cliff effect: they either work or they do not, and you get no warning of impending failure. So laying in a cable and checking that there is signal by plugging it into a monitor tells you nothing. You have to know how robust the digital signal is, how sharp the edges on the transitions between high and low. The preferred way of doing this is with the eye pattern: an overlay of multiple digital transitions on the test device. If the edges are sharp, the highs are high and the lows are low, you will see a clear eye in the middle of the display. If the eye is clouded by traces running through it, you know that the signal is not robust enough to rely on.

Hamlet’s MicroFlex - the smallest of handheld devices designed to get into the back of the rack - includes the capability of both generating and testing digital signals, as even the technically difficult 3G eye pattern is included.

Remember that the problem is as likely to be the cable itself, and its topography, than any piece of equipment. So pulling the cable out of the rack and into an oscilloscope on a trolley tells you very little. You need to get the test device to where the cable goes, not the other way around. That is why the low cost, award winning Hamlet MicroFlex - the smallest of handheld devices designed to get into the back of the rack - includes the capability of both generating and testing digital signals, as even the technically difficult 3G eye pattern is included. For those looking to migrate away from co-ax, a fibre I/O module will also be available soon.

The more challenging migration, though, is from linear, video specific connectivity to a file-based architecture. The benefits are many, but one of the most significant is that

it frees the delivery systems from the tyranny of real time. Content can be delivered as a file from anywhere, at a speed that is dictated by the IP circuit - maybe faster than real time, maybe slower.

In the past content has arrived at a broadcaster on tape, to be ingested into the system as a quality control operator checks it for technical conformity. With no need to ingest in real time, forcing it to happen just for a QC check is a big bottleneck in the file-based workflow.

Much better to perform QC automatically, not in real time but as resources are available. A comprehensive set of checks, from video and audio levels to photo- sensitive epilepsy compliance, can be performed on content considerably faster than real time on a modern Windows PC running the Hamlet Reel- Check software. Only when issues are found need an operator become involved, and a QC pass can be reported automatically to the asset management system to release the content for playout. The most recent edition is Reel-Check Enterprise which allows multiple instances of quality control tests on video/audio media content to run in parallel across multiple servers, workstations or blades, increasing throughput of common task schedules. Windows PC based without needing specialist hardware.

Today’s broadcast engineers continue to face technical and operational challenges. Test and measurement suppliers like Hamlet continue to innovate to meet them. Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48
Produced with Yudu - www.yudu.com