The SCTE Eurolecture Meeting, 2002.

The Society held its second mainland Europe lecture meeting on 26th June. The Society's European Lecture Meeting was held at Veenendaal in The Netherlands, at the headquarters of Patron Member, Tratec BV. Five papers were presented and whilst all had a digital flavour, they were diverse and diverting! The attendees were treated to expert expositions of Broadband engineering topics.

	The meeting was lively with the usual superior mix of SCTE Lecture Meeting discussion points. The day was opened by Jos Huizer, CEO of Tratec, who set the theme of the day by demonstrating that the industry had undergone subtle changes, not deep-seated revolution, and these were really only apparent when one viewed them retrospectively.

The next speaker was Dr Roger Blakeway, SCTE President, who introduced the SCTE to non-members, outlining the nature of the Society and stressing that it was about engineers and not companies. The SCTE was the very original Society, founded in 1945. He went on to enumerate the Society's activities, its part in IBC, and the relationship it has to bodies involved with setting high technical standards. These introductions were followed by the technical papers summarised below.

	"Planning the Cable Network for Future Digital Loading" was the subject tackled by Matti Susi, Systems Consulting Manager at Teleste Broadband Cable Networks. He began by presenting an analysis of the amplitude properties of DVB-C using QAM and analogue PAL signals, then proceeded to discuss the effects of digital channel loading right up to the final and intriguing supposition that there would be digital channels only on the HFC network. The placing of narrowcast channels in the DWDM spectrum also raised some interesting points and showed that such channels should be grouped together to avoid the effects of non-linear distortion. The ouput levels of network RF amplifiers would need to be controlled accurately, the overload characteristics of push-pull, power-doubling and Gallium Arsenide amplifiers were revealing. Of the three, the GaAs amplifier had the best output capability but also the most rapid onset of second and third order distortion. Although all the talk nowadays is of Fibre to the Home, the continued employment of HFC networks for digital signals would pose few problems.

"The Set-Top Box as a Home Gateway" was presented by Kuldip Johal of Pace Micro Technology PLC. The role of the Set-Top Box as a Home Gateway is seen by Pace as the next step in extending the cable network beyond the cable termination unit into the home network. The actual connection to the home network will probably be established by a wiress link to computers and telephones, but retain a broadband cable connection to the television receiver. This concept is being tested currently by Telewest and NTL. The design criteria are that it must be customer installed, secure, and monitored and controlled by the network operator. The Home Gateway would provide Internet Radio, an 'always-on' data connection for the Internet, and permit a level of home automation. Supervision of home appliances, smoke and Carbon Monoxide detectors and utility meters is included. Further features include a home video recording function, selective advertising, VoD, a better level of inter-active operation and programme storage. Probable future applications would include Games and Music storage and a home information cache.>

	"EuroDOCSIS 1.0 & 1.1 Cable Modem Technology and its Certification" presented by Wim De Ketelaere of tComLabs. He began with the manner in which the specification we know as EuroDOCSIS evolved, and discussed the certification process and the provision of six training courses each of two days in length. EuroDOCSIS is an annexe to the main DOCSIS specification and was co-ordinated at Ghent University in February 2000. In May of 2000 tComLabs was founded, again in Ghent, to perform the testing. The certification Board was created at the same time to grant certification to devices passing the test procedures. tComLabs are responsible for the development of testing procedures, any discussions on the certification, and for performing the tests. It also handles any feedback to equipment vendors and organises training sessions for their engineers. The first certificates were granted in June of 2000 by the Certification Board. Mr De Ketelaere also discussed the DOCSIS 1.0 and 1.1 specifications with particular emphasis on the EuroDOCSIS derivative.

"Digital Measurements, What Have we Learned?" Chris Swires, SCTE Vice-President and Managing Director of Swires Research Ltd gave a very amusing talk about the experiences of his company over the four years of practical experience with measuring digital signals. The measurement of bit error ratio takes a long time, and a more meaningful and rapid assessment of signal quality can be derived from Modulation Error Ratio, that can also indicate signal-to-noise ratios. Caution in measuring sig/noise ratio should be taken, the noise must be measured close to the signal frequency or in a quiet spot and compensation added for the sloped gain/frequency characteristic of the network. An interesting yet entertaining lecture in the Swires tradition.

	"Intermodulation Caused by Ferrite Components in Passives" Keith Mothersdale, Director of International Business Development at Tratec BV, gave a very practical demonstration of intermodulation caused by ferrite components in passives on the network. High signal levels from cable modems can cause ferrite cores to saturate, and this is particularly so when the ferrite has become magnetised. Simple de-gaussing of the ferrite provides immediate relief, but the problem will return over time as the cores remagnetise. In the picture, a colour bar test pattern signal and a high level signal from a generator are passed through a passive splitter containing ferrite-cored components. The effect with a ferrite components that have not been de-gaussed is marked, and the application of a de-gaussing wand identical to those used for many years to de-gauss shadow-mask colour TV CRTs was shown to clear the intermodulation produced in a very graphic way.

The Society believes it has much to offer to cable telecommunications engineers in continental Europe and the success of this latest meeting seems to confirm this. If you are a patron member with premises in continental Europe and would be willing to host a similar meeting in the future, please email the SCTE office


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