[opendtv] Re: First look at ATSC HD Broadcast
- From: "John Willkie" <JohnWillkie@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Sat, 11 Jun 2005 21:57:06 -0700
I challenge you on the assertion that the test was being conducted by FCC
engineers. It was conducted by engineers for MSTV and the NAB.
If you meant engineers who practice before the FCC, you could/should have
said that.
Us engineers tend to speak more precisely than you. When somebody is our
partner on Friday, they remain our partner on Saturday.
John Willkie
----- Original Message -----
From: "Bob Miller" <bob@xxxxxxxxxx>
To: <opendtv@xxxxxxxxxxxxx>
Sent: Saturday, June 11, 2005 7:12 PM
Subject: [opendtv] Re: First look at ATSC HD Broadcast
> Let the full story be told. Before the test began I offered a Victor
> Tawil our help in supplying or procuring 6 MHz COFDM receivers. He
> informed me that they had all they needed. I offered to participate with
> and to help in anyway since we had been testing COFDM receivers and had
> trapsed all over Europe talking to those making receivers. He didn't
> need any help.
>
> They had carefully found an obscure British company who didn't have a
> clue as to what was going on and disregarded written instructions on
> using a front end filter. They didn't say anything to this company about
> what they were testing.
>
> This test was being conducted by top US engineers from the FCC why would
> they not know what to ask for? How to ask for it?
>
> I give them the benefit of the doubt. I think they were profesional
> engineers well educated in RF technology and I think they knew EXACTLY
> what to ask for and from whom to ask it.
>
> Here is what BT had to say about the request that was copied to Victor
> Tawil.
>
> Bob Miller
>
> BROADCAST TECHNOLOGY LTD
> Sopwith Park
> Royce Close
> West Portway Industrial Estate
> Andover
> Hampshire
> SP10 3TS
> United Kingdom
> Tel: +44 (0)1264 332633
> Fax: +44 (0)1264 334509
> E-mail: btech@xxxxxxxxxxxxxx
> Website: http://www.btl.uk.com
> Registered Number 2143040
> Registered Office: 26a High St, Andover, Hampshire, SP10 1NN
> Date: 22/1/2002
> Ref: NJ/IK
> Lynn Caudle
> Senior Vice President, Science & Technology
> National Association of Broadcasters
> 1771 N Street,
> Washington
> DC 20036
> United States of America.
>
> Dear Mr. Caudle,
> As Managing Director of Broadcast Technology Limited, I would like to
> make a statement of fact regarding the Broadcast Technology Ltd (BTL)
> DVTM2000(T) Digital Terrestrial Transmitter Monitors used in the
> recently concluded “Phase I” comparative testing of the MSTV/NAB -
> VSB/COFDM Project. It has come to my attention that my company’s product
> is being blamed for providing less than optimal performance. The fact is
> that our product was used in a manner for which it was not designed nor
> intended, and the result of this misguided use has lead to misleading
> results and incorrect conclusions. In a single sentence, the integrity
> and validity of the data collected using our products in an un-protected
> terrestrial receiving environment inconsistent with its intended use can
> be dismissed as being irrelevant at best.
>
> The DVTM2000(T) product line, as indicated by the product title, is a
> series of professional products offered for the monitoring of DVB-T
> COFDM transmitter performance and emissions. Part of this monitoring
> includes the ability to accurately record and reproduce the frequency
> response spectrum of a transmitter. Monitoring receivers must in no way
> impair or “colour” this response. It is for this reason that our
> monitoring grade units have wideband input. General reception receivers,
> on the other hand, need to have frequency selective inputs in order to
> reject any high level “off
> channel” signals. However, to achieve this selectivity, tracking filters
> that work over a range from 55MHz up to 850MHz have to be used. These
> filters introduce distortions that can cause rounding or tilt of the
> received signal.
>
> The DTVM(T) was not designed nor intended to operate in the harsh and
> open world of an out-of-doors terrestrial receiving environment. Such
> operation is possible, but possible only by taking prudent steps such as
> providing proper channel pre-selection filtering, and maintaining proper
> signal levels at the equipment inputs. For the purposes of field trials
> or monitoring, as opposed to transmitter measurement, a new version of
> the DTVM 2000, with selective input has been under development. This
> unit would have been infinitely more suitable for the trials that have
> recently been undertaken.
>
> When in mid 2000, BTL was contacted by US organisations requesting it to
> provide equipment that would be used in conjunction with a series of
> comparative tests of DVB-T’s COFDM and the US ATSC 8VSB technologies, we
> proudly responded to this request by providing five (5) of our
> transmitter monitors for testing purposes. The nature of such testing
> requires an understanding of many separate engineering
> disciplines and techniques, and implies that measures to insure proper
> operation are being provided for equipment applications by qualified
> personnel. These steps were not taken.
>
> 2.
> It is hardly surprising to me and my engineers, now fully understanding
> the nature of the testing performed, that erroneous results were
> obtained regarding DVB-T COFDM reception capabilities in multiple
> locations using our transmitter monitoring equipment. It is our combined
> professional opinion that the results obtained while operating our
> professional product in the environment now stated as being a direct
> antenna connected environment with various FM, Low VHF & High VHF,
> multiple high power UHF, land-mobile and cellular communications
> existing, are totally without merit. Had we been made fully aware of the
> nature of the testing at the time of the original request for equipment,
> and the RF
> environment our equipment was to be operated in, we would have made
> specific recommendations to include channel pre-filtering or acquire
> other equipment more appropriate to the needs.
>
> As a respected provider of quality professional equipment to the
> Broadcast industry, we stand by our products and the performance
> provided when operated in a manner consistent with the products design
> parameters. The particular product chosen for this important comparative
> test, the DVTM2000(T) Digital Terrestrial Transmitter Monitor, was not
> designed to operate under the difficult and challenging conditions
> which were chosen. Under these circumstances we would have recommended
> an alternative version. Data collected without proper pre-selective
> filtering will be subject to failure in many of the environments we
> understand to exist. Tabulation of results will indicate failures due to
> inappropriate operation, not failures of the transmission system. Once
> again, the integrity and validity of the data collected using our product
in
> a direct antenna connected terrestrial receiving environment can be
> dismissed as being irrelevant and speculative at best.
> We hope that the above will clarify the situation and would be pleased
> to answer any questions that might arise.
>
> Yours sincerely,
> Nicholas Jennings
> Managing Director
> Broadcast Technology Ltd
>
> Copy to: Victor Tawill Sen.VP MSTV.
>
> John Golitsis wrote:
>
> >And just so the full story is re-told, that "receiver" was offered by the
> >manufacturer as one that would fit the needs of the testing. We all read
> >the official request, and the official reply, and the manufacturer failed
to
> >make any mention at all of it's need for front end filtering. Nor did
> >Sinclair who was in possession of the receiver before it was passed on to
> >the NAB.
> >
> >Of course, AFTER the testing was completed is when this all came up. How
> >bloody convenient.
> >
> >----- Original Message -----
> >From: "Dale Kelly" <dalekelly@xxxxxxxxxxx>
> >To: <opendtv@xxxxxxxxxxxxx>
> >Sent: Saturday, June 11, 2005 1:37 PM
> >Subject: [opendtv] Re: First look at ATSC HD Broadcast
> >
>
>
>
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