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<body class='hmmessage'><div dir='ltr'>Not so I'm afraid Phil.<div>The information that we have suggests that <span style="font-size: 12pt;">transmitters for the project will be produced specifically by a UK manufacturer already producing similar equipment for existing broadcasters.</span></div><div><span style="font-size: 12pt;">Ian</span></div><div><span style="font-size: 12pt;"><br></span></div><div><span style="font-size: 12pt;">------------------------------------------------</span></div><div><div><br><div>> Date: Sun, 8 Mar 2015 18:36:25 +0000<br>> From: office@fantasyradio.co.uk<br>> To: cma-l@mailman.commedia.org.uk<br>> Subject: [cma-l] DAB trials<br>> <br>> Whilst we're delving deeply into the theory of RF propogation, I suggest <br>> there could be another reason for Ofcom's suggesting 100 watts. Clearly, <br>> to acheive 10km radius at 220MHz, you'll need more power than 5km at <br>> 100MHz. So, perhaps Ofcom have 'sourced' a handful of 100 watt models, <br>> which will be OK for this trial, which is all guesswork anyway.... It <br>> has to be, as there are so many unknown quantities.<br>> <br>> Most importantly, whatever comes of this trial, it'll be an awful lot of <br>> work for a handful of people. The most important consideration must be <br>> 'how does this affect the listener?' and how will it benefit our <br>> station? Probably the most overlooked questions in all of this debate.<br>> <br>> <br>> Phil Dawson<br>> FANTASY RADIO 97FM<br>> Devizes ,<br>> Wiltshire<br>> <br>> <br>> On 08/03/2015 16:21, cma-l-request@mailman.commedia.org.uk wrote:<br>> > Send cma-l mailing list submissions to<br>> > cma-l@mailman.commedia.org.uk<br>> ><br>> > To subscribe or unsubscribe via the World Wide Web, visit<br>> > http://mailman.commedia.org.uk/mailman/listinfo/cma-l<br>> > or, via email, send a message with subject or body 'help' to<br>> > cma-l-request@mailman.commedia.org.uk<br>> ><br>> > You can reach the person managing the list at<br>> > cma-l-owner@mailman.commedia.org.uk<br>> ><br>> > When replying, please edit your Subject line so it is more specific<br>> > than "Re: Contents of cma-l digest..."<br>> ><br>> ><br>> > Today's Topics:<br>> ><br>> > 1. Re: Ofcom announces trials to help small stations join<br>> > digitalradio - 100w limit (Tony Bailey)<br>> ><br>> ><br>> > ----------------------------------------------------------------------<br>> ><br>> > Message: 1<br>> > Date: Sun, 08 Mar 2015 15:58:21 +0000<br>> > From: Tony Bailey <ravensound@pilgrimsound.co.uk><br>> > To: cma-l@mailman.commedia.org.uk<br>> > Subject: Re: [cma-l] Ofcom announces trials to help small stations<br>> > join digitalradio - 100w limit<br>> > Message-ID: <54FC719D.6080100@pilgrimsound.co.uk><br>> > Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"<br>> ><br>> > Ofcom states that the coverage limit is set at 40% of the "corresponding<br>> > local DAB multiplex area" and that a practical limit of 100 W ERP "may<br>> > achieve a service area of approximately 10 km radius". A synchronised<br>> > two tx (not repeater) system would be spaced at no more than 15 km<br>> > apart. As pointed out below, this has to based on a practical antenna<br>> > situation to have any relevance.<br>> ><br>> > Tony Bailey<br>> ><br>> > On 08/03/15 14:01, Ian Hickling wrote:<br>> >> It seem there's a lot of second-guessing going on here from people who<br>> >> may know a lot about administration and encoding but possibly not so<br>> >> about the black magic that is RF propagation.<br>> >> There's no point in trying to relate 100W ERP to 5km for Band III DAB<br>> >> - just as it's equally irrelevant to relate 25W with FM to 5km - sorry.<br>> >> Topography, geology, refraction, refraction, foliation, antenna<br>> >> efficiency and launch conditions have far too large an influence.<br>> >> In terms of propagated signal transit, there's not a huge difference<br>> >> in practical terms between FM at say 100 MHz and DAB at 200 MHz when<br>> >> you take into account antenna size, efficiency, reflection and refraction.<br>> >> Because of the difference between demodulation formats, a receiver<br>> >> can tolerate a much lower signal level on DAB than on FM to resolve an<br>> >> acceptable audio service.<br>> >> This was originally proposed at 20dB from the point of view of<br>> >> transmitted power but then revised to 10dB - meaning that a DAB<br>> >> transmitter in Band III would need one tenth of the ERP of an FM<br>> >> transmitter in Band II to achieve the same audience.<br>> >> Hence it is puzzling why Ofcom has set so high a required signal level<br>> >> for a DAB service area of the order of 72dBuV/m as opposed to 54<br>> >> dBuV/m for FM.<br>> >> Beware - there is a distinct difference between a Power Decibel in<br>> >> transmission and a Voltage Decibel in reception!<br>> >><br>> >> Let's not invoke DAB+ and DRM - Ofcom specifically rules them out in<br>> >> 2.30 and 2.32<br>> >><br>> >> Yes, Block 5A would be ideal as it's relatively clear, allocated and<br>> >> accessible to modern receivers - but Ofcom apparently doesn't accept<br>> >> that as it hasn't headed straight for it.<br>> >><br>> >> As I've protested many times, there is technically nothing at all to<br>> >> prevent a standalone transmitter radiating a single programme stream<br>> >> to serve a discrete area either on DAB, DAB+ or DRM as far as I'm<br>> >> aware. If I'm wrong I'd appreciate the exact reasons why.<br>> >><br>> >> Looking at only the RF component in the transmission chain, several UK<br>> >> manufacturers could offer a 2U Band III 300W unit at around ?2000 if<br>> >> the demand were high enough - no real cost differences from today's<br>> >> Band II units.<br>> >><br>> >> Let's not get distracted - the encoding is software-defined - the<br>> >> actual RF transmitter is not!<br>> >><br>> >> Ian<br>> >><br>> >> ------------------------------------------------------------------------<br>> >> Date: Sun, 8 Mar 2015 11:13:25 +0000<br>> >> Subject: Re: [cma-l] Ofcom announces trials to help small stations<br>> >> join digitalradio - 100w limit<br>> >> From: alan.coote@5digital.co.uk<br>> >> To: tlr@gairloch.co.uk; transplanfm@hotmail.com; info@a-bc.co.uk<br>> >> CC: cma-l@mailman.commedia.org.uk<br>> >><br>> >> I can't help thinking that someone at Ofcom ran the simulations and<br>> >> came up with 100W = 5km radius.<br>> >><br>> >> Therefore if small scale DAB became a reality it wouldn't annoy Radio<br>> >> Centre too much (they'd still complain as that's their mentality) and<br>> >> at worst secondary legislation could make it happen.<br>> >><br>> >> Kind Regards<br>> >><br>> >> Alan<br>> >><br>> >><br>> >> Hear Alan Every Week on Let's Talk Business The UK's Premier Radio<br>> >> Programme For Current and Future Entrepreneurs - Now Broadcast To Over<br>> >> 5 Million People <http://www.letstalkbusinessonline.com/><br>> >><br>> >><br>> >> From: "tlr@gairloch.co.uk <mailto:tlr@gairloch.co.uk>"<br>> >> <tlr@gairloch.co.uk <mailto:tlr@gairloch.co.uk>><br>> >> Reply-To: "tlr@gairloch.co.uk <mailto:tlr@gairloch.co.uk>"<br>> >> <tlr@gairloch.co.uk <mailto:tlr@gairloch.co.uk>><br>> >> Date: Sunday, 8 March 2015 00:45<br>> >> To: "transplanfm@hotmail.com <mailto:transplanfm@hotmail.com>"<br>> >> <transplanfm@hotmail.com <mailto:transplanfm@hotmail.com>>, Associated<br>> >> Consultants <info@a-bc.co.uk <mailto:info@a-bc.co.uk>><br>> >> Cc: "cma-l@mailman.commedia.org.uk<br>> >> <mailto:cma-l@mailman.commedia.org.uk>" <cma-l@mailman.commedia.org.uk<br>> >> <mailto:cma-l@mailman.commedia.org.uk>><br>> >> Subject: Re: [cma-l] Ofcom announces trials to help small stations<br>> >> join digitalradio - 100w limit<br>> >><br>> >> I simplistically presumed they settled on the 100W suggested limit on<br>> >> the basis that at the Band III frequencies of DAB it would give<br>> >> roughly the same coverage area (at 58dBuV/99%) as 25W on Band II (at<br>> >> 54dBuV/90%).<br>> >> NB the average *local* DAB multiplex power is 1.3kW, not 2kW, but of<br>> >> course they tend to be from sites with much higher antennas than<br>> >> economically available to community stations, so the chances are the<br>> >> 100W represents an even tinier coverage area in comparison to current<br>> >> local multiplexes than might appear at first sight from a simple<br>> >> comparison of powers. But I can see it is much easier for Ofcom to<br>> >> control the allowed power than to get into arguments over exact<br>> >> percentages of area covered. Maybe 500W would have been more realistic<br>> >> if they wanted to take that simplistic approach, with a lower limit<br>> >> applied in the few cases where 500W coud cause difficulties.<br>> >> (I guess there is also the question that Ofcom is paying for the<br>> >> transmitters in the trial, and a band III amplifier running at , say,<br>> >> 250W is a lot more expensive than a 50W one, especially if one uses<br>> >> the technique of greatly underrunning a much higher power design to<br>> >> help achieve the necessary linearity.).<br>> >> Seems to me that block 5A, (currently unused, but allocated for local<br>> >> DAB) could be used as a UK-wide frequency block for terrain limited<br>> >> single station services up to 500W to deal with all the areas where<br>> >> there is a low density of local stations (ie only one within the<br>> >> interference range of a 500W TX) and it could be done tomorrow,<br>> >> without any fancy trials or risk of interference, clearing out one<br>> >> whole tier of demand without any fuss, leaving trials and more<br>> >> complicated sharing and co-channel planning issues to be threshed out<br>> >> over time in the other seven frequency blocks allocated to local<br>> >> ensembles in areas of more dense demand. It's also much lower in<br>> >> frequency than the other blocks, which reduces the demands on the<br>> >> low-cost software defined transmitter.<br>> >> Alex<br>> >><br>> >> On 25 February 2015 at 13:04 Associated Broadcast Consultants<br>> >> <info@a-bc.co.uk <mailto:info@a-bc.co.uk>> wrote:<br>> >><br>> >> We challenged the 100w limit in the consultation - suggesting that<br>> >> the "no greater than 40% of the local commercial Mux area" was an<br>> >> adequate limit. 100w is roughly 5% of the average existing DAB<br>> >> transmitter power, so presuming community stations don't deploy<br>> >> their DAB transmitters using tethered balloons or satellites etc<br>> >> they unlikely ever to get near 40% unless they deploy multiple<br>> >> numbers of transmitters (thus undermining the low-cost aim).<br>> >> The standard consultation deflection response was invoked (ie:<br>> >> address a different question) - stating that "it is not<br>> >> necessarily the case that allowing a higher power will in all<br>> >> cases reduce the number of transmitters needed". We never said it<br>> >> would in all cases, but were suggesting that by removing the 100w<br>> >> cap you retain some flexibility when it /would/ make a difference<br>> >> in some cases! Unfortunately though, consultations are single shot<br>> >> - no possibility to clarify the point or challenge the response.<br>> >> I think we can all imagine the real (unstated) reason why they are<br>> >> limiting it to 100 watts ;-)<br>> >> Don't get me wrong - 100w at 200MHz can still provide useful<br>> >> coverage if planned correctly (other DAB coverage planning<br>> >> services are available!), but in some cases more may be required.<br>> >> Otherwise we risk repeating the same problem that analogue CR has<br>> >> - the paltry standard 25w power is often inadequate and quite<br>> >> literally blasted off the dial by much stronger commercial and BBC<br>> >> signals. And this problem is even worse with DAB (for technical<br>> >> reasons that I will not go into here).<br>> >> Glyn<br>> >> --<br>> >> Glyn Roylance - Principal Consultant<br>> >> Associated Broadcast Consultants <http://www.a-bc.co.uk/><br>> >> _______________________________________________<br>> >><br>> >> Reply - cma-l@commedia.org.uk <mailto:cma-l@commedia.org.uk><br>> >><br>> >> The cma-l mailing list is a members' service provided by the<br>> >> Community Media Association - http://www.commedia.org.uk<br>> >> Twitter: http://twitter.com/community_media<br>> >> http://www.facebook.com/CommunityMediaAssociation<br>> >> Canstream Internet Radio & Video: http://www.canstream.co.uk/<br>> >> _______________________________________________<br>> >><br>> >> Mailing list guidelines:<br>> >> http://www.commedia.org.uk/about/cma-email-lists/email-list-guidelines/<br>> >><br>> >> _______________________________________________<br>> >><br>> >> To unsubscribe or manage your CMA-L mailing list subscription<br>> >> please visit:<br>> >> http://mailman.commedia.org.uk/mailman/listinfo/cma-l<br>> >><br>> >><br>> >> _______________________________________________ Reply -<br>> >> cma-l@commedia.org.uk <mailto:cma-l@commedia.org.uk> The cma-l mailing<br>> >> list is a members' service provided by the Community Media Association<br>> >> - http://www.commedia.org.uk Twitter:<br>> >> http://twitter.com/community_media<br>> >> http://www.facebook.com/CommunityMediaAssociation Canstream Internet<br>> >> Radio & Video: http://www.canstream.co.uk/<br>> >> _______________________________________________ Mailing list<br>> >> guidelines:<br>> >> http://www.commedia.org.uk/about/cma-email-lists/email-list-guidelines/ _______________________________________________<br>> >> To unsubscribe or manage your CMA-L mailing list subscription please<br>> >> visit: http://mailman.commedia.org.uk/mailman/listinfo/cma-l<br>> >><br>> >><br>> >> _______________________________________________<br>> >><br>> >> Reply - cma-l@commedia.org.uk<br>> >><br>> >> The cma-l mailing list is a members' service provided by the Community Media Association - http://www.commedia.org.uk<br>> >> Twitter: http://twitter.com/community_media<br>> >> http://www.facebook.com/CommunityMediaAssociation<br>> >> Canstream Internet Radio & Video: http://www.canstream.co.uk/<br>> >> _______________________________________________<br>> >><br>> >> Mailing list guidelines: http://www.commedia.org.uk/about/cma-email-lists/email-list-guidelines/<br>> >> _______________________________________________<br>> >><br>> >> To unsubscribe or manage your CMA-L mailing list subscription please visit:<br>> >> http://mailman.commedia.org.uk/mailman/listinfo/cma-l<br>> ><br>> <br>> _______________________________________________<br>> <br>> Reply - cma-l@commedia.org.uk<br>> <br>> The cma-l mailing list is a members' service provided by the Community Media Association - http://www.commedia.org.uk<br>> Twitter: http://twitter.com/community_media<br>> http://www.facebook.com/CommunityMediaAssociation<br>> Canstream Internet Radio & Video: http://www.canstream.co.uk/<br>> _______________________________________________<br>> <br>> Mailing list guidelines: http://www.commedia.org.uk/about/cma-email-lists/email-list-guidelines/<br>> _______________________________________________<br>> <br>> To unsubscribe or manage your CMA-L mailing list subscription please visit:<br>> http://mailman.commedia.org.uk/mailman/listinfo/cma-l<br></div></div></div> </div></body>
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