<div dir="ltr"><div class="gmail_extra">Sadly Tony, SDR won't help, it's about the laws of physics.<br><br></div><div class="gmail_extra">To make an efficient antenna you typically need one quarter of a wavelength. For FM/VHF thats about 75 cm - faily easy with a bit of copper pipe or suchlike. For medium wave a quarter wave can be as much as 139m - that's 456ft - meaning serius steelwork and/or guy wires that take a large area of ground.. Moreover at lower fequencies the "ground plane" becomes more important - which often means burying loads of copper in the ground to increase its conductivuity.<br><br></div><div class="gmail_extra">So a 400ft mast plus digging up an acre or two of ground gets quite expensive! Or build a less effecient antenna, but put-up with having to use a bigger transmitter and possibly having reduced audio bandwidth/quality. Or put your transmitter on a boat in the north sea - a technically perfect location for a AM transmitter, but the Offshore Radio Act tends to suggest you shouldn't do it, et alon the tendering costs!<br><br></div><div class="gmail_extra">And all that to provide a 20th century transmission arrangement that's days are numbered. Finacial suicide!<br><br></div><div class="gmail_extra">Glyn<br></div><div class="gmail_extra"><br>-- <br>Glyn Roylance - Principal Consultant
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<div><a href="http://www.a-bc.co.uk/" target="_blank">Associated Broadcast Consultants</a></div></div><br></div><div class="gmail_extra"><br><br><div class="gmail_quote">On 14 September 2015 at 19:53, Tony Bailey <span dir="ltr"><<a href="mailto:ravensound@pilgrimsound.co.uk" target="_blank">ravensound@pilgrimsound.co.uk</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<div>Reading this thread may explain why
none of the last London tranche AM licensees (new not existing)
got on the air. There are a number of LRSLs around the country on
AM although of course they only have to radiate 1 Watt. Maybe
it's a job for the SDR black box brigade to take on now that
they've finished playing with DAB? DRM anyone?<br>
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Regards, Tony Bailey<br>
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