Originally Posted by hanssolo:
“...Wonder had the analogue signal remained on 567, and 252 could have became DRM full time (rather than just overnight) with help from commercial groups. Also Roberts (as a leading radio set brand, rather than Morphy Richards) released their DRM prototype set in High Street shops with the help of Radio Luxemburg and religous stations on SW, DRM might have taken off in UK and Ireland? But sadly was not to be....”
Even if DRM30 receivers had become widely available, one of the findings of the
Project Mayflower Trial was that fully to unlock the performance improvement possible with DRM30, it would be necessary to re-plan MW networks around a larger number of lower power TXs, so that field strengths never fall below the digital cliff threshold. The Beeb also suggested relaxation of the AM-DRM backoff for stations wishing to convert, although this is less of a show-stopper particularly as AM and DRM mean powers are already dissimilar due to COFDM's crest factor.
After the Plymouth trial DRM30 was effectively dead, as the Bright Young Things at the Beeb were already down on the "ancient modulation" network, never mind being asked to cough for roughly three times the number of site locations for an SFN. Had there been sets available though, DRM from Clarkstown would have been a winner due to the much greater night-time coverage area alone, never might any of the other quality benefits.
Originally Posted by Ex Pat:
“BIB. Inductors and coils are the same things. The ATU, or matching unit, is to match the base impedance of the antenna to the transmitter/feedline. It doesn't actually tune the aerial.”
<scratches head>Still recovering from the traditional Friday evening shenanigans here, but isn't that the same thing? What does BIB mean?
Third year 'Electrical Machines' lectures at Glasgow Uni are now quite hazy in Vectorsum's bonce, but I thought that inductors 'induced', i.e. you needed either a self-tap or a coupled/coaxial counterpart inductor to have current 'induced' in it by the lines of magnetic flux. Coils simply act in-line to present an inductive impedance, i.e. voltage preceding current by 90 degrees.
Having said that, I can only think of one true instance of a coil around an AM site, the coil that usually forms part of the earth side of the lightning flashover assembly.
Originally Posted by Ex Pat:
“Most if not all phoneline RFI filters I have seen are bandpass, not notch. They usually come in different ranges. e.g. 500 KHz to 1.5 MHz.
Chances are that the filters used there are good for the whole LW band. Incidentally, I've used the ASDL filters with reasonable good success for eliminating RFI on my phone.”
I think you mean band-stop instead of bandpass? Sure you can use band-stop filters as well, but you need twice the number of components as each side of the incoming two wires needs a filter due to poor common-mode rejection in the phone plus attachment cord. An RF notch filter, OTOH, is just an L and a C in series, shunting the line as close to the phone as practical. A disclaimer being that, same as everyone else posting here, I've no idea what RTÉ has dished out to the punters around Summerhill.