Good stuff.


True, but Clarkstown the same as pretty much all high power LW installations since the mid 80s doesn't broadcast AM, it broadcasts PulsAM. The resulting spectrum consists of the carrier, a central region of roughly +/-1kHz corresponding to the foot and summit of the carrier slew, and complex harmonics that are a function of the carrier slew rate and duty cycle, where the 'amplitude' of the audio input corresponds to the instantaneous duty cycle. Have a look at the spectrum up close in the Peterborough SDR waterfall (use the 'Zoom In' button), it's quite mesmerising.

This morning when I took a quick look at 252 to check the SDR was up and running, there was a piece of flute music which generated a beautiful pattern of switching transients. Provided you notch out roughly +/-2 kHz then these transients can only beat with each other to produce stray audio. Even for a pure tone these are only a functional of the duty cycle, switching frequency, input audio frequency and input audio amplitude, so will just sound like anharmonic noise.

Fair enough, until someone rocks up on this thread who can clarify whether it's an LC shunt or more complex LP filter that's in use, no-one can say for certain, and I'm not sure anyone monitoring this thread is very much interested either. Deck chairs, Titanic, etc....

RTE on 252 broadcast in AM.
Pulse AM is something different.

You really know nothing.

Would you care to expand. Rather than just post your usual vague notions, inaccuracies and useless rubbish.

Looking at the soec of the 2007 Transradio 252 transmitter it does have PDM Pulse Duration Modulation which is equivalent to PWM Pulse Width Modulation or PulseAM which makes the AM transmitter more effecient.
But with the low listening to 252 still a high cost per user and RTE is still saying it will be switched off in 2017 with existing users moved to digital (online and satellite).
The 10 year old transmitter could be sold and work on MW, India might be a buyer if it is still capable of DRM. But with decomissioning, transport and reinstall is it worth it?.

My notions are not vague.
It is AM. That is it.
What you see in the waterfall of 252 is exactly the same as what you will see in the waterfall of a "conventionlly" modulated AM ttansmitter.

The only inaccuracies are in your posts.

Yes, the transmitter uses PDM to generate the modulation.
Pulse AM is different.

I thought that the DRM modulator was a retrofit and had been flogged off since? Would be interesting if it were still kicking around at Clarkstown.

It wasnt a retrofit. The tx was designed for DRM and It wasn't "flogged off", it was returned.

Any update on the "consultative steering group" that RTE are working with ? The campagain to save 252, move to 261 etc seems to have gotten very quiet recently

Is there actually any campaign to move to 261, outside of this and maybe a few other bulletin boards?

Simple answer, no.

The official save lw campaign has mentioned it a few times http://savertelongwaveradio.com/the-...t-be-extended/

RTE's 252LW due to have an outage for several hours from around 10AM this Wednesday:
according to http://www.rte.ie/aertel//desktopxhtml/169-2.html

Maintenance? On something due to close? Or does this confirm the reprieve?

It's better to listen to it on DVB, DAB, TuneIn, Irish Radio Player and FM than on the old lady of LW.

Time to shutdown both Radio 4 LW and RTE LW and so end broadcasting on the platform in both the UK and Ireland.

23rd November. Now that date rings a bell

Why does Divid16 want to kill off long wave broadcasting? What is it to him how other people listen to radio?

Some newer radios in the last few years don't seem to have LW band anymore. The just have FM/AM(MW) or in some cases just FM/DAB.
I still got an old portable battery radio that I got in the late 90s that I hardly ever use anymore and that has FM/AM(MW)/LW and Two short Wave bands.

Darren

Yes, not many portables seem to have LW. Strangely most car DAB radios also seem to have LW (and FM/MW).

Probably because it costs a small fortune to keep the transmitters on, large antenna systems which require an equally large site area, etc., etc., and really not that many people listening to LW since any LW opt-outs of BBC R4 on LW are carried on DAB> as a secondary service.

Not correct: the noon shipping forecast is LW only, and Yesterday in Parliament is often LW only when there aren't enough bits available, e.g. during pop-ups.

Like 252 closing in 2017, (the maintenance will keep the site going untill 252 listeners go to internet or satelite and the outage will give a chance to see who complains about the break), notice on 198 was given in 2011 that it will close in about 10 years or if the transmitter is too expensive to repair
http://www.radiotimes.com/news/2011-...ion-must-mourn

Most likely when the electric switching contract ends iin 2021 and more boats get Navtext and satellite warning systems.

The shipping forecast isn't just for large boats ---- it's also for dinghy sailors,pleasure craft ,inshore fishermen and anyone who lives on the coast (and inland) --- in other words anyone who needs an up to date forecast and isn't near the internet,mobile phone coverage or in range of a Coastguard station to get the every 3 hours forecast.
I'm lucky --- I have a hand held VHF radio and a local Coastguard mast ..
Regards

I would not have it would be impossible to put the noon shipping forecast on DAB as a secondary service. But why is the shipping forecast necessary, hardly anyone uses it. The MCA put out forecasts on VHF all day, most vessels have electronic systems to get the forecasts and gale warnings.