BBC WS & RTL using AMSS (AM signaling)

[simone]

Hi all,
here is an example of one of the BBC WS analogue MF transmissions using AMSS to broadcast some data, besides the station label there is also information for receivers (like AF lists) referring to the DRM broadcasts.
Simone
PS: Thanks to the BBC for making the sources available!

[simone]

9410 kHz

and here the same data received on HF
Simone

[dk8cb]

And here is a screenshot of the improved version with a bigger AFS (alternative frequency service) window that now allows one to see everything without one having to use the slider.

Very nice!

Roland

[carknue]

Who else uses AMSS? Just BBC?

[simone]

Hi Carsten,
as far as I know, at the moment only BBC WS are using AMSS on their AM transmissions on 648 kHz and 9410 kHz (see AF´s in the attachments above), hopefully there will be some others in the future!
Simone

[dk8cb]

What AMSS is

For an explanation on what AMSS is all about and how it works, have a look at this explanation given by James Briggs.

Roland

[jbriggs]

Try Beidweiler (234 kHz) !?

[carknue]

Originally posted by jbriggs
Try Beidweiler (234 kHz) !?

Yeah, here it is.

[dk8cb]

Originally posted by jbriggs
Try Beidweiler (234 kHz) !?

Vraiment !

A bit different on the new AMSS window in today's CVS release, see screenshot.

Roland

[simone]

Hi all,
strong signal from Beidweiler (thanks James for the frequency information), no problem decoding the AMSS, but that´s what it looked like after tuning in again on a BBC frequency
Btw is there a problem with signalling or are all the stations really not using any type of carrier control?
Simone

[jbriggs]

Btw is there a problem with signalling or are all the stations really not using any type of carrier control?

I think that 648 kHz does use carrier control, either AMC or DAM. I think 9410 kHz does not use carrier control, but I am not totally sure. I can check.

Just a bit of info for those not familiar with Dynamic Carrier Control (DCC) & also the reason this is signalled:
With a normal AM transmission the power in the central carrier is always fixed. There are different types of DCC, but essentially they allow for lowering the power in the carrier at certain times. This lowers the overall power consumption at the transmitter. However this could cause confusion for a receiver trying to demodulate the phase information from the main carrier because it will be varying in amplitude too due to the DCC. Therefore the type of Carrier control is signalled and the receiver can better decode the phase information if it can predict the amplitude variations due to carrier control.

[jbriggs]

I am moving this thread to general topics as I think it is of wider interest.

[DRM-Fan]

Originally posted by dk8cb


Vraiment !

A bit different on the new AMSS window in today's CVS release, see screenshot.

Roland

What new CVS release ? You mean Dream ? Is this 'available' ?

[DRM-Fan]

So RDS for AM then. Did'nt Germany want to use this (or similar) technology back in 1990 but could'nt for some reason ? One reason I think why Ofcom (name not this then) backed down from using c-quam for am stereo in the UK...

[dk8cb]

Originally posted by DRM-Fan
What new CVS release ? You mean Dream ? Is this 'available' ?

Dream's latest source code release is always available via the CVS (concurrent version system) and can be downloaded ('checked out' in CVS language) from cvs.sourceforge.net using a CVS-client of your choice. Of course you have to compile the executable from it.

Roland