(Source: Radio World via Mike Hansgen)
LONDON — The BBC World Service, available on radio, TV and online, is part of one of the largest news organization in the world, the BBC.
The weekly reach of the World Service on all platforms accounted for 269 million (up from 246 million in 2015–16).
[…]Large numbers of the BBC’s audience still need international radio broadcasts.
[…]Right from its late ’90s inception, the development of Digital Radio Mondiale was fully supported and enhanced by the BBC World Service. DRM was seen as an efficient replacement for the analog AM transmissions. When we consider scarcity of spectrum for new uses and appreciate the characteristics of the radio broadcast bands, we recognize the tremendous properties these continue to offer broadcasters to deliver programs over sometimes very large distances and areas or in difficult terrain.
[…]The BBC is keen to exploit DRM in order to deliver, to key markets, BBC content free of gatekeepers in a form that can be accessed easily.
For that to be possible, the multi-standard receiver chip is required, and manufacturers must appreciate and act on this global market potential.
RonF
You obviously don’t know what backward compatibility means. xHE AAC receivers will decompress both xHE-AAC and HE AAC signals where as an HE-AAC receiver will not decompress xHE-AAC signals. Where is your profit will not? https://www.iis.fraunhofer.de/en/ff/amm/prod/digirundfunk/digirundf/dabdrmmplayer.html#tabpanel-5
Before you criticise the low bit rate transmissions on a new compression system you should listen to it http://www.drm.org. Most HF broadcasts are speech which is what xHE AAC is designed for but it can also automatically switch to HE-AAC mode for music.
https://www.nxp.com/products/media-and-audio/multi-standard-digital-radio/software-defined-radio-technology:SW-DEFINED-RADIO-TECH
https://www.iis.fraunhofer.de/en/pr/2016/20160310_KS_Software_DRM.html shows that it is a small change in firmware to adjust for different framing rates. The Inverse Fourier Transform function for COFDM demodulation and the Reed Solomon error correction is used in DAB+ and DRM. During encoding the audio is stored for varying durations depending on the mode of DRM and for DAB+ and then shuffled. The receiver has to reverse this process. This is easy for the microprocessor in the receiver and the firmware sets the amount of data hence the time stored.
The Titus II is now using the Fraunhoffer media player to decode the signals which includes decompressing it.
Lastly https://www.nxp.com/docs/en/data-sheet/SAF360X_FAM_SDS.pdf shows how firmware can not only demodulate, decode and decompress digital radio signals but also able to demodulate AM and FM in the same chip. HD radio has to be treated separately because of licencing agreements with xperi.
Correction: VHF 2 band should be VHF band 2 which is used for FM.
I should also add https://www.iis.fraunhofer.de/en/ff/amm/prod/digirundfunk/digirundf/dabdrmmplayer.html is now being used in the Titus II and can reproduce both DAB+ and DRM but not HD radio. That has to be a negotiation with Xperi Corporation.
RonF,
I have compared in detail the ETSI standards for DRM and DAB+. DRM now uses xHE AAC which is backward compatible with HE AAC used in DAB+. The error correction and modulation systems are identical. The only differences are the bandwidths of the signals which become firmware variables in the software filters, as is the amount of error correction and the number of frames to a super frame. The only real differences is the RF tuning to prevent interference from overloading the RF amplifier prior to analog to digital conversion. Since DRM requires a tuning range from 530 kHz to 230 MHz and DAB+ is only 174 – 230 MHz the receiver will have to switch between tuning coils under the control of the microprocessor. This is important in vehicles and high sensitivity receivers.
In automotive applications the shark fin antenna is useless at low frequencies including the AM bands so we may need to return to the motor driven telescopic metal antenna. This would greatly help AM against interference because there is no untuned antenna amplifier as in the shark fin antenna which all suffer from intermodulation distortion.
I have made no claims about compatibility of receiver designs for HD radio because it is a proprietary design and they will not publically release the complete system standards. For example the type of audio compression used. It was designed before 2002 so it will not be as good as xHE AAC for a start. There are also no published details on the error correction system used. How can you say that HD radio and DRM are similar? Different audio compression, DRM uses COFDM in one block of frequencies where as HD radio has a pair of blocks which are identical but phase inverted. As a result they will have to be processed separately in the inverse Fourier conversion from multicarrier to the IQ signals, where as DRM does not. The only real similarity is that DRM and HD radio can both operate in the Medium Frequency and VHF 2 bands. DRM can of course operate in the Low Frequency, High Frequency, VHF Low and VHF high bands as well.
I should also add that Xperi Corporation also charges a licence fee for the use of the HD radio standard on every HD receiver manufactured. Neither the DRM consortium or WorldDAB do this.
As or the number of new cars sold and registered in India, try doing that for the USA for HD radio it is a lot less than 14 %.
I will admit it is a long way to go for the 98 % in Norway.
AlanH, to avoid another endlessly fruitless discussion with you, I’ll just say this:
– Firstly, xHE-AAC isn’t really “backwards compatible” with HE-AAC. Depending on which of the 2 coding/framing formats is used, an HE-AAC decoder _might_ be able to decode the underlying HE-AAC part of the stream – but not the “x” extensions. In which case, you may as well be using HE-AAC at an equivalently-low bitrate, and forget xHE-AAC altogether. (I’ll also note that most current HE-AAC decoders aren’t even capable of that much…)
– Secondly, regardless of what you think you know, there are vast differences between the transmission coding & framing structures of DAB/+ & DRM30/DRM+. It’s not just a simple matter of “differences [in] the bandwidths of the signals”, or “the amount of error correction and the number of frames to a super frame”. All they really have in common is they both use COFDM at the physical level, and that DAB/+ & DRM30/+ both use a form of AAC at the audio encoding level. I suspect you’re missing a whole level of structure there, or assuming that either the encoded audio stream or COFDM itself includes that level.
And because of that gap in your knowledge & understanding, the rest is irrelevant…
Other than the frequency range used, the DAB+ and DRM have very similar processing. Those who are different is the old DAB and so if the UK decide to convert to DAB+ as a condition of an analog radio switchoff. This happened in Norway and is also happening in Switzerland, Germany and Denmark. There may be other European countries. The other exception is HDRadio who require licencing and keeps parts of the standard such as the audio compression secret.
What is required is a receiver which will tune DAB+174 -230 MHz, in in bands, DRM from 535 kHz to 1700, 2.3 – 26 MHz and 47 – 230 MHz. These radios need a colour screen to show the slideshow, Journaline and Emergency Warning System. The reception is available on a single chip except tuning, the processing for slideshow, Journaline and EWS is identical.
There is also a real requirement for a vehicle infotainment system to tune the above signals but commercial radio claims around 30 % of listening occurs in cars. There is 800,000 DRM infotainment systems in India in 18 months from the completion of their huge DRM rollout. DAB+ infotainment system are used in Europe and Australia.
The RTL receiver USB stick will only tune VHF and UHF but not lower, so it can only tune DAB+ and DRM+ channels.
With regard to the Dream software it does not include the decompressor. Whilst an HE AAC decompressor is on the web, but broadcasts using the newer xHE-AAC compression there is not any free decompressors on the web.
Huh?
Audio processing is very similar between DRM & DAB+ (well, identical in the case of HE-AAC). And the modulation is vaguely similar, in that both use COFDM (however there are major differences beyond that basic level).
But the rest of the transmission structure & encoding is vastly different between DRM & DAB+, and require completely different approaches. At that level there are more similarities between DRM & HDradio, or between DAB & DAB+ (which are, unsurprisingly, _very_ similar to each other). DRM+ is somewhere in the middle, with similarities to both DRM & DAB/+ but also very different to both (though, utimately, closer to DRM30).
There’s not really any “very similar processing” between them at all; at least, nowhere near as much as you seem to think from your previous comments.
FWIW, “800,000 DRM infotainment systems in India in 18 months” might sound a lot to Australian ears – but it’s only ~14% of vehicles sold in that time. Or about 0.3% of total vehicles currently registered…
The crazy thing is there are tens of thousands (most likely) of SDRs in use worldwide now, and they all can decode DRM now without any extra hardware. Just use the DREAM program and a virtual audio cable. So there’s a decent audience out there, especially in the US, that’s technically proficient enough to listen in, but there just aren’t any signals to decode anymore.
Seems like that user base should make up for the lack of radios at this point. DRM is never going to be a useful tool for broadcasting to Africa or Oceania except maybe to feed FM low power rebroadcasters a la RNZI. But some plucky broadcaster could certainly try out an occasional DRM broadcast to EU and the US for those of us with SDRs to have some higher quality audio to listen to occasionally.
The few times conditions have been good enough for me to hear RRI or Kuwait in DRM, it’s been a good taste of what is possible, and I’d like it if there was more to choose from.
DRM’s time has past. It was launched almost 20 years ago and what has happened in that time. At least 2 dozen member who were part of the consortium left as they saw no future. Countries that announced 15 years ago would be expanding DRM all pulled the plug and receivers? Where are the receivers?
Technology changes have taken place. If hey managed to get it off the ground in 1997 there would have been a better chance of it surviving. Yes it does sound fantastic when the engineering is correct. BETA was also a better video format than VHS, but VHS became the international standard.
I do agree that a multi-standard chip in a receiver would hasten the lowering of manufacturing costs, at least initially, which could spur consumption. I don’t necessarily agree with Nigel that a multi-standard chip is required, though, for successful adoption of DRM by the marketplace. As Nigel addresses, the feather in DRM’s cap is its flexibility in overcoming informational gatekeepers. Yes, a multi-standard chip COULD help adoption of DRM, but promotion of DRM’s strengths is more important in my opinion. Every time a corporation such as Facebook or a governmental agency like the NSA is exposed for spying, DRM’s prospects brighten.