Jan 25, 2016

An e-Interview with Kenneth Wenzel

Mr. Wenzel @ Amsterdam RAI, 2015
As those of you, who read my blog, well know I have been interviewing about digital radio solutions. I made interview with the head of DAB & DRM organizations; namely Mr. Patrick Hannon & Ms. Ruxandra Obreja. I also had chance to speak with Mr. Attila Ladanyi, CTO of T&C Holding. The interview with Dr. Peter Siebert, CEO of DVB Project Office, was, some how, also on digital radio. 

Now, it is time to read another alternative approach. This time, I send my questions to Mr. Kenneth Wenzel. Many, know him as the man from Denmark, who tells that DVB-T2 Lite is enough for also digital radio. He is the CEO of U-Media ApS.

I had the chance to meet Mr. Wenzel twice, one in Tallinn in 2013 and the second in Amsterdam in 2015. I also had the chance to saw his demo in Amsterdam, showing that radio over DVB-T2 Lite, actually works fine even on cell phones. 

I personally want to thank to Mr. Wenzel, for his time...

1. Can you please, briefly explain the DVB-T2 Lite profile solution for digital radio and do you think that it could be the solution for a country which has not yet installed DTT network?

Since 1995 Denmark has tried to establish digital radio in the DAB format. The reason for the conversion to digital transmission is to achieve better audio quality, more stations and better resistance to multipath propagation, noise and co channel interference than in the analog FM radio technology. Opposite to FM and AM radio broadcasting with DAB technology you can broadcast more radio channels on the same frequency (a multiplex).

The introduction of DAB has not though been a success, because of some of the DAB channels are using a bit rate below 192 kbps in MPEG 1 Audio Layer 2 (MP2), which gives a poorer sound and specially a poorer stereo sound than the one available by the FM receiver under normal receiving conditions.

The second serious criticism against the DAB system is that it is to expensive to operate a DAB frequency network. Essentially because you have to use to much electric power (kW) and therefore you need bigger and more expensive transmitters to broadcast and receive programs with DAB.

DAB use a modulation form of radio waves that are easy to build receivers to, but causes that every one bit error caused by radio noise becomes two bit errors in the receiver. At the same time DAB uses only a single layer of rather weak bit error correction. To compensate DAB is broadcasted by a notable higher power than necessary.

Since DAB has not been a success, the radio organization WorldDMB has made a new standard DAB+, who use error correction in two layers. Besides the original error correction another error correction code called Reed-Solomon has been added. Unfortunately you lose 8,3 % of capacity when moving bits to this code, which means that DAB's all ready low use of bit rate is been further reduced. On the other hand more bit errors are corrected, so a weaker signal can be received and the coverage is getting better.

At the same time with DAB+ they introduced the possibility of using the audio compressing standard HE-AAC, which can be up to three times more effective. That way it is possible to transmit up to three times the number of radio channels in the same quality.
  
There is a technical problem regarding DAB+. DAB+ is broadcasted as DAB until the first layer of error correction and all the fundamental weaknesses in these parts of DAB is also present in DAB+.

Therefore when a long termed strategy for the digitalization of radio in Turkey is being made, different transmission standards as DVB-T2 and/or T2 Lite should be considered. DVB-T2 has a 3 times higher capacity than the DAB/DAB+ standard by the same broadcasting conditions.

T2 Lite vs. DAB+ broadcasted in the same 1,7 MHz channel raster

DAB has a capacity of only 1.152 kbit/s.

DAB+ has 1.152 kbit/s minus 1/12, which is used to the extra error correction. That leaves DAB+ with a bit rate of 1.152 * 11/12 = 1.056 kbit/s.

An equivalent DVB-T2 Lite transmitter with the same broadcasting strength and same fundamentally robustness would be able to transmit 3.201 kbit/s. DVB-T2 and T2 Lite would furthermore be better indoor and be less sensitive to for instance impulse noise (sparks).

If you just want to transmit 1.056 kbit/s you get 6 times better broadcasting strength with a significantly larger coverage.

DAB is as mentioned tied to MPEG-1 Audio Layer 2 (MP2), but DAB+ and DVB-T2 can transmit HE-AAC sound that uses less space and sounds a lot better.

With HE-AAC audio format a fair sound is available at 64 kbit/s.

With DAB+ you have room for 16 HE-AAC music programs at 64 kbit/s, and with T2 Lite you have room for 44 HE-AAC music programs at 64 kbit/s. If you use DAB, there is only room for 6 music programs at 192 kbit/s MP2.


2 Regarding the receiver side, are there any chipsets ready to support DVB-T2 Lite solution?

All DVB-T2 chip supports 1.7 MHz channel raster. The only thing to be done is that the software on the DVB-T2 receiver devices need to be updated to scan 1.7 MHz channel raster in VHF band III.

3 What should be done for the cars with FM only radios?

Last year in 2015 Sony, Parrot and Siano launched their new MRC diversity DVB-T2 chip for In-car Entertainment.

This technology enables a smart combination of the digital TV/ radio signals received via several antennas. Diversity-2 increases sensitivity that could triple the coverage area and offers better indoor reception (up to +70%). It also improves Doppler Effect handling (reception at higher speed). 

It is especially useful where robust reception can be very difficult to achieve.

And several German cars like the BMW 7 Type support already now digital radio as well as HEVC TV with DVB-T2 & T2 Lite.


4 Some claims that there no need for a new digital terrestrial radio, broadband and 4G/5G will be more than enough. How do you comment on that?

Internet radio is a great complement for niche radio.

I don't believe that it is advisable that Internet radio is the only platform for digital radio, even though it might technically feasible.

If you would like to know more, you can read these presentations by Kenneth Wenzel:

DVB-T2 Lite | Next Generation of Mobile Broadcasting
First Deployments, First Experiences
http://www.slideshare.net/KennethWenzel/dvbt2-lite-next-generation-of-mobile-broadcasting

and a more detailed presentation regarding T2 Lite vs DAB+ in VHF band III (1.7 MHz BW).


Is T2 Lite becoming the new frontier for digital radio?
VHF band III | T2 Lite vs DAB+

http://www.slideshare.net/KennethWenzel/is-t2-lite-becoming-the-new-frontier-for-digital-radio

I would like to thank to Mr. Wenzel, once again, for this important e-interview.


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