Digital radio

Under Digital Radio is the transfer of radio programs with digital transmission methods. In the coming years, analog processes are to be largely replaced by digital ones. In principle, digital radio could enable significantly more programs, interference-free reception and improved playback quality (see digital broadcasting ).

The designation "Digital Radio" (English, two words) has been registered since 2001, together with a logo, for the technical standard Digital Audio Broadcasting (DAB). The terms “DAB” and “Digital Radio” are often used synonymously in Germany and Switzerland. However, they are used somewhat differently in practice depending on the country. However, this article is more general about different types of digital radio, which includes DAB, among others.

The EU Commission proposed that analogue radio ( television and radio ) be switched off by 2012 at the latest. Germany initially planned to switch off analog broadcasting by 2010. All transmitters should replace the analog frequency modulation in the FM band with DAB at the same time . This time has passed and a new date has not yet been set.

It should be noted that broadcasting in Germany is regulated by the federal states and not by the federal government. In 2006 , the state parliament in North Rhine-Westphalia demanded a schedule for the introduction of DAB and the switch-off of VHF in cooperation with the other state parliaments ( see also analog switch-off ). On January 21, 2008, the commission to determine the financial needs of the broadcasters (KEF) decided to discontinue the financing of DAB with funds from the radio and television license fees. In contrast, the KEF has introduced the successor standard DAB + for national radio programs, u. a. by Deutschlandfunk and Deutschlandradio Kultur, subsidized with funds amounting to € 42 million.

For the digital transmission of radio programs , several mostly incompatible methods have been developed in recent years , which are optimized for different reception situations.

Terrestrial methods

Logo digital radio for DAB standard

Digital Audio Broadcasting (DAB)

DAB was also advertised as "Digital Radio" in Germany . So far, DAB broadcasting chains have been set up on additional frequencies (in TV band 3 and in the L band ) in Germany and Europe . At times there were up to 70 DAB programs across Germany. The largest selection was in Berlin, but after the start of DVB-T there was only one DAB ensemble left. A selection with more than one ensemble is still available in several Bavarian cities. In many federal states, however, only individual public service programs have been running since the private providers withdrew. Numerous programs previously broadcast in the DAB standard were converted to other channels in winter 2011/12 and can now be received on DAB +. There were only a few programs that were broadcast exclusively on DAB. With 80 percent coverage, DAB was considered to be the most advanced of all terrestrial digital radio systems until mid-2011. The procedure was chosen as the European standard. In principle, several stations are transmitted as a "DAB ensemble". One disadvantage is the Musicam audio codec ( MPEG-1 Audio Layer 2 or MP2), which requires a higher bit rate than Advanced Audio Coding ( HE-AAC or MP4) for comparable quality . (If you also include the error protection required for AAC in the calculation, you get a factor of 1.2 to 2 depending on the coded content) In the meantime, HE-AAC for DAB + (see below) has been added as AAC + v1 or AAC + v2 specified.

Digital Radio Mondiale (DRM)

Logo of the Digital Radio Mondiale

Digital Radio Mondiale (DRM) is a narrowband digital radio system for the worldwide, national, supra-regional and regional / local distribution of up to four offers ( radio programs with MPEG-4 HE-AAC v2 or xHE-AAC as well as data services and video formats) in a multiplex.

DRM encompasses the digital distribution of broadcasts via OFDM / COFDM transmitters in the AM range, i.e. on long , medium and short wave (called "DRM30"), with the four OFDM transmission modes AD and a bandwidth of 4.5 kHz 20 kHz, as well as in the VHF bands up to 300 MHz with OFDM transmission mode E (called "DRM +") and a bandwidth of 96 kHz; This means that DRM can be used in the VHF range (87.5–108 MHz) and, together with DAB / DAB +, also in VHF band III (174–230 MHz). DRM is an open ETSI standard and has been included in the ITU 's technical recommendations as a digital broadcast system for worldwide use.

The development and global market launch of DRM is supported by the DRM consortium , which was founded in Guangzhou / China on March 4, 1998 with the signing of an MoU by twenty of the world's most important international broadcasters, leading companies and organizations in the media industry and manufacturers of receiving devices .

In Germany, the German DRM Forum was founded in 2003 as an open association of interested market participants for the introduction of DRM in Germany.

A detailed description of the introduction and implementation of DRM beyond this article can be found in the DRM Introduction and Implementation Guide of the DRM consortium.

Digital terrestrial television (DVB-T)

DVB-T logo

Digital aerial television (DVB-T) is designed according to the original standard for television . From the beginning, the additional transmission for radio (for stationary reception) was provided as an option. Only the currently developed successor standard DVB-T2 makes it possible within the scope of its specification on the transmitter side to define transmission parameters in such a way that mobile reception is also possible, as is required for radio. Both standards are suitable for the transmission of up to 50 radio programs in a package on one television channel. For this purpose, a test ran until January 2014 in Berlin on TV channel 59, where a TV slot was occupied by eight radio programs. Due to the high UHF frequency and the low transmission power, however, there were relatively unfavorable conditions for this first DVB-T hearing test. In January 2014, DVB-T broadcasting in Berlin was ended.

The problem with conventional DVB-T is reception at high speeds (e.g. in the car radio outside built-up areas), as the system was not designed for this. Interference-free reception would only be guaranteed up to 80 km / h without great effort through so-called “diversity antenna systems”. The further development for mobile reception (DVB-T2) has meanwhile been completed, but the new system is not supported by the existing devices. Furthermore, there are currently no special radio receivers for DVB-T. The radio is received via the regular set-top box or a mobile DVB-T television receiver. A set-top box can not only be operated on a television set, but also on a normal stereo system in addition to or instead of an FM tuner.

Some European countries use DVB-T for radio reception, in Great Britain even in parallel with DAB. (For radio reception via DVB-T international: see list of countries with DVB-T operation ) In Austria, regional television was introduced with the third DVB-T transmitter chain in urban areas. With Radio Soundportal in Eastern Styria (Mur-Mürz Valley region) and Radio Maria Austria (Vienna region), the first radio programs can be received via this transmission channel since December 2009. In Germany, individual radio programs can still be received via DVB-T in the Leipzig area.

The directors' conference of the state media authorities has rejected nationwide radio via DVB-T. Quote: "The realization of a comprehensive radio coverage for in-house reception via state-wide or nationwide DVB-T networks can be ruled out." With the successful start of broadcasting of the nationwide DAB-Plus multiplex in August 2011 and the rapid follow-up by the state media authorities in winter 2011 / 12 the die seems to have finally been cast: DVB-T has established itself as a digital television medium, in all probability DVB-T will not play a role in the radio sector.

Simulcast process

In the USA , unlike other parts of the world, the IBOC (In-Band-On-Channel) technology was introduced instead of the DAB standard. The proprietary HD radio system from Ibiquity was standardized. In simulcasting, an analog and digital signal is emitted at the same time. Methods for FM and AM have been developed. In both cases, the bandwidth requirement increases by 50 or 100%. The advantage: Old receivers can continue to use the analog signal for a transition period, while newer ones evaluate the digital signal. IBOC offers several modes that give either the digital or the analog signal a wider spectrum. Either the digital signal is broadcast with good sound quality and the analog with a loss or vice versa. After a transition period, the plan is to switch to "All Digital Mode" and to eliminate the analog signal entirely.

The Swiss private broadcaster Radio Sunshine has been conducting trials with HD radio in Central Switzerland since April 2006. Tests have also been carried out in Paris since the beginning of 2006 with two frequencies. A test of single frequency networks (SFN) was planned for July 2006.

The FMeXtra process works differently . FMeXtra is a digital technology in which additional digital program signals are distributed via subcarriers of the existing analogue VHF transmitters, which can only be reproduced with special receivers. Tests have started in Norway and the Netherlands.

Terrestrial succession

DAB +

Logo digital radio for DAB +

DAB + is the further development of DAB with the improved AAC codec. This enables the distribution of more programs with better sound quality. Most older DAB receivers cannot process DAB +, however. So far, individual providers have promised software upgrades. Newer DAB + receivers (from 2010) are downward compatible, so they can also receive the older DAB format. The European Broadcasting Union has now specified the standard. Since August 1, 2011, DAB + has been used nationwide in Germany to broadcast national public and private broadcasters. The still patchy transmitter network should be fully expanded by 2015. In Switzerland, DAB stations were largely replaced by DAB + in October 2012 and are being discussed as a prerequisite for the final switch-off of FM. DAB + is already being used in other countries as well.

In 2014, 7.5 percent of households in Germany received radio via DAB. In 2015, ten percent of households in Germany received radio via DAB +, i.e. This means that around 4 million households in Germany received DAB + in 2015, around one million more than in 2014. In 2015 there were 6.4 million DAB + radios in Germany. Around 2 million of these are car radio devices, which corresponds to a growth rate of around 49 percent over the previous year. 4.9 percent of all car radios in Germany in 2015 were DAB + devices.

Digital Multimedia Broadcasting (DMB)

DMB is an extension based on the DAB basic system for moving pictures (video). This means that low-resolution (QVGA) television images can be transmitted integrated in DAB ensembles. A special form is also referred to as "visual radio", but technically consists of a DMB audio + video transmission with a very low data rate for video transmission. Conceptually, however, "visual radio" is not a radio, as it does not allow any radio functionality (e.g. traffic announcements). A lot of inaccurate rumors and misunderstandings are currently circulating here. DAB receivers sold to date cannot use DMB. The possibility of transmitting data services (slideshow, MOT broadcast websites, EPG, TPEG, ...) is already specified in the DAB basic system and the standards based on it and can also be easily adopted by DMB receivers. In Germany, 12 of the 16 state media authorities had spoken out in favor of testing DMB at the 2006 World Cup. A two-year trial phase is taking place in Regensburg. However, the four northern German states rely on DVB-H, as do 16 other European countries, three Asian countries and the USA. In addition to DVB-H, Austria, Switzerland and South Tyrol also rely on DMB and join the “MI FRIENDS” project in Bavaria. Due to different technical parameters and concepts, scenarios are likely in the future in which different standards (DAB, DMB, DVB-H, DVB-T, DRM, ...) coexist, are merged or at least can be used with universal receivers.

Digital Video Broadcasting - Handhelds (DVB-H)

This standard was developed for the IP -based transmission of low-resolution television images and multimedia content on cell phones. A combination with a mobile radio access for the transmission of interactive applications via IP Datacast is possible. DVB-H can be broadcast on TV channels combined with DVB-T. Many radio programs have already been transmitted in test networks. DVB-T devices cannot use DVB-H. DVB-H is already being tested in over 30 countries around the world and will be brought into regular operation in the USA, Italy and Finland in 2006. Regular operation in Germany should start in 2008. The operating company Mobile 3.0 has meanwhile returned its license to operate a DVB-H offer. The focus of previous efforts was also clearly on the transmission of television programs to mobile phones, and not of radio programs to car radios and portable devices.

DVB-H was also discontinued in Switzerland and Austria in 2010 and no new licenses were issued in Germany, so that DVB-H is considered to have failed in German-speaking countries.

DRM +

DRM + is a planned further development of Digital Radio Mondiale for FM . The system works with the AAC codec in a frequency -efficient manner, thus enabling many programs and particularly good playback quality. DRM + is thus positioning itself as an alternative to the slow-moving DAB. In contrast to the other technologies, the standard is also suitable for individual transmissions, so it is advantageous for local stations. However, DRM + is still in development. DRM + would be an option for the previously analogue VHF radio (87.5–108 MHz). In contrast to DAB, a coexistence of analog and digital signals would be possible here. An application in TV band I, which will soon no longer be used, or in the BOS 4m band is also being considered.

Future of terrestrial digital radio

Terrestrial digital technologies are satellite technologies for mobile reception e.g. B. superior in motor vehicles (no tracking of the antennas necessary, regardless of the weather). The existing close-meshed analogue VHF transmitter network can be converted comparatively inexpensively; DAB + enables a significant reduction in operating costs through “downsizing” (same range with significantly lower transmission power) and at the same time allows the distribution of additional programs and data services. Of course, the installation of DAB + tuners is currently still a considerable cost factor for end device manufacturers, especially in the lower price segment, which limits the rapid dissemination of corresponding receivers.

Stationary via satellite

DVB-S

Several million households in Germany can already use digital radio via satellite . With the worldwide standard for digital satellite television DVB-S, more than 100 radio programs come into the house. All you have to do is connect the digital satellite receiver to a stereo system. Alternatively, the radio sound can also run through the television speaker. The approximately 65 ARD radio programs except Next can also be received in high sound quality (320 kbit / s MP2 , all cultural programs except that of the NDR also in 448 kbit / s AC-3 ) via the Astra satellite , which is most used in Germany . So far, however, little is known about satellite radio and is only used in a few households. Mini transmitters enable the broadcasting of a signal for all radios within an apartment. In Europe, even more than 1000 radio programs can be received freely with a rotating satellite antenna. There are also more than 100 fee-based programs. So far there are hardly any DVB-S tuners that are designed for exclusive radio reception, but there are numerous models whose display on the front panel is used for basic functions such as B. Changing channels are sufficient. If possible, the digital S / PDIF should be used for transmission to an amplifier .

Astra Digital Radio (ADR)

ADR was a special form that was only broadcast via the Astra satellite . This technology was used almost exclusively in Germany. Around 50 programs could be heard. Since ADR only used the audio sub-carriers of analog television programs (instead of its own exclusive transponder), when they were switched off in April 2012, the broadcast of ADR was also ended.

Digital satellite radio (DSR)

The era of digital radio began in Germany with the digital satellite radio DSR, which transmitted a block of 16 radio programs at a high data rate without data reduction. The system was jointly developed by the German Aerospace Center (DLR), the Institute for Broadcasting Technology (IRT), the German Federal Post Office and German industry. The broadcast took place via the broadband network of Deutsche Telekom on the frequency 118 ± 7 MHz as well as the satellites DFS-Kopernikus and TV-Sat. The official start took place on the occasion of IFA Berlin 1989; it was shut down in Germany in mid-January 1999.

Mobile reception via satellite

These systems are suitable in areas with a low population density, but are rather unsuitable for Europe. Problems arise from the relatively low transmission power. In radiation shadows (e.g. in-house, canyons, underpasses, tunnels), reception is usually only possible to a limited extent or not at all.

SiriusXM (formerly Sirius and XM)

These two formerly competing systems offer around 140 radio programs via satellite in the USA and Canada for a fee, which can be connected to mobile receivers, e.g. B. car radios can be received.

Worldspace

Worldspace aims at Africa and Asia, but can be received as far as Central Europe with increased effort. Most of the 50 or so programs are encrypted and require a subscription.

DAB-S

Satellite systems for mobile reception of digital radio are also being discussed for Europe. Channels have been reserved for this in the upper L band . It is still unclear whether and when this technology will be used.

DMB-S

South Korea is a pioneer here. The country already uses DMB technology for its paid satellite system . MBSat1 is positioned at 144 ° East and uses a 12-meter antenna and 2400 watts to target Korea with 50 radio and television channels.

Due to financial problems, operations were stopped and the satellite moved to 75 degrees east.

Via cable

DVB-C

So far, more than 70 radio programs have been fed into cable television in Germany using DVB-C digital technology. Kabel BW currently feeds (as of September 2006) 221 radio stations, over 150 of which are free to receive. Vodafone Kabel Deutschland has been feeding all ARD radio programs as well as programs from Deutschlandradio and Deutsche Welle unencrypted into its cable network since February 4, 2008, and in full since April 29, 2008 . A smart card is required to receive the few private radio stations because they are encrypted . Most of the private channels broadcast terrestrially in Germany are also not digitally available in encrypted form on Kabel Deutschland. For reception, the set-top box must be connected to the stereo system or played back on the television.

Digital Audio Broadcasting (DAB)

In principle, DAB can also be transmitted via cable. However, there is no separate standard for this, but a standard DAB signal would be transmitted (fully compatible), in which the parameters are appropriately selected. However, DAB is not designed for the cable network in all respects; This is expressed, for example, in the fact that the error protection for a cable transmission would be better than necessary. Corresponding tests were carried out in 1998 with great success.

As one of the first cable network operators , UPC Switzerland announced at the end of September 2016 that it would feed the radio stations into the cable network via DAB + in addition to DVB-C . So far there has been neither regular operation nor the prospect of regular operation of DAB in cable.

Internet radio and streaming

With radio, the signals are distributed as a broadcast , while with streaming media , also known as streaming for short (e.g. web radio), the data is usually only sent out directly addressed to the recipient after a request. However, Internet radio is also often referred to as digital radio. The distribution takes place both terrestrially ( WLAN , WiMAX , UMTS ) and via cable (copper, glass fiber ), as well as via satellite. The format for transmission is not specified. The spread is practically the same as the spread of the Internet, which makes the "broadcast" very easy for radio stations. The technical effort involved in operating an "Internet radio station" is very low. As a result of these factors, the so-called Internet radio could gain great importance as digital radio. Pure internet radio devices are already on the market. More than 20 million people across Europe listen to Internet radio.

In addition, as part of its Telekom Entertain product, Deutsche Telekom AG plans to offer 2,500 digital radio stations in addition to digital television based on the DVB-IPI standard from December 2008.

Table overview

Transmission method for digital radio in comparison

Terrestrial

	DAB	DAB +	DRM	DRM +	DVB-T	DVB-H	DMB -T	IBOC-AM	IBOC-FM
developed for	radio	radio	radio	radio	TV	Multimedia	Multimedia	radio	radio
in operation in	Europe, Asia	Europe	worldwide	-	Europe, Asia, Africa, Australia	Italy, Austria, Vietnam, Albania, USA	Korea, Germany	United States	Switzerland (tests), Romania (tests), USA
Frequency band	Band III, 1.5 GHz band	Band III, 1.5 GHz band	LW / MW / KW	Volume II	Bands III / IV / V	Volume IV / V	Band III, 1.5 GHz band	MW	Volume II
Use of MHz	174-240 1452-1492	174-240 1452-1492	0.15-26.1	87.5-108 (planned)	174-230 470-862	470-862	174-230 1452-1492	0.5-1.7	88-108
mobile reception	optimized (band III) mE (1.5 GHz band)	Yes	Yes	Yes	yes, with current recipient	Yes	Yes	Yes	Yes
Programs can be received simultaneously at one location in D / AT	0	0-50	approx. 10	-	8 (in Berlin), 2–4 (in some central German metropolitan areas), 1 each (Styria, Vienna)	-	12 (Munich), 5 (several cities)	-	-
Audio codec	Musicam	AAC	AAC + SBR + CELP / HVXC	AAC	Musicam	AAC	AAC	HDC	HDC
Radio stations per multiplex	about 6	approx. 12	1-4	1 - approx. 5	approx. 32–50 (radio only) or a mixed bouquet with TV	about 100	approx. 10	1	1
Bandwidth per multiplex ( kHz )	1536	1536	4.5 / 5/9/10/18/20	50/100	6657 (Volume III) 7608 (Volume IV / V)	7608	1536	> 10	400
Frequency economy	O	+	++	++	+	++	+	-	-
Audio bit rate per program (kbps)	32-256	24-256	5-48	100-300	32-320			36?
best possible sound quality	++	++	O	++	++	++	++	O
Simulcast analog + digital	No	No	mE	mE	No	No	No	just	just
Single Frequency Networks (SFN)	Yes	Yes	Testing	Testing	Yes	Yes	Yes	mE	No

Legend : in my opinion = with restrictions, ++ = very good, + = good, o = average, - = bad
Bandwidth of DVB-T and DVB-H: table values apply to 8-k mode, in 2-k mode because of other carrier spacings slightly different: 6661 or 7612 kHz.
The information on DRM + are estimates, as the technology has not yet established itself as a standard.

Via satellite

	DVB-S	ADR (switched off)	S-DAB	S-DMB	XM / Sirius	Worldspace	DVB-S2	DSR (switched off)
developed for	TV	radio	radio	multimedia	radio	radio	TV	radio
in operation in	worldwide	Europe	-	Korea	North America	Africa, Asia, planned: South America	Europe (tests)	Europe
Waveband (MHz)	3500–4200 (C band) 10700–12750 (Ku band)	10700-11750	1480–1493 (L-band)	2630-2655 (Korea)	2320-2332.5 (Sirius) 2332.5-2345 (XM)	1469-1481	10700-12750
mobile reception	-	-	Yes	Yes	Yes	Yes	-	-
Audio codec	Musicam	Musicam	Musicam		AAC +	MP3	AAC	NICAM
best possible sound quality	++	+	+		O	O	++	++
Radio programs in D can be received	> 1000	approx. 70	-	-	-	7th	-	16
Audio bit rate per program (kbps)	32-320	192	32-256		64	64-128	variable	896