DRM Overview: The Technology and the Transition Path To the Digital Future of AM

Harris Corporation

Introduction: Every new technology brings with it a combination of anticipation and dread: anticipation because no matter what the new technology is, its entire reason for being is that it promises new capabilities or overcomes some limitations, and dread because some degree of change will be required to realize the benefits. Mondiale (better known as DRM), one of the most significant breakthroughs in radio since the inception of , is no exception. As the next generation of AM radio, this digital, in-band system will give broadcasters and listeners capabilities that were unimaginable in an analog world. But to experience these capabilities, changes will be required. Broadcasters will need to upgrade their transmission facilities and even more importantly, listeners will need to upgrade their receivers—no small concern since the widespread availability and distribution of low- cost receivers has been one of the most important reasons why AM has long been the world’s most popular form of mass communication by far. This paper will take a close look at DRM, examining three key areas: First, the background, the technology and the anticipated global adoption of DRM; second, what will be required to upgrade a transmitter in general and a Harris DX transmitter in particular for DRM, and third, an overview of Harris’ DRM product platform—a platform designed to make the migration from analog to digital broadcasting as smooth and as cost-effective as possible.

1 I. The Background, the Technology and the Anticipated Adoption of DRM

DRM became a reality on June 16, 2003. On that day in conjunction with the ITU’s World Radiocommunication Conference in Geneva, Switzerland, 13 broadcasters from across the globe simultaneously initiated live, daily DRM broadcasts. As these first regular broadcasts—and also a number of special demonstration broadcasts--hit the air, there was no question that an impressive amount of work had been accomplished to take DRM from the minds of a small group of broadcasters and manufacturers who met for the first time in 1998 to an effective working system today. But what motivated the development of a new radio standard when AM radio— including the short wave, and long wave broadcast bands under 30 MHz— was already so popular? What technologies were involved? And how was DRM expected to be adopted worldwide? Let’s take a look at each of these questions:

The Development and Benefits of DRM

The formal development of DRM began on March 5, 1998 when 20 of the world’s most important broadcast-related organizations met in Guangzhou, with one goal in mind—to revitalize AM broadcasting by facilitating the spread of AM digital technology around the world. As they signed the Digital AM Memorandum of Understanding during the meeting in Guangzhou, these organizations put the development of DRM on a formal footing and took the first step toward its official inauguration. From the beginning, DRM’s proponents were committed to formulating a digital AM system design that could serve as a single, tested, non-proprietary and evolutionary world standard that would be market-driven and consumer-oriented. Conceptually, the new system was expected to deliver high quality mono sound with the advantages and the coverage of AM, using the same frequency assignments, supporting the same listening conditions (fixed, portable and mobile), and covering all listening environments (indoors, densely-populated cities with high electrical noise, sky wave and ground wave transmission paths, interference, etc.).

2 It was a given that resulting DRM receivers would need to be low-cost, consume little energy, and be easy to tune with selection by frequency, station name, or program type. However, while maintaining the best qualities of analog AM, the benefits of the new system would go far beyond improved sound quality. As a digital system, DRM would give listeners a more versatile receiver with ease of station selection, and new data services, both program associated (e.g., text information, station name, song title, performer’s name) and program independent (e.g., weather updates, other data services). DRM would offer many benefits to broadcasters as well. In addition to preserving the AM channel infrastructure (or even making it more efficient), DRM would enable some broadcasters with modern transmission systems to transition from analog to digital service with a relatively simple and cost-effective equipment upgrade in the field.

Bringing Together Field-Proven Technologies

DRM has managed to achieve all of these benefits and practicalities by combining a number of the most advanced signal generation and reception technologies, including: • AAC () • SBR (Spectral Band Replication) • for the Main Service Channel (MSC), Fast Access Channel (FAC), and Service Description Channel (SDC) • COFDM (Coded Orthogonal Frequency Division Multiplexing) • QAM (Quadrature ), and • Interleaving.

From the beginning, a key objective in the development of DRM was to design a digital system that works within the existing radio spectral mask without interference to the current analog signal. This was important because it would enable maximum use of the current AM spectrum without the need for any transition planning.

3 When Will DRM Become a Market Reality?

As with any new technology, the question of when DRM will become widely available to (and accepted by) listeners is one of the most important. Broadcasters will need to implement DRM on the transmitter side—a process that will vary in cost and complexity depending upon the AM transmitter and system that is already in place. Yet even when the DRM transmission infrastructure and programming are in place, the broadcast audience will need to be compelled to invest in DRM receivers, the final link in the air chain. Until there are sufficient listeners, DRM will remain in the experimental stage. To begin to predict when DRM will become a market reality, it is necessary to consider two things—first, when receivers will be available, and second, factors that are expected to compel listeners to invest in receivers in four defined “market groups.” Let’s start with the receiver question: at this time, there are only specialty receivers available. The first receivers were of test equipment quality and price. Now there are at least two moderately priced receivers available. One enables the broadcaster to listen to his transmissions and costs less than 1,000 Euros. The other, a software package made available by the DRM Organization (www.drm.org) for 50 Euros, is ideal for the technically inclined who already have a communications receiver want to experiment with DRM reception. The DRM Organization anticipates that the first commercial receivers will be introduced during 2004, with portable/mobile/car receivers to follow a year later (in 2005). DRM transmissions will ramp up with the commercial receiver launches, with a gradual increase in program hours following receiver penetration. Although DRM broadcasts have already started and business-to-business promotion efforts and demonstrations already are underway in Europe and Asia, the early mass market will develop in 2006. It is expected that a significant worldwide market for broadcasters, service providers and receiver manufacturers will be in place by 2008. But where, really, will DRM be established first? There appear to be four different groups of countries or markets for DRM, each with its own characteristics. Let’s briefly look at each of these groups:

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1) Saturated Radio Markets: This group includes countries where are available to most (or all) people in various formats. Most households have more than one radio, and there is a high penetration of car receivers. In these markets, broadcast sound quality is very important to the listener, who also has access to a variety of other media including home entertainment systems, personal/portable sound media, Internet radio, and other developed sound information and services. These countries already have (or will shortly have) established digital sound broadcasting systems against which DRM will have to compete. These countries also tend to be highly regulated, which means that it will take time to implement forms of DRM that require any reapportioning of the current frequency spectrum. Because these countries tend to have higher disposable income, they most likely will drive the first round of receiver development, since the first receivers will be higher priced than their successors. These initial receivers will be used in the automobile and the home.

2) Potential Radio Markets: Countries in this group have a structured radio broadcast service in place and generally are highly regulated. While it may take time for the regulatory bodies to accept the new technology, they will be motivated by the opportunity to improve radio service and to offer higher quality over AM channels. These countries tend to have less competition with other new and emerging digital media, and drivers for DRM will tend to focus on improving the existing service rather than on adding new formats and services. These countries also will most likely push the development of lower-priced portable and home receivers that are accessible to the masses.

3) Smaller Countries with High Income: In these countries where personal incomes tend to be high, receiver price is not expected to be much of an issue. Countries in this group tend to be developing rapidly and have a strong desire for news and other information. Digital competition also tends to be less significant in these areas.

5 Acceptance of DRM will be driven by available programming—possibly from distant countries. This group tends to be in line with early DRM adopters (Saturated Radio Markets) and will be potential candidates for the initial higher-priced receivers.

4) Countries with Low Income: These countries have a high dependence on radio for information and communication, and audio quality is less of an issue than in the other groups. There is little competition for the average listener who tends to have a relatively low income, and the price of the is very significant. Therefore, while this market is large, the transition will take time and most likely will only happen as the popularity of DRM broadcasts drives the availability and the cost of receivers to the current level of AM receivers worldwide. These countries will be the last to accept digital radio—even though the large size of this market makes it the most significant for the general acceptance of DRM.

DRM: One of Many Forms of Digital

DRM is one of three digital systems currently being pursued by traditional radio broadcasters. DRM and HD Radio (IBOC) are both in-band systems, and DAB (Eureka 147) is an out-of-band system. A brief overview of each system follows:

DAB (Eureka 147 Digital System) as a new transmission format in a new frequency band: • High quality • Rugged, reliable delivery • Flexible audio and data delivery • Easy-to-use receivers • MUSICAM® audio coding • Multiple program delivery coding and multiplexing • COFDM modulation • Requires new frequency band

6 HD Radio (iBiquity Digital System) for MW AM and FM • Uses existing AM and FM frequency bands • Designed to fit within 10 kHz (20 kHz total) RF bandwidth • Hybrid (combined analog and digital) and All-Digital modes • Allows for receiver transition planning • Blends digital to analog in the Hybrid mode • Digital quality FM stereo reception and high quality AM stereo reception • Auxillary data services

DRM Digital System as originally designed for LW, MW, and SW services • Uses existing AM bands below 30 MHz • Fits within service in areas using 4.5 kHz (9 kHz total) or 5 kHz (10 kHz total) RF bandwidth • All-digital transmission with multiple modes for high quality signals or difficult transmission conditions • High quality mono sound • Simulcast (analog and digital) transmission available, requiring additional RF bandwidth • Provides some data services

Harris—a company that has invested well over U.S. $60 million to offer the most comprehensive portfolio of digital transmission technologies of any broadcast supplier, is the only company to offer system solutions for DAB, HD Radio and DRM.

II. Upgrading the Transmission Chain to DRM

As broadcasters anticipate the eventual transition to digital radio, one of the most important questions has to do with the transmitter. Obviously it is important to ensure that the transmitter is capable of being upgraded for DRM simply and cost effectively in the field. Not all transmitters that are in use today are capable of being upgraded for digital operation, which depends on the ability of many individual DRM carriers

7 (approximately 200!) to accurately carry digital bits over the assigned bandwidth. To be DRM-capable, a transmitter must be able to meet stringent bandwidth, group delay and noise specifications, and offer a wide-range output matching network.

Harris 3DX-50 AM Transmitter This section will look at the suitability of the Harris DX Series all solid-state 10 kW through 2,000 kW transmitters for DRM. This line, which features Harris’ patented Digital Amplitude Modulation, is the focus for two important reasons: First, Harris DX systems are operating throughout China and, because of their prevalence, it is likely that many will eventually be upgraded for DRM throughout this country. Second, DX transmitters are of special interest because they are the world’s Number One line of Medium Wave transmitters. Well over 1,000 DX transmitters and “power blocks” in high-power systems are on the air, and the number is continuing to grow. These high-efficiency/low-maintenance transmitters are operating in environments ranging from deserts to sea-sides to extremely high altitudes and under the most severe conditions, including narrow band antennas, extreme high and low temperatures, high humidity, and power lines with spikes, glitches and brown-outs. Beyond operating flawlessly in the most demanding situations, these transmitters were designed to be compatible with digital systems and therefore, they provide a simple and cost-effective migration path to DRM.

8 Following are details that show why DX transmitters are ideal for digital operation in general and DRM in particular:

1) DX transmitters are inherently wideband. They provide both the wide RF bandwidth and the wide AF (Audio Frequency) bandwidth essential for digital transmission. Wide RF Bandwidth: DX transmitters use multiple stages of Class D RF amplifiers for high efficiency. A bandpass filter between each stage converts the square wave into a sine wave for the next stage. By carefully choosing low Q networks, Harris has designed the entire DX RF chain to be extremely wideband, from the external RF input to the RF output. Wide AF (Audio Frequency) Bandwidth: DX transmitters replace the traditional transmitter modulator with a full 12-bit Analog-to-Digital converter (A/D). The A/D converts the analog input signal to digital at either the carrier frequency rate or ½ the carrier frequency rate (depending on the transmitter’s operating frequency). Multiple low-power Read-Only-Memory (ROM) ICs (Integrated Circuits) decode the digital signal from the A/D and provide “turn-on/turn-off” signals to multiple RF amplifiers whose output is combined in a series combiner. The DX system of multiple ROMs and RF amplifiers form a high-speed “Digital-to-RF” converter to create the modulated RF output. Additionally, the DX modulation scheme also eliminates the traditional bandwidth-limiting low pass filter (and added group delay) used between the PA and the modulator in a PDM transmitter.

2) DX Transmitters provide low group delay. With the combination of techniques used to achieve wide RF and AF bandwidth, DX transmitters are highly linear. This is the most important characteristic of a transmitter that is well suited for digital broadcasting. The DRM signal is complex. It contains both amplitude and . In order to amplify this signal in a high efficiency AM transmitter, the DRM exciter breaks the DRM signal into two components. One is an amplitude component that is fed

9 into the AF input of the transmitter. The other is a phase modulated RF signal that is fed into the RF input of the transmitter in place of the usual RF source. In order to have a low Bit Error Rate (BER) and a clean occupied bandwidth, the amplitude and phase signals must arrive at the PA at the same time and with the correct amplitude for all frequencies in the total occupied bandwidth. To accomplish this, it is necessary to delay the modulation of the phase modulated RF signal. Some modulators do not have a constant delay over the complete frequency range, which could make them unsuitable for DRM. However, the modulator in the DX transmitter has very little delay and is essentially constant.

DX-200 AM Transmitter

3) DX transmitters maintain superior SNR performance. Because DX transmitters “turn on” (i.e., send voltages to) well-designed solid-state RF amplifiers in a “thermometer approach” (i.e., RF amplifier #1 is always #1; RF amplifier #2 is always #2, etc.) with sufficient cooling, module rotation is not required to prevent over- dissipation. Superior noise figures are preserved—even at low percentages of modulation. This is important because a high SNR can corrupt the digital signal and increase the Bit Error Rate, eventually affecting coverage.

4) DX transmitters include an exceptional wide-range output matching network. Designed to withstand VSWR conditions that will significantly compromise digital performance, Harris DX transmitters contain a full wide-range “Pi” (shunt capacitor,

10 series inductor, and shunt capacitor) output matching network with variable vacuum capacitors and front-panel tuning and loading.

Low-Cost DRM Conversion Process for Harris DX Transmitters

Any DX transmitter can be converted to digital transmission quickly, easily and cost-effectively using simple hand tools. The conversion process follows: (One important note: While the example shows the upgrade of a DX 200, 200 kW transmitter, the same process applies to any DX transmitter, regardless of power level. This is because all DX transmitters feature the same architecture. Higher power DX systems merely use more RF amplifiers with a bigger power supply and output network, while lower power transmitters use fewer RF amplifiers in smaller units.)

Analog Input Modifications: The analog input board provides analog signal input filtering, DC (carrier) power level control, and dither. The modification process follows:

Figure 1:

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Figure 1 shows the modulating analog input signal path. For digital broadcasting, the modified Bessel filter must be bypassed. The transmitter should be jumpered for DC coupled input since the exciter controls the DC (carrier power level) input.

The correct configuration is displayed in Figure 2: • C20 through C23 is removed. • L6/L8 and L5/ L7 are jumpered with a short circuit. • JP7 and JP8 is moved from AC coupled 2-1 to DC coupled 2-3.

Figure 2:

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Next, since the exciter provides the DC input that controls carrier power, the DC level normally supplied by the analog input board must be reduced. See Figure 3.

Figure 3:

At this point, measure the voltage at TP14 with a voltmeter. Record this voltage so if the transmitter is returned to analog mode, the test point will need to be reset. Adjust R56 counter clockwise to minimize the voltage at TP14.

13 A small amount of a 72 kHz “dither” triangle wave is added to the audio modulating signal for normal operation. To meet DRM spectrum requirements, this signal must be removed. Refer to Figure 4.

Figure 4:

Now, adjust R26 fully clockwise to minimize the dither signal to complete Analog Input Modifications.

Oscillator Board Modifications: The oscillator board normally supplies the carrier frequency signal used by the transmitter. It is replaced by the DRM exciter, which is connected to the external RF input on the oscillator board. Refer to Figure 5.

Figure 5:

14 Now, move jumper P3 from 1-3 (internal oscillator) to 1-2 to select the external RF input. Jumper P3 can be used to provide a 50-Ohm or high resistance load for the DRM exciter output.

Summary of DX transmitter conversion to DRM

The modification of a Harris DX transmitter for DRM operation can be completed with simple hand tools. The process normally takes less than 15 minutes to complete. If the station lacks a technical staff, these boards can be ordered from the factory through Harris’ module exchange program.

III. An Overview: Harris’ DRM Product Portfolio

In addition to its DRM-capable transmitter lines (Attachment A includes an overview of these lines which include DX, 3DX, and a new line of 1-6 kW DAX transmitters), Harris offers three key DRM products. These products include: • The Harris DRM content server, which provides encoding for one audio service and from one to four data services, multiplexes all of these services into one signal, and generates the signaling information required by the receiver to demultiplex and decode audio and data. • The Harris DRM audio server, which encodes one optional and additional audio service, and feeds the service multiplexer embedded into the DRM content server. Up to three audio servers can be linked to a single DRM content server for a four- audio service system. • The Harris DRM modulator, which provides channel encoding and COFDM modulation and feeds the AM transmitter with amplitude and phase signals.

High-level specifications are included in Attachment B.

15 Figure 6 shows Harris’ total DRM encoding, multiplexing and modulation system:

Figure 6:

GUI GUI (local or remote) (local or remote)

TCP/IP TCP/IP

Audio Audio pre-processing DRM TCP/IP DRM Data Content server modulator

Audio DRM TCP/IP Audio server

Audio AM DRM Transmitter Audio server

Audio DRM Audio server

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In addition to its DRM-capable transmitters and products, Harris currently offers a DRM Demo Kit for key customers who wish to evaluate the DRM performance of their transmitters. Additionally, Harris will offer DRM Upgrade Kits for of its DRM-capable transmitters and support services in mid-2004 in time for the launch of commercial receivers. A description of each kit follows: Harris DRM Demo Kit: Although the kit does not include the full set of features that will be available in Harris’ final DRM products, it does enable broadcasters to check the DRM performance of their current transmitters and transmission systems in real- world situations. The Demo Kit includes: • A basic DRM content server for encoding a single audio program and generating the signaling information. This content server is implemented on a laptop PC.

• A basic DRM modulator for channel encoding, COFDM modulation and amplitude and phase signal generation. This basic modulator can be implemented as a board that replaces the transmitter oscillator board in DX medium power transmitters or in a 48 cm, 2RackUnit (8.9 cm) chassis that can be installed directly in transmitters (e.g. DAX) or in a rack close to the transmitter (high power models).

• A test receiver with measurement capabilities from Fraunhofer (FhG Software Radio for DRM transmission), implemented on a laptop PC, with a RF front-head from AOR.

Harris Transmitter DRM Upgrade Kit: In mid 2004 in time for the first launch of DRM receivers, Harris will offer a DRM Upgrade Kits for Harris AM transmitters and upgrade services.

These kits will include Harris’ full-featured DRM content server, the DRM modulator, the transmitter upgrade procedure and required parts. Available services will include site review, training, transmitter upgrade and acceptance tests as needed.

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Conclusion

Even by the standards of today’s fast-paced world, DRM has developed rapidly. In only five years since the first planning meeting in China, the standard has been defined, the technology developed, and the first regular daily broadcasts initiated in Europe, Asia and North America. The first fixed receivers are being introduced in 2004, with portable/mobile/car receivers to follow in 2005. As early as 2008, it is expected that a global market for broadcasters, service providers and receiver manufacturers alike will be established.

There are probably many reasons why DRM is rapidly gaining a foothold:

First, by incorporating many of the most advanced technologies available, DRM truly does provide the means to improve the quality and the service capability of AM radio.

Second, DRM is an in-band system that preserves the worldwide frequency allocation infrastructure.

Third, DRM is an open, non-proprietary and evolutionary standard..

Naturally, however, broadcasters and service providers must be concerned about how they will eventually migrate to DRM. Many are wondering whether their current transmission systems will be able to be upgraded, and others who are considering investing in new systems want assurance that the equipment they purchase will not become prematurely obsolete. To know whether transmission equipment is upgradeable, broadcasters should pay careful attention to four important parameters—bandwidth (both RF and AF), group delay, noise, and output matching network. These specifications are key determinants whether a transmitter is suitable for DRM (or other digital) operation.

Since 1987 when Harris developed Digital Amplitude Modulation—the company has focused on developing transmission equipment that provides a smooth and cost- effective upgrade path to digital. Harris also has invested more than $60 million to offer broadcasting’s largest range of solutions for digital radio and television broadcasting.

18 As a result, the more-than-1,000 AM broadcasters worldwide who are operating Harris DX Series 10-through-2000 kW transmitters, 3DX50 transmitters, and now Harris’ new DAX Series 1-6 kW transmitters are ready for the DRM future. Moreover, drawing on its expertise in digital encoding, multiplexing, data broadcasting and modulation, Harris is developing a full line of DRM products including a content server, an audio server and a modulator. Harris is also offering a DRM Demo Kit that can enable key customers to test DRM with their actual transmission systems now, and will release an upgrade kit for Harris DRM-capable transmitters and support services in time for the commercial launch of DRM receivers in 2004.

Dax AM Digital Transmitter

There is no question that DRM is a reality and one of the most exciting developments in AM radio since its inception. Harris is ready and willing to be of service as broadcasters transition to the dynamic and exciting future.

19 Appendix A

Harris DRM-Capable Transmitters

Low power DAX Brand new modulation technology for high efficiency, 1-6 kW superior performance and low cost of ownership in the low power segment • Exceptional linearity and bandwidth • Digital Adaptive Modulation with digital adaptative correction • Broadband design • High efficiency (75%-plus) • Compact design • Digital ready (IBOC and DRM) • Internal DRM modulator • Internal or external DRM content server Medium DX10/15/25/50 Harris patented Direct Digital Synthesis for high power efficiency, high performance in the medium and high 10-50 kW power segments • Field proven technology (widest customer base in the world: 1500-plus units on air) • High efficiency (80% plus) • Digital ready (IBOC and DRM) • Internal DRM modulator • External DRM content server 3DX50 New 3D Direct Digital Drive technology for highest efficiency and auto serviceability • Exceptional linearity and bandwidth • Direct Digital Drive (no RF drives) • Auto servicing without reduction of the on-air power (automatic module re-assignment) • Hot pluggable modules • High efficiency (88%-plus) • Digital ready (IBOC and DRM) • External DRM modulator • External DRM content server High power DX100/200/600 • Same technology and same user benefits as the 50-2000 kW medium power DX series • Widest installed base worldwide • Available for LW transmission • External DRM modulator • External DRM content server

20 Appendix B

Specifications: Harris DRM Products

Content Server:

• Supports all audio encoding defined in the DRM standard (AAC, AAC+SBR, CELP, HVXC), for one audio service, at all encoding rates • Support of all data applications defined in the standard • Flexible data input format (TCP/IP based) • Generates the DRM multiplex, including the mandatory signalization in FAC, SDC, MSC channels • Supports MFN and SFN modes • Output compliant with the DI (distribution interface) standard (IP over Ethernet) • Synchronizable by an external GPS • Local and remote GUI for configuration and control • Support of dynamic reconfiguration • Full compliance with the DRM standards • 19” 2RU housing

Harris DRM Audio Server: • Supports all audio encoding defined in the standard (AAC, AAC+SBR, CELP, HVXC), one audio service, at all encoding rates • Output compliant with the DI (distribution interface) standard (IP over Ethernet) • Synchronizable by an external GPS • Local and remote GUI for configuration and control • Support of dynamic reconfiguration • Full compliance with the DRM standards • 19” 2RU housing

Harris DRM Modulator: • COFDM encoding and modulation fully compliant with DRM standard ETSI ES 201 980 • Supports all channel encoding rates • Supports all constellations and mappings (non-hierarchical and hierarchical)

21 Appendix B: Specifications for Harris DRM Products Page 2

Harris DRM Modulator (continued) • Supports all RF bandwidths • Supports all MFN and SFN modes • Available with digital mode and hybrid mode (simulcast) as an option • Input compliant with the DI standard (Distribution interface, IP over Ethernet) • Integrated GPS receiver for time and frequency synchronization • Output interfaces: audio and RF • Operational mode setting from the Content Server through the DI interface • 19” 1RU housing or add-on board for Harris DX transmitters • Local and remote GUI for configuration and control

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