Motorola’s Symphony digital radio chipset delivers breakthrough AM/FM reception and performance

Christmas 2003 radios will receive more stations and sound notably better

Fans of AM/FM radio wanting to enjoy improved sound need not pay for satellite digital radio or wait for the introduction of land-based digital radio broadcasts. In a move that Motorola said would have significant repercussions for the digital radio industry, the company’s Semiconductor Products Sector has developed a new digital radio technology that enhances sound quality and improves signal reception for existing AM and FM analog broadcasts.

Designed for home and automotive stereo systems, Motorola’s Symphony digital radio chipset implements this new technology. The company said that listener benefits are numerous: less static, fading, pops and hisses; automatic tuning, so that adjacent stations won’t interfere with each other; extended listening range from existing signals; and overall improved audio clarity and volume. The bottom line: listeners can hear more stations, whether at home or on the road, tune to more remote stations with greater ease and enjoy higher quality sound.

Unlike other digital radio offerings, the new digital radio chipset does not require broadcasters to buy new digital broadcast equipment. Neither does it require consumers to pay a monthly subscription fee like those charged by satellite services because it operates on traditional AM/FM analog broadcasts.

“Symphony digital radio combines all of Motorola’s traditional strengths in semiconductors, communications and radios,” said Jim Turley, semiconductor industry analyst. “It takes familiar, age-old analog car radio and catapults it into a new age. Now humble car radios will compare favorably with satellite radio, delivering more stations, better sound and less interference—at almost no cost. It’s even upgradeable through software changes.”

Symphony digital radio technology, usable anywhere in the radio spectrum, is being applied initially in radio receivers tuning analog AM and FM signals. Impressed by the superior audio quality in tests against high-end analog sound systems, several consumer electronics manufacturers plan to introduce radios based on Symphony digital radio in 2003.

“In our quest to bring music lovers an ever-improved listening experience, we are always looking for new technologies that will help us advance sound quality and signal reception performance,” said Hyundai Autonet president J. J. Yoon. “Symphony digital radio is truly a breakthrough technology for the radio industry much as the CD was for the recording industry.”

Digital radio is a nascent and growing market. Today, there are an estimated 800 million analog radios in cars and alarm clocks, boom boxes and PCs throughout the United States. Two types of digital radio, satellite and land-based, have focused on transmitting digital formatted signals to radios equipped with digital receivers. Symphony digital radio allows listeners to listen to the stations broadcasting today, without changes at the transmitter. Overall, Allied Business Intelligence predicts that shipments of digital radio receivers in the United States will increase from 650,000 units in 2002 to more than 33 million units in 2007.

“Motorola’s extensive experience with digital audio has given us a keen understanding of consumer requirements and engineering challenges in the audio market,” said Motorola vice-president Bill Pfaff. “With Symphony digital radio, we have built on that experience and created a product that you have to hear to believe. We believe this product will change the way people listen to the radio.”

Behind Symphony digital radio

Motorola said that the key to Symphony digital radio’s performance leap is through frequency tuning: by software instead of the traditional analog means. Designed from 24-bit DSP architecture, Symphony digital radio uses software algorithms to tune, filter and improve the signal using methods that are impossible to implement via traditional analog circuits. One can simply download new software to incorporate new radio features and improvements.

Symphony digital audio has a long history of audio innovation and improvements in a variety of sound systems from music creation, mastering, commercial theatre surround-sound systems, to home entertainment systems, to digital audio players such as MP3, CDs and DVDs. The Symphony digital radio chipset can be used in a variety of radio models, from the feature-rich high- end systems to entry-level lower-feature versions.

Benefits include:

Range extension FM demodulator — The FM demodulator algorithm used in Symphony Digital Radio, which separates the FM signal from the carrier, provides superior range extension and improved signal-to-noise ratio under weak signal conditions over traditional digital demodulation techniques. In other words, this radio can pick up weaker signals from a greater distance and still provide sparkling clear reception. Essentially, the Symphony digital radio can find low-level signals that a standard analog radio cannot.

Better adjacent interference suppression — Adjacent radio signals often interfere with each other, not only because they are close together, but also because traditional tuning cannot lock onto a signal and hold it under changing atmospheric and terrain conditions. The variable intermediate frequency filter algorithm used in Symphony digital radio automatically adjusts itself to both 100 kHz and 200 kHz band channel spacing, while dynamically reacting to any changes in the environment.

Improved multipath interference suppression — In environments with mountains, hills, or tall buildings, radio signals bounce off hard surfaces and are reflected multiple times onto a receiver’s antenna. These reflections can interfere with each other and cause buzzing, pops, and sudden dropouts, phenomena collectively known as multipath interference. The Symphony Channel Effects Equalizer minimizes the effect of these many reflected signals for single antenna systems. Additionally, by utilizing two antennas, the radio can make intelligent decisions about signal conditions on both antennas to form a better signal with reduced fading.

Embedded radio data system/radio broadcast data system demodulation and decoding — The Symphony digital fadio baseband processor contains an embedded RDS/RBDS demodulator and decoder with error correction for those areas offering Radio Data System (RDS) information on FM broadcasts. Such broadcasts typically involve station and program identification as well as traffic information. Station and program information is used to provide frequency diversity for improved FM reception. The Symphony Digital Radio chipset can take advantage of this by performing fast Alternate Frequency switching inside the chipset, rather than by depending on the much slower system microcontroller to make such decisions.

Stereo separation — In addition, the Symphony digital radio provides improved stereo separation, often greater than 40 dB, thus exceeding the performance of current premium analog radios. The software architecture allows for audio processing and radio tuning simultaneously on a single processor/software thread. The baseband and audio processor can now handle dual audio streams. By using a software approach to digital radio implementation, Motorola is able to reach exceptional levels of digital radio integration in a smaller, lighter and far more flexible platform.

Dual source playback — The Symphony digital radio chipset solution can be configured for single or dual simultaneous source for playback. In a car, this means separate front and rear-seat audio, either two different radio stations or one radio and one CD input, for example. In the home, this means that different family members could use the same receiver to tune to their favorite stations in different parts of the house. The Symphony’s software architecture allows for audio processing and radio tuning simultaneously on a single processor/software thread. The baseband and audio processor can also handle dual audio streams. By using a software approach to digital radio implementation, Motorola is able to reach exceptional levels of digital radio integration in a smaller, lighter and far more flexible platform.

Improved flexibility — Radio manufacturers can develop new features through software programming instead of waiting for new silicon to be added, thus improving performance without enlarging the footprint. Manufacturers can tweak radio parameters, turn various algorithms on or off for experimentation, even develop their own algorithms and download them into RAM. A rich library of third party algorithms is available today through Motorola’s Symphony digital audio family. The Symphony platform provides sufficient program and data RAM for radio manufacturers to differentiate between their own radio models via different down-loadable features, or to distinguish themselves from other manufacturers by providing their own radio and audio algorithms.

Baseband audio processing — The baseband/audio processor also features a number of Motorola’s well-established “plug and play” audio post- processing features. Also, the open architecture of the Motorola DSP platform allows for third-party development of new audio algorithms. This combination creates a rich library of functions that radio manufacturers can use to differentiate their products. Some of these features include Bass Management, Delay Management, volume control, dynamic range compression, parametric equalization (EQ), graphic EQ, bass/midrange/treble control, loudness, speaker compensation, Dolby B Noise Reduction, Soundfield Processing, spectrum analysis and level display.

Baseband audio decoding — The baseband/audio processor provides embedded multi-channel decoding of 5.1, or six-channel decoding, Dolby Digital from DVD sources, as well as support for Dolby ProLogic II and DTS Neo:6 in order to create multi-channel surround-sound effects from stereo sources.

Technical features

The heart of the Symphony digital radio system is the baseband/audio processor. All baseband radio and audio processing is performed on this single chip rather than a series of chips. Highly integrated with advanced features, the baseband/audio processor reduces space and cost while providing a number of significant functions to enhance performance:

• one or two RF front-end chips with AM, FM and Weatherband tuning capability (200 KHz to 165 MHz)

• an all-digital DSP baseband/audio processor, including several special-purpose DSPs and one general-purpose DSP on a single piece of silicon

• an IF Sigma-Delta Analog-to-Digital (A/D) converter integrated with audio A/D and Digital-to-Analog (D/A) converters to transfer data between the RF front-end and the DSP back-end

• digital input ports and Enhanced Serial Audio Interface (ESAI) to connect external DSPs, Digital-to-Analog Converters (DACs) and other devices to easily accommodate additional features

• an on-board 6-channel Asynchronous Sample Rate Converter (ASRC) for interfacing to external digital devices, such as a MOST Bus or a DVD player

• an on-board Sony-Philips Digital Interface Format (SPDIF) receiver

Pricing and availability

The Symphony digital radio chip set is available now in sample quantities at a suggested retail sample price of $29.95 per three-part chip set. Volume production is planned for 2003.