DIGITAL RADIO GUIDE

TERRESTRIAL TRANSMISSION SYSTEMS - HD RADIO

stereo signal is digitally demodulated and demultiplexed by the FM receiver to produce a sampled, stereo audio signal.

The base band digital signal is first sent to the modem, where it is processed by the First Adjacent Cancellation system to suppress interference from potential first-adjacent analogue FM signals. The signal is then OFDM demodulated, deframed, and passed to the FEC decoding and deinterleaving function. The resulting bit stream is processed by the codec function to decompress the source-encoded digital audio signal. This digital stereo audio signal is then passed to the blend function.

Figure 4.15: FM hybrid IBOC receiver functional block

Tunable

sampled analogue FM FM

FM

Audio

Stereo

 

LO

 

 

Stereo

 

Blend

 

 

 

 

 

 

Det

 

 

Audio

 

X

BPF

A/D

DDC

FM

 

 

Isolation

 

 

 

 

 

RF Front End

 

10.7 MHz IF

 

FM+DAB

 

 

 

 

 

FAC QPSK/OFDM Deframe Demodulator

DSB

Stereo

Diversity

Delay

Audio

Decoder

FEC Decode

and

De-interleave

4.4.7Features Common to North American Digital Radio Systems

(1)Sound Quality

Sound quality of digital radio systems has improved dramatically in recent years with progressively lower bitrates being shown in various applications as achieving near CD quality. Rates well below 96 kbps are routinely utilized in digital radio systems in operation in North America and meeting with wide customer acceptance.

(2)Multipath Resistance

OFDM based systems are made to be resistant to multipath within a guard interval. In the case of the Eureka system, the guard interval is set to 62 ?s (18.6 km at the speed of light). This means that any echoes coming from up to 18.6 km will be considered as constructive to the signal. This allows the use of on-channel repeaters (that are treated as active echoes).

Note also that some systems, such as the Eureka system, also use unequal error protection and error concealment techniques. This allows for a graceful degradation of the digital signal quality when fading occurs and allows for S/N requirement reductions for the receiver. The Eureka system is especially noted for achieving multipath free reception, but narrower bandwidth systems such as the

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Grundig manual Features Common to North American Digital Radio Systems, Sound Quality, Multipath Resistance
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Digital Radio specifications

The Grundig Digital Radio represents a significant advancement in radio technology, combining aesthetics, functionality, and a user-friendly interface. As a pioneer in the audio and electronics industry, Grundig has successfully integrated modern digital capabilities into its traditional radio design, appealing to both nostalgic listeners and tech-savvy users.

One of the standout features of the Grundig Digital Radio is its versatility in reception. With DAB+ (Digital Audio Broadcasting) technology, users can enjoy a wide array of radio stations with superior sound quality, free from the hiss and interference commonly associated with analog broadcasts. The inclusion of FM and AM bands ensures that listeners are not limited, providing access to local stations that may not yet have transitioned to digital.

The Grundig Digital Radio is designed with ease of use in mind. Its intuitive interface, often featuring a clear LCD display, allows users to navigate through stations and settings effortlessly. Many models also include a built-in tuner that automatically scans and presets available stations, simplifying the setup process. For those who appreciate personalization, some variants come equipped with customizable presets, allowing users to save their favorite stations for quick access.

Portability is another key characteristic of the Grundig Digital Radio. Many models are lightweight and come with built-in handles, making them ideal for on-the-go listening, whether it's in the garden, on the beach, or during a picnic. Battery options, alongside mains power, ensure that users can take advantage of their radios wherever they choose.

In terms of sound quality, Grundig utilizes advanced audio technologies to deliver rich and clear sound. Enhanced bass responses and treble controls allow users to fine-tune their listening experience to match their preferences. Furthermore, many models feature additional inputs, such as AUX and USB ports, enabling users to connect their smartphones or other devices, expanding their audio options.

Other notable characteristics include built-in alarms and timers, which make the Grundig Digital Radio a versatile companion for daily routines. Some models even support Bluetooth connectivity, allowing for seamless streaming from a variety of devices.

In summary, the Grundig Digital Radio embodies the perfect blend of traditional radio appeal and modern digital technology, offering versatility, ease of use, superior sound quality, and portability to meet the diverse needs of today’s listeners. Its well-thought-out features and user-friendly design make it an excellent choice for anyone looking to enhance their audio experience.
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