What are the advantages of remote tuner architecture? Breaking away from traditional audio barriers

Overview

In traditional radio architecture, four antennas are connected toThe sound system required up to 20 meters (60 feet) of copper cable. The new architecture separates the tuner from the sound system, mounts it close to the antenna, and serializes the output. This reduces the length of the wiring to about one-fourth. The overall effect is a significant reduction in weight and cost, improved noise immunity, reduced heat, and reduced complexity within the sound system (Figure 1).

Traditional sound system architecture

The audio system is the command center of the car radio system, enabling the driver to select the audio source, set the volume, choose a song or select a radio station. Traditionally, in addition to audio signal processing and amplifiers, an audio tuner, baseband processing IC and application processor are also used, as shown in (Figure 2).

The complexity of traditional sound systems presents many design challenges. Heat generated by densely packed electronics can require the use of heat sinks and compromise reliability. The monolithic architecture of traditional sound systems also means that any change in radio characteristics requires at least a partial redesign of an extremely complex sound system.

As the primary user interface for a car’s infotainment system, the audio system is almost universally located in the center console. This location is very close to the driver, facilitating interaction between the driver and the audio system. However, it also places the audio system away from the antennas, which are typically located on the roof or rear/side windows. These antennas often require very long and dense wiring to connect to the audio system, which is more expensive and less noise-resistant.

(Figure 3) shows an example of a traditional architecture where two antennas are located on the rear window and connected to the center console audio system. Note that there are multiple cables running in parallel throughout the length from the antenna module to the audio system.

Remote Tuner Architecture

Maxim Integrated has developed an innovative “remote tuner architecture” that separates the tuner from the audio system. In the remote tuner architecture shown in (Figure 4), a pair of tuners are installed in each C-pillar of the car. The remote tuner modules are represented by RTB1 and RTB2.

A short coaxial serial link is used to connect two remote tuner modules together, and then the assembly of four tuners is connected to the sound system through a single coaxial serial link. This coaxial cable is responsible for connecting the tuner output to the sound system and providing I2C communication and power to the tuners, eliminating the need for additional cables. This architecture makes the sound system smaller, generates less heat, and greatly reduces the number of cables (Figure 5).

Digital serial connections have good immunity to environmental noise, greatly reducing the difficulty of wiring and improving the reception performance of weak signals.

Another advantage of the remote unit architecture is expandability - it is easy to add more tuners for background scanning and phase diversity without changing the sound system design.

Remote Tuner Demonstration System

The new architecture can be demonstrated using a pair of remote tuner modules.

The first remote tuner module (RTB16 in Figures 4 and 6) includes a pair of AM/FM/digital radio tuners, a serializer, and PMIC. This module supports both single-module systems and can be used in conjunction with a second module (RTB2 in Figure 4) in a multi-module system.

The second module (RTB27 in Figures 4 and 7) supports multi-module systems and includes a pair of tuners, power management, and a serializer/deserializer chipset that allows multiple modules to be daisy-chained.

The baseband/sound system adapter (Figure 8) includes a deserializer and connectors to easily connect to a baseband processor or logic analyzer for evaluation.

Additionally, the tuner module can be directly connected to any sound system with an appropriate GMSL deserializer and FAKRA connector.

The demo board includes six Maxim Integrated ICs (see the “More Information” section). Maxim's future plans are to further integrate ICs to provide smaller, more cost-effective solutions.

Summarize

We discussed the shortcomings of traditional sound system architectures and the advantages of adopting a remote tuner architecture, which moves the tuner from the sound system to a location closer to the antenna. Remote tuner architectures make sound systems smaller, generate less heat, and are more scalable, making it easy to add more tuners as current and future radio characteristics and frequency bands change.