Maxim proposes distributed reception for automotive radios


Maxim trad head unit architecture“Traditional radio architecture (right) brings many challenges to designers. The vehicle’s complex head unit must accommodate multiple tuners, manage heat dissipation, and receive multiple cables from the antennas,” said the firm. “In addition, the received analogue signals pick up noise as they travel from the antenna to the head unit of the vehicle. Finally, baseband processing uses single purpose hardware, requiring separate designs to support multiple worldwide radio standards.”

Maxim remote tuner architectureIn Maxim’s scheme the tuners are re-located close to the antenna, where RF noise is presumed to be lower.

The tuners are constructed around the firm’s MAX2175 chip (see below) which has connections for receive antennas that cover analogue and digital broadcasts: L-band, VHF, FM and AM (and DRM digital-in-AM-band). There is a separate RF amplifier for each band.

Reception of FM, DRM+, FM-HD, and Weather-Band is supported using a low-IF and digital conversion to baseband. AM (long, medium and short wave) and DRM reception is using direct sampling and digital conversion to baseband.

MAX2175The bit streams are launched to the head unit through a single coax cable, which also serves to provide power to the tuner. Serdes activity in the design is handled by the firm’s 14bit GMSL serialiser/deserialiser pair.  The proposal includes one MAX2175 per band (see top diagram).

“Not only does this improve radio performance, but it also reduces the weight of the vehicle,” claims the firm. “In a 4-channel radio, for example, 4W of power can be removed from the head unit.”

MAX2175 block diagramAs a baseband processor, Maxim is proposing, for example, Renesas’ R-Car H3 SoC. “This software-defined radio approach enables flexible implementations by eliminating the need for a dedicated baseband processor. By changing the software, any worldwide radio standard can be supported using the MAX2175,” said Maxim.

Depending on vehicle needs, more or fewer remote tuners would be installed.

Fraunhofer IIS is working with Maxim on SDR. “Together with Maxim, we developed a complete software defined radio solution which demonstrates a clearer radio signal for automotive applications,” said Fraunhofer head of infotainment Martin Speitel. “The development kits for software-defined digital radio from Fraunhofer IIS are specifically designed for best-in-class performance.”

Maxim has a remote tuner video.



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