The Sirius signal will carry only mild material and not programming aimed at teens 14 years old and up. That excludes the Cartoon Network's "Adult Swim" and Nickelodeon's "Nick at Nite." Disney will broadcast its East Coast feed. Drivers in California will see shows three hours before they appear on regular cable.
Mike Kasparian is market development manager for audio and infotainment systems with chip maker STMicroelectronics. He says creating a modulator chip to decode and display satellite TV in a car was "literally rocket science." The U.S. space program devised the signal-processing technique now used in Chrysler minivans.
Getting enough definition in the limited signal available to a moving car required an old trick from satellite communications called hierarchical modulation. In that process, a set of symbols within a data stream can cue an onboard system to automatically fill in additional information.
"By decoding, and decoding again, you artificially create this bandwidth," Kasparian says.
Chrysler and Tier 1 supplier Delphi are responsible for the in-vehicle hardware and the electronics that bring the TV signal into the rear-seat entertainment system.
The cars use two standard satellite receiver antennas, each smaller than an adult hand. They are spaced apart on top of the vehicle to improve separate audio and video reception. Signals from the compressed satellite video broadcast go to a separate video processing unit in the car. Audio is fed from the standard satellite radio system.
The components can be distributed around the vehicle for heat dissipation and packaging, rather than having to fit in the already-crowded instrument panel or overhead. That's only possible because they are wired to the controller area network, or CAN, bus. The latter is the computer backbone that connects microprocessors in the car.
The composite video feed itself, which requires bandwidth that would overwhelm the controller area network, is sent to screens over a dedicated wiring harness.
"The major aspect of why we went to CAN was to allow positioning of a lot of the bulkier parts of the units in other parts of the car," says Chrysler controller area network bus systems engineer Tim Potochik.
"Putting some of those things up in the headliner would have been a problem."