One can listen to an iPod in the car through FM modulators, cassette adapters, line-in connections, Smartphone systems, USB cables, media gateway cables, CD player cables and smart-cable connections. Some iPod playing devices work best only with iPods, while others support different kinds of digital music, making them good choices for a complete sound system.
FM modulators transmit sounds from iPods through the car speaker system using a simple cable. The cable connects to the iPod and FM stereo. The stereo plays iPod songs on unused radio frequencies. Some cables plug into cigarette lighters for power, while others require batteries. Newer cars, such as those with XM satellite radio and Sirius, come with integrated cables, letting users hook up iPods without performing installation. Cassette adapters sync iPods with older car stereo systems. Antenna direct connections transmit songs over FM frequencies. They link between the radio system and antenna to produce clear sounds.
Smart cable connections come in the form of modules that connect iPods to car CD changers. These devices, along with media gateway kits, perform double duty of playing iPod songs and charging the iPods, making them practical choices. Some, like Bluetooth and Smartphone systems, let people play iPods through specific devices, while others, like cables, work with generic radio systems.