Imagine a radio station that can beam near-CD-quality music from space to your car’s stereo without annoying static or commercial interruption. That’s what satellite radio is all about, and it has been a staple in the in-car audio landscape since the 1990s. But with streaming services like Pandora and Spotify on the rise, the days of satellite radio might be numbered. Here’s a look at how it became such an entrenched part of our driving experience, what it is today, and what’s in store for the future of satellite-radio listening.
Founded in the early 90s, both Sirius and XM have been broadcasting satellite-based digital radio service (DARS) from geosynchronous orbit for over two decades now. The idea was to offer unlimited access to a wide selection of channels with programming ranging from sports and news to classic rock and oldies. The company’s satellites operate at an altitude of about 22,000 miles (35,000 kilometers) above the Earth and transmit three signal beams, each with 60 channels or more, to overlapping coverage areas of millions of square miles.
The signals received by the satellites are digitized, error-corrected, de-interleaved, and decrypted by a baseband processor on the receiver. Then the data is transmitted over a Serial Peripheral Interface to the radio’s digital-to-analog converter for playback as analog audio. To ensure the integrity of the signal, the receiver contains a buffer that can hold four seconds of data when the receiver loses sight of the satellites. This has proven to be enough time to allow most subscribers to traverse underpasses or other obstructions without losing the signal.
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