A highly selective tuner can reject adjacent station interference. It does this by employing a narrow IF bandwidth filter. The downside is that sound quality can be compromised. Using a wide IF bandwidth filter will improve sound quality, but compromise interference rejection. The EXA tuner actually has two different selectable IF filters. If the tuner starts to pick up adjacent station interference, you can switch to the Narrow mode for lower noise and interference. If you drive into a less densely populated FM area, switch to Wide mode for improved sound quality. Or use the tuner in Auto mode-the way it comes out of the box. It actually senses when interference is encountered and will automatically switch from Wide to Narrow. There's about a 30dB improvement (± 200kHz) in selectivity between wide and narrow modes.

This is the first application of a variable selectivity tuner for mobile audio use and is one of the most significant improvements in mobile audio reception.

Sony tuners include advanced technologies to provide accurate, stable radio reception under actual driving conditions. Useful, intuitive features allow safe, convenient tuner operation while driving. The Sony tuner's ability to provide excellent sensitivity, selectivity and sound quality results from a combination of existing and Sony proprietary technologies.

X-Tal Lock Quartz Tuning uses a quartz crystal (X-Tal) which vibrates (oscillates) at its natural resonant frequency and stays exactly at one frequency without wavering. Then, all other radio frequencies are mathematically calculated (synthesized), using the quartz frequency as a reference. The result is extremely accurate frequency selection.

The Phase Locked Loop (PLL) sends the synthesized frequency through a comparator circuit, using the quartz crystal's oscillation as a reference. This insures the frequency and its phase are correct, resulting in stable, drift-free reception.