Volvo XC90 owner manual Benefits of digital broadcasting, How HD broadcasting works, Limitations

10 Audio

Radio functions

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quency as the AM or FM station's present fre- quency.

The IBOC system is referred to as a "hybrid" since it is both analogue and digital. During hybrid operation, receivers still continue to receive the analogue (non-digital) signal. HD radio receivers incorporate both modes of reception, where the receiver will automatically switch to the analogue signal if the digital signal cannot be decoded or is lost by the receiver. When you have tuned to an HD Radio station,

the symbol will appear in the audio sys- tem display.

More information about HD radio and IBOC can be found on Ibiquity's website, www.hdradio.com and www.ibiquity.com.

Benefits of digital broadcasting

•Better sound (FM sounds near CD quality and AM as analogue FM).

•Some FM frequencies offer a greater num- ber of listening choices through “multicast- ing” (consisting of a frequency's main channel and any sub-channels that may also be available on that particular fre- quency. See also the section "Sub-chan- nels" below).

•When receiving a digital signal there is no multipath disturbance or hisses/pops/ crackling due to outside influences.

How HD broadcasting works

HD Radio works similarly to conventional radio and broadcasts of this type are available in many areas of the United States. However, there are a few key differences:

•Instead of transmitting one analogue sig- nal, stations send out a bundled signal – both analogue and digital.

•An HD radio receiver can receive both dig- ital and analogue broadcasts. Depending on the terrain and location of the vehicle (which will influence the signal strength), the receiver will determine which signal to receive.

Limitations

•Main channel vs. sub-channels (FM only): The main channel is the only channel that can receive in hybrid mode (both dig- ital and analogue). If a frequency has sub- channels, they are broadcast in digital mode only. The main FM channel will be displayed as, for example, 93.9 WNYC (Volvo uses the symbol > to indicate there are sub-channels available) The sub-FM channels will be displayed as 93.9 – 2 WNYC, 93.9 - 3 WNYC, etc.

•Reception coverage area: Due to current IBOC transmitter power limitations, the reception coverage area in digital mode is somewhat more limited than the station's analogue coverage area. Please be aware

that as with any radio broadcast technol- ogy, terrain, time of day, foliage level and building location can have positive or neg- ative effects on radio reception.

•Analogue to digital/digital to analogue blending: Analogue to digital blending will occur as the signal strength reaches a pre- set threshold in the receiver. This will be noticeable in fringe areas (areas with weak reception) and is normal.

NOTE

There may be a noticeable difference in sound quality when a change from analogue to digital or digital to analogue occurs, such as:

•Volume increase or decrease

•Equalizer settings, i.e., Bass/ Midrange/ Treble cut or boost

•Time alignment (Digital program mate- rial in extreme cases can be as much as 8 seconds behind the analogue). This will noticeable as a "stuttering" effect.

The above items are dependant on the broadcaster's equipment settings and do not indicate a fault in the vehicle's radio receiver or antenna systems.

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