XDRGuy, LLC

Modification, Repair, and Sale of the Sony XDR-F1HD Tuner

HD Radio's Extended Spectral Content

Analog FM frequency response is limited to 15 KHz. HD Radio can extend out to 20 KHz. If the station is paying attention to audio quality they can make full use of this capability of HD Radio. But some stations apparently run the audio signal through a brick wall filter to cut off everything above 15 KHz, as if it was analog FM. Other stations use the entire audio spectrum up to 20 KHz. See the spectral analysis plots below.

Above: Spectral analysis of music on KRVM-HD1. Note the audio content extends out to 20 KHz.

Below: Spectral analysis of music on KLCC-HD1*. Note the audio content does not extend beyond 15 KHz. *KLCC dropped HD service a few years ago.

XDRGUY, LLC / dave@xdrguy.com