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Upbeat contemporary and "classic pop" music. No announcements so far. Probably from the Netherlands. There is a long standing theory that American DAB (HD) has a self-noising property. Some more detail can be found here http://ham-radio.com/k6sti/hdrsn.htm
An HD Radio station's digital sidebands may interfere with reception of its own analog signal in two ways. First, FM detection of the sidebands may generate intermodulation products that overlap the analog signal. Interference also may occur when the stereo decoder demodulates the digital sidebands along with the stereo subchannel signal. Because the digital subcarriers are numerous and their data randomized, analog detection yields noise. This form of HD Radio self-noise is the subject of this article.
Also within the last few years, the Arbitron PPM system has been toyed with by several manufacturers in an attempt to boost the host stations' ratings. They do this by making the PPM signal louder, and in many cases unmasking the tones. It seems to be most noticeable on dry voice, and makes the announcer sound as if they are in a broom closet, or talking through a paper towel tube. The device responsible for this is made by Telos, called the voltair. https://www.telosalliance.com/25-Seven/Voltair
Employing a clipper as a peak limiter in a HD Radio system will work, but there are sonic penalties to be paid. Any clipping process yields harmonics of the fundamental source signal, and even with distortion masking some second order harmonic content will remain. This adds to the audio spectrum and aggravates the encoder, which in turn spawns additional sonic artifacts. This is particularly noticeable in the high-frequency range – where most codec artifacts exist – and is very noticeable with certain program material; therefore, another form of peak limiter is needed.
Has been on the last two days - 11650khz - as early as 1850z as late as 2010z - 12/7 and 12/8.
FPE
