Re: BFM Spectrum


kb3cs
 

U.S. major market (very large city) news & information stations do this. i discovered this the first time i was experimenting with decoding RBDS myself and following along in the specification document i got my hands on where it said use the 3rd harmonic of the 19 kHz pilot tone (!!).  but .. but .. i could clearly see the 57 kHz subcarrier and no 19 kHz ..   :-P

a week later i (figuratively) banged on the office door of a different station's engineer until they too noticed the subcarrier injection level of their 67 kHz reading service for the visually impaired was way too low and the service was therefore extremely noisy (program barely audible). i was dismissed on the first attempt to call their attention to the problem ("thank you for your interest" email), and later found a historical record of their MPX spectrum clearly indicating a 67 kHz subcarrier well above the noise floor. it took a further few days until magically the subcarrier level looked the same as it had a few years earlier.

  -73 C (-99 F)


On Wed, Dec 30, 2020 at 01:33 PM, jdow wrote:
The next interesting question is whether Simon's implementation can handle a station with RDS that is transmitting mono rather than stereo so there is no 19 kHz pilot tone. I notice the RDS specification contemplates this. But I rather suspect the number of stations actually doing this can underwhelm somebody who counts on the fingers of one hand.

{o.o}
[...]

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