remember back in the '60s and early '70s, some AM stations would broadcast
a short BEEP indicating the top of the hour. Sounded like a 1kHz tone,
lasting about a second. Like on WWV (a shortwave time standard reference
station). What sort of equipment was used to insert this BEEP? I had
assumed that it was an accurate timing of the top of the hour. Haven't
heard any stations do this anymore. Maybe PDs decided that the BEEP
was more annoying than useful to the audience?
I have imagined that the equipment used for the above beep might have
been just a filtered and gated WWV reciever (filter the audio to a very
narrow passband around 1kHz, have a local timing system mute the output
of this filter to create a small time window of plus or minus, say, 1/4
minute to allow the beep to go thru when WWV does transmit it, mute for
the rest of the 59 1/2 munutes to keep any possible noise from leaking
thru the filter and messing up the radio station's programming.)
I remember WKBW Buffalo, NY used to do this BEEP back around 1970.
Think some of the NYC news stations had it too.