G
George
- Jan 1, 1970
- 0
Hi all, and Happy Holidays:
In the Los Angeles area several local AM broadcast stations appear to contain signals at between 100 Hz and 300 Hz away from the carriers, below the main program audio. I have called a couple stations to ask what these signals are, but they haven't called me back.
I'm wondering what they might be. In Europe there's the AMSS service that's used for low-speed remote signaling, and there's OFDM, but I didn't thinkthey are in use in the US. There's also a Nielsen TV rating signal that'ssometimes used in the US.
But does anyone have any idea what the signals probably are. A couple of spectrum plots are posted here:
https://dl.dropbox.com/u/2087421/carrier 870 spectrum - narrow.pdf
https://dl.dropbox.com/u/2087421/carrier 710 spectrum - narrow.pdf
Thanks
In the Los Angeles area several local AM broadcast stations appear to contain signals at between 100 Hz and 300 Hz away from the carriers, below the main program audio. I have called a couple stations to ask what these signals are, but they haven't called me back.
I'm wondering what they might be. In Europe there's the AMSS service that's used for low-speed remote signaling, and there's OFDM, but I didn't thinkthey are in use in the US. There's also a Nielsen TV rating signal that'ssometimes used in the US.
But does anyone have any idea what the signals probably are. A couple of spectrum plots are posted here:
https://dl.dropbox.com/u/2087421/carrier 870 spectrum - narrow.pdf
https://dl.dropbox.com/u/2087421/carrier 710 spectrum - narrow.pdf
Thanks