What mode is this this waveform ?

k3Tim

The below waveform was seen on MW (around 550Kc) this morning. It appears a carrier is at 550Kc and a digital (DRM??) is above. The 'carrier' is still present hours later but no 'data'. The channel is clear now. Is it a DRM?

Thanks for any insight // k3Tim

David

Do you have and HD Radio AM station in the area?

Ria

You should be able to see the digital signal on both sides of an analog AM station. This is a local IBOC station, WCBS 880AM. Notice the digital signal on both sides of the analog.tal 

k3Tim

Thanks for the SSDR screen shot Ria. Checking for digital stations shows they are all are north in Los Angeles. Attached a screen cap from KNX AM-1070 which I believe shows the digital xmt on both sides of their frequency (1070kc). It's odd to watch as sometimes the right (higher freq) digital portion disappears and later returns. It also looks like their is some spill over from the station up the dial.
For the screen posted earlier, the signature looks different. As far as I can determine there isn't an HD AM station down the dial near the frequency and in fact 585Kc seems wide open. Will check during the predawn hours if the signal is present again tomorrow.