Audio hum below EWR tower transmissions

[Moose]

So I've listened to Newark's tower for ages and have always wondered what that hum was that is always present when the controller is talking. I've heard it on several different radios and locations so I believe its originating from their equipment. It's almost a like a hearable PL tone. Any thoughts?

 

[nr2d]

Not a PL tone. Shouldn't have any hum on the modulation. Have you heard any aircraft complain about a hum?

 

[w2xq]

Wirelessly posted (Moto Droid Bionic: Mozilla/5.0 (Linux; Android 4.1.2; DROID BIONIC Build/9.8.2O-72_VZW-22) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/34.0.1847.114 Mobile Safari/537.36)

I heard that distortion back in the 60s. But it is communications quality and with audio filters the "problem" was moot. The only things on LW that deserve a wider filter were the European and African and Middle East broadcasters.