10m DX using the ZeroFive Antennas ground plane antenna.

This video is a recording of part of a contact with a station in New Zealand where I was using the 10 - 40 meter ground plane antenna. This is the first DX on 10 meters that I've worked using the ground plane antenna.
You'll see a big 'hump' of noise around 28.450mhz. I'm not sure what this is. It doesn't appear when I use the wire antenna so perhaps the vertical is closer to the noise source that the wire antenna is.