While seeking the source of interference on channel 11 in your 802.

While seeking the source of interference on channel 11 in your 802.11n WLAN running within 2.4 GHz, you notice a signal in the spectrum analyzer real time FFT display. The signal is characterized with the greatest strength utilizing only 1-2 megahertz of bandwidth and it does notuse significantly more bandwidth until it has weakened by roughly 20 dB. At approximately -70 dB, it spreads across as much as 35 megahertz of bandwidth.

What kind of signal is described?