Monitoring mode gets frames from more than one channel!

[Ajeet Nankani]

Even though i am monitoring on particular channel(channel 1), but i also
get frames(not all but most) from AP operating on other channel(channel
6).
Why is like that?
What to do to capture frames "only" on particular channel?

I have prism2.5 based card and using ethereal to capture the packets.
first i set it in monitor mode by
iwconfig wlan0 mode monitor
then i set the channel
iwconfig wlan0 channel 1

Thanks.

-ajeet.