Frequency diversity is the sending of the same information using two different frequencies of transmission or two different transmitters set to different frequencies. The idea is that the receiver(s) will choose which frequency has the better signal at any given moment and use that as its preferred signal. This is a method that is independent of spatial diversity (two spaced antennas). It is in fact possible to use both spatial and frequency diversity and gain benefits from both. It does require two transmitters and two microphones but it gives a substantial increase in redundancy and immunity to drop outs. See page 19 of the Venue receiver manual for more information.