MVDR beamforming

Hi,
I have been reading a bit on MVDR beamforming. There are two things that 
I could not understand. One is, what is meant by output power when we are
talking about a receiver beamformer. Second is why should we want to
minimize it? We may miss the signal if outpower is less, right? 
Can anyone please help.
Thanks and regards,
Krishna.

On Oct 25, 6:12 pm, "Krishna_11_05" <mv_mail_box-jkri...@yahoo.co.in>
wrote:
> Hi,
> I have been reading a bit on MVDR beamforming. There are two things that
> I could not understand. One is, what is meant by output power when we are
> talking about a receiver beamformer. Second is why should we want to
> minimize it? We may miss the signal if outpower is less, right?
> Can anyone please help.
> Thanks and regards,
> Krishna.

The beamformer takes in data from N spatially diverse sensors and
generates one output signal. Its output power is minimized subject to
a "distortionless constraint" that sets the gain in the steering
direction to unity. The effect is to steer nulls into the direction of
interference, while preserving the response in the direction of
interest.

John

On Oct 25, 6:29 pm, John <sampson...@gmail.com> wrote:
> On Oct 25, 6:12 pm, "Krishna_11_05" <mv_mail_box-jkri...@yahoo.co.in>
> wrote:
>
> > Hi,
> > I have been reading a bit on MVDR beamforming. There are two things that
> > I could not understand. One is, what is meant by output power when we are
> > talking about a receiver beamformer. Second is why should we want to
> > minimize it? We may miss the signal if outpower is less, right?
> > Can anyone please help.
> > Thanks and regards,
> > Krishna.
>
> The beamformer takes in data from N spatially diverse sensors and
> generates one output signal. Its output power is minimized subject to
> a "distortionless constraint" that sets the gain in the steering
> direction to unity. The effect is to steer nulls into the direction of
> interference, while preserving the response in the direction of
> interest.
>
> John

In this context, "output power" typically refers to the expected value
of the squared magnitude of the signal in question (assuming it has a
zero mean). That is why it's called a Minimum Variance Distortionless
Response beamformer; as John said, the MVDR beamformer will minimize
the total output power (the signal variance) while keeping unity gain
(the distortionless response) in the steering direction.

Jason