[hpsdr] My doubts about I/Q beam-forming

[Robert McGwier]

Murray:

So long as the total bandwidth of the signal or band of interest is 
small compared to the carrier,   beam forming by adjustment of the LO's 
by analog phase shifters or by simple phase rotations in software all 
will work to do beam forming.   If you want you can read all sorts of 
literature about "narrow band" phased arrays.  Beam forming by simple 
I/Q rotation will indeed work so long as all the LO's, A/D's,  etc.  in 
the system of coherent.   They cannot be wandering around or independent 
of each other and still have the rotation by multiplication do beam 
forming.  So while not completely trivial in hardware,  it is a pretty 
simple concept.

Bob
N4HY



Murray Lang wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> My doubts about the ability to do RF beam-forming via I/Q have clarified 
> somewhat.
>
> Beam-forming would seem feasible given that you can modulate a carrier any 
> way you like with I/Q. However, the *resolution* of that modulation is 
> limited by the I/Q bandwidth and dynamic range. To accurately and steadily 
> control the phase of an RF carrier to within a small fraction of its 
> wavelength would require an I/Q  bandwidth of the same order as the RF.
>
> Would it not?
>
> Murray - VK6HL
>
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