[TowerTalk] receivers for HF phased array

[Rick Karlquist]

Jim Lux wrote:
> Folks, I'm looking for receivers for a HF phased array (they can be
> transceivers, though).  Here's kind of what I'm looking for:
> Everything locked to a single oscillator in the receiver is a plus (makes
> calibration easier). Even more of a plus is if I can modify it to accept
> an
> external oscillator (of whatever frequency is needed).

It's not that simple.  Merely being able to lock the *frequencies*
together does nothing to address phase.  You will get random phases
that change every time you tune the frequency synthesizers in the
receivers.  You would have to measure these random phases on a real
time basis and correct for them.  Then there are the 2nd and 3rd
LO's to worry about too.

I think what you really need to do is use single conversion receivers
and provide the actual LO to the receiver externally.  I don't see
any way you can leverage off the shelf receivers to do this in any
way that would be cheaper than just building your own receivers purpose
built to be phased array receivers.

The exception to this would be if you could find receivers that are
exclusively based on DDS LO's.  Those LO's are phase coherent.  However,
I would be surprised if anything off the shelf totally avoided
phase locked loops and divide by N's.

Let us know if you come up with anything having complexity within
hobby parameters, as opposed to what the govt can afford.

Rick N6RK