[hpsdr] I didn't think it would happen again "PING"

[Murray Lang]

The beam forming had occurred to me as well, but I was interested in the 
gain. With lot/block sizes shrinking and everyone becoming more precious, 
towers with HF beams are now virtually impossible to get approved. However 
four verticals might be more achievable. Each could be fed with a 
controlled phase shift to give roughly 6dB gain (I would have thought). 
Each could also have its own PA, making higher power easier to achieve in 
some ways. For mobile operation the control unit could be fed with a gyro 
to correct for the vehicle/vessel orientation.

I suppose this could be done with four synchronised receivers transmitters, 
with the phase adjustment performed at I/Q level. However, would it be 
feasible to have  outboard units based on the LT2208, a D/A of some sort, 
an FPGA and a big memory stick? I imagine the memory speed would limit such 
a device to HF operation.

Just a (apparently unoriginal) thought.

Murray VK6HL


At 10:16 AM 19/08/2006, jeff millar wrote:
>***** High Performance Software Defined Radio Discussion List *****
>
>Eric Ellison wrote:
> > How are our lurkers doing? Anyone have any ideas for me to synergize us
> > again?
> >
>Here's some ideas:  Extend the SDR concept to multiple antennas with
>digital beamforming.  Some snippets of ideas...
>
>     * Four channel receiver with each channel connected to a vertical in
>       a four square.
>     * Remote receivers that use 802.11 to link sections of the band back
>       to the DSP, such at 3780-3800 KHz
>     * Rx with 802.11 has whip, preselector, preamp, A/D, DSP, uproc, USB
>       802.11 dongle, battery powered, clocks synchronized by 802.11
>       messages.
>     * Networked receivers, like IRLP/Echolink on steroids, link 10-20
>       kHz of passband in I/Q and let DSP tune with the band, DSP can
>       also combine signals from distributed receivers
>     * Lay out an array of remote receivers with small whips and beamform
>       using all the elements of the random array.
>     * Combine beam forming and interference nulling to maximize SNR
>     * With an array of whips, null interference in both azimuth and
>       elevation
>     * For all the signals in the passband, separate them by direction of
>       arrival and simultaneously beamform and interference null on _all_
>       signals.  Then demodulate all signals.  The output of the receiver
>       becomes separate, selectable, audio channels for each signal.
>
>For the mathematically inclined, the paper below suggests some DSP
>approaches to beamforming on all signals simultaneously.
>
>     www.nps.navy.mil/asilomar/asil03/prog03/Asilomar-Keynote.pdf
>
>Look at the slides on "blind signal separation" and "principle component
>analysis".
>
>jeff, wa1hco
>_______________________________________________
>HPSDR Discussion List
>To post msg: hpsdr at hpsdr.org
>Subscription help: http://lists.hpsdr.org/listinfo.cgi/hpsdr-hpsdr.org
>HPSDR web page: http://hpsdr.org
>Archives: http://lists.hpsdr.org/pipermail/hpsdr-hpsdr.org/



 1156209314.0