[hpsdr] Hardware pre distortion?

[k3it]

Helmut

I wonder what part of the Chris's message implied that he was "obviously"
not  satisfied with the pure signal performance? :)

At the bottom of this page
http://pavel-demin.github.io/red-pitaya-notes/sdr-transceiver-hpsdr/  there
is a screenshot of what looks like an excellent improvement after applying
the PS.

Also could you point to the discussion about losses in DDC/DUC chain in red
pitaya?..

73! Vasiliy


On Tue, Jun 28, 2016 at 1:04 PM, Helmut <dc6ny at gmx.de> wrote:

> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi Chris,
>
> Obviously you are not completely satisfied with Red Pitaya, the modified
> PowerSDR and PS. That’s no big surprise, but it’s a much better approach
> for
> linearization than that (strange) ‘hardware solution’.
> The efficiency of predistortion depends on the measurement precision of the
> actual TX signal and the reference TX signal or in other words the
> measurement dynamic range. Otherwise you can‘t precisely take correction.
> ‘Dynamic losses’ due to the necessary up/down conversion reduce the
> efficiency of predistortion dramatically. High losses in the Red Pitaya
> DDC/DUC paths limit the great performance of Warren’s PS algorithm. As the
> losses are 4 times more than in Hermes, I guess the improvement of IMDR
> results only on a limited correction in the upper part of the amp transfer
> characteristic. This also explains your observation of critical feedback
> levels.  An improvement/correction at low levels seems very difficult, so
> you should at least operate your amp with a high quiescent current.
>
> 73, Helmut, DC6NY
>
> -----Ursprüngliche Nachricht-----
> Von: Hpsdr [mailto:hpsdr-bounces at lists.openhpsdr.org] Im Auftrag von Chris
> Wilson
> Gesendet: Dienstag, 28. Juni 2016 15:49
> An: 'OpenHPSDR'
> Betreff: [hpsdr] Hardware pre distortion?
>
> ***** High Performance Software Defined Radio Discussion List *****
>
> 28 June 2016
>
>
> I hope this is a suitable question for this group? I am messing with a
> Red  Pitaya  experimental  board  and  a  special version of OpenHPSDR
> software  that  allows  pre distortion using "PureSignal" and it works
> very  well  once  the  feedback levels are set correctly. But i am now
> wondering  what the state of play is with hardware pre distortion that
> is software independent? Anyone got any info on this please? Thanks.
>
>
>
> --
>
>
> Best regards,
>  Chris                            mailto:chris at chriswilson.tv
>
> _______________________________________________
> HPSDR Discussion List
> To post msg: hpsdr at openhpsdr.org
> Subscription help:
> http://lists.openhpsdr.org/listinfo.cgi/hpsdr-openhpsdr.org
> HPSDR web page: http://openhpsdr.org
> Archives: http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/
>
> _______________________________________________
> HPSDR Discussion List
> To post msg: hpsdr at openhpsdr.org
> Subscription help:
> http://lists.openhpsdr.org/listinfo.cgi/hpsdr-openhpsdr.org
> HPSDR web page: http://openhpsdr.org
> Archives: http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/attachments/20160628/609ab2d8/attachment.htm>