[hpsdr] Possible added feature request

[Helmut Oeller]

Both ideas/approaches are unworldly. While the implementation of a VNA 
software is no big deal, a hardware reflection bridge has to be inserted 
and in particular calibrated.

But even when you get a reasonable result of R and jX  at your radio 
input, it's not enough information for an automatic tuner: the tuner's 
position in the feedline and the length of the feedline determines the 
necessary transformation. It would be much easier to utilize the SWR, 
e.g. available at a bidirectional coupler, used for the PS feedback loop.

73, Helmut, DC6NY


Am 03.11.2020 um 17:55 schrieb Scott Traurig:
> ***** High Performance Software Defined Radio Discussion List *****
>
>
> There was work in this regard done a long time ago but it is 
> hopelessly stale and it also requires additional hardware:
>
> https://openhpsdr.org/wiki/index.php?title=VNA 
> <https://openhpsdr.org/wiki/index.php?title=VNA>
>
> It would undoubtedly be easier to adapt a NanoVNA. Not only is the 
> hardware ready to go, the software is simpler and a lot more 
> accessible. It would be easy to embed in a home brew tuner:
>
> https://openhpsdr.org/wiki/index.php?title=VNA 
> <https://openhpsdr.org/wiki/index.php?title=VNA>
>
> Finally, it's worth noting that the only tuner on the market that 
> actually makes a complex impedance measurement and jumps right to the 
> exact answer in one step is the MFJ-939. If MFJ made a legal limit 
> version of that tuner I'd buy it in a heartbeat.
>
> 73,
>
> Scott/w-u-2-o
>
>
> On Tue, Nov 3, 2020 at 11:32 AM <radio at netins.net 
> <mailto:radio at netins.net>> wrote:
>
>
>     Pure signal uses one RX channel to provide feedback.
>
>     Is it possible to use an RX channel to determine just the phase and
>     resistance of the RF signal in the antenna system feed point?  If so,
>     this could be used to automate a home brew antenna coupler.
>
>     John,  W0GN
>
>
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