[Elecraft] New DSP Idea

[David Woolley]

Assuming that there is enough processing power available, and the 
architecture physically allows the mixing, manually steering either the 
peak or the null should be achievable.  There is a slight subtlety in 
that one is trying to achieve a constant time delay at RF, not a 
constant phase change, but, if RF is sufficiently higher than the the 
baseband, it will be a good approximation, and the hardware devices 
being quoted probably have the same defect.

Automatically getting a direction is only accurately achievable if the 
interfering noise is isotropic, at least in the plane containing the 
line between the antennas. As such, it will not be able to automatically 
get a direction for an interfering signal, unless it can separate that 
signal from everything else, and if it can do that, there may be more 
direct ways of removing the signal.

The only way I can see of performing the computation is in the frequency 
domain.  Although everything starts as just a time delay, the down 
conversion preserves phase not time, so I think one needs to do a 
Fourier transform, rotate each value by a fixed amount (or one 
accounting for the offset from the carrier not being negligible) and 
then invert the transform.  (There may be better algorithms.)

Because of the discrete nature of FFTs, you would probably want to run 
several overlapping transforms and average their results.

I suspect the current DSP tries to avoid doing a full Fourier transform, 
and even panoramic adapter FFTs don't need to run overlapping transforms.

I think the big question is does the machine have enough processing 
power to do this.
-- 
David Woolley
Owner K2 06123

On 13/01/2019 01:06, David Gilbert wrote:

> these things:
> 
> 1.  Actually amplify a desired signal (probably 2 to 3 db) at the 
> expense of other signals or generalized noise from other directions. 
> Hams who put up phased verticals don't do it strictly for the transmit 
> gain.
> 
> 2.  Totally null out an offending signal or noise from a particular 
> direction.  Your brain most certainly can't do this.
> 
> 3.  Give you angle measurements in degrees.
> 
> As I said, I consider the add/subtract ability (#1 and #2) to be more 
> useful than the simple display of the phase difference (#3), but we 
> could have both.
> 
> Check this out .... https://tinyurl.com/ydfvcauz
> 
> It's a hardware implementation of pretty much the same as I'm proposing 
> Elecraft do in software, and the hardware version goes for $750.