[hpsdr] MDS and related architectures

[k3bu at optonline.net]

I stated IF...

Just playing RF Devil's advocate and wishing for the ultimate, not saying that SDR is not perhaps the best already. I saw what we measured with Leif, SM5BFC - SDR1000 vs. Orion.

Let me just extend the situations that I am wishing for the ultimate immunity in the contest station setup.

1. Out of band overload: having say 15 and 20 m beams on the same mast, transmitting kW on 20 and receiving at the same time on 15m.

2. Within the band overload: I am CQing, transmitting kW on 14.005 and want to receive at the same time, another antenna, same band, within 2 - 5 kHz of my own signal while CQing.

Some measures need to be taken to minimize the signals, but the point is that if we can integrate as much as possible into the RX design, so much better and flexible.

Again, big plus here is with computer control and incorporating filters and attenuator switching into the system will allow optimizing and setup for various gain antennas (small loop, Beverage, dipole, vertical, beams).

With SDR I am more excited than when I built my first SSB transceiver or Razor Beams.  We are talking another revolution and it is nice to be around for the taste of it! Can't wait to implement all that at www.TeslaRadio.org contest super station N2EE - NT1E.
 
Yuri Blanarovich, K3BU

----- Original Message -----
From: Robert McGwier 

>  Your statement that SDR is 
> not up to snuff yet on the RX is demonstrably incorrect and the 
> proof has been supplied by an outside agency in the ARRL labs if you 
> choose not to believe our own numbers.
> 
> 73's
> Bob
> N4HY
> 
> 
> k3bu at optonline.net wrote:
> > ***** High Performance Software Defined Radio Discussion List *****
> >
> >   
> >
> > -----------------------------------------------------------------
> -------
> >
> > >>Present receivers have dynamic range specified at about 20 kHz 
> and 2 
> > KHz, with state of the art SFDR around 95 dB and 75 dB 
> respectively.  
> > The close in dynamic range measurement shows the limited 
> performance 
> > of the 2nd IF within the passband of the roofing filter.  With a 
> > Mercury style SDR, the close in dynamic range never changes, the 
> > design gets close 100 dB all to way to zero offset. 
> >
> > The new SDR specification will look more like 130 dB SFDR at 10% 
> off 
> > frequency (due to the preselector) and 100 dB SFDR any offset 
> from 0 
> > to about 1-3% of frequency (in the passband of the preselector).
> >
> > jeff, wa1hco<<
> >
> >  
> >
> > I am looking forward to all this wunder stuff, just that from 
> the past 
> > experience, especially when the brutal signals are present from 
> other 
> > bands and within the band, even 2 kHz spacing specification 
> doesn't 
> > tell the real picture.
> >
> > Actually I was thinking of way of testing, more reflecting the 
> real 
> > life - rather than test at spacings of 20 or 2 kHz, use signal 
> levels 
> > of x, y, z and see how close we can get to the "signal in the 
> noise" 
> > without "humping" it. For serious contesting we are looking at 
> > spacings of 200 Hz on CW. Again, there are two major situations, 
> > strong signals from other bands and strong signals within the band.
> >
> > I guess the point is, if the pure SDR stuff doesn't cut it 
> (yet?), we 
> > should have the extra options available at the "switch" to kick 
> in as 
> > needed. Most likely candidate for the separate module.  By all 
> means 
> > let's have the most immune mixer with cleanest injection signals 
> with 
> > lowest possible phase noise.
> >
> > Yuri Blanarovich, K3BU, VE3BMV
> >
> >

 1155829459.0