[hpsdr] Selectivity design/measurement

[Ahti Aintila]

On 16/02/07, Robert McGwier <rwmcgwier at gmail.com> wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> I did all of these measurements on the alpha Janus and Ozy boards.  The
> AKM5394A is  one of the the  best recommendations I have ever given to
> any project or collection of projects and the Phil's and Bill and Lyle
> have a done a great job.   The Janus board lowers the noise floor of my
> SDR-1000 and that system is not SDR-1000 noise limited rather than Delta
> 44 noise limited and the "hump" is gone on my set up where I used to
> have a hump with my Delta 44.  I never had one with the Lynx L22 and it
> uses the AKM5394A with balanced inputs.
>
> I am in Boston all week at Mercury computing for Cell processor
> training  and will be at Virginia Tech next week at the wireless group
> but I invite any of the other developers to feel free to publish the
> numbers Hambly and I measured in the lab using the SDR-1000 and with
> with the fancy audio generators.
>
> Bob
> N4HY

Thank you Bob,

It would be interesting to have the measured figures and hard facts.
According to my rough estimations based on the specifications of the
AK5394A, its noise figure should be about 20 dB. This means that
considerably less gain of SDR-1000 is necessary for low noise/wide
dynamic range applications of the radio.

A couple of years already, I have been even considering of modifying
my Waveterminal 192X sound card to have direct access to the balanced
input of the ADC. That may be a "poor man's" alternative to the
Atlas/Janus/Ozy combination. Then came the idea of the HPSDR with the
AK5394A and I decided to wait.

I am going to purchase two sets of fully assembled Atlas/Ozy systems
and continue experimenting with the Waveterminal some time later.

73, Ahti OH2RZ


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