NPR and Dynamic Range question


Zacharias Liangas
 

Hello again

In my previous post in ‘Cross SDR operation and FDM”  I have seen a reply from Clint Chron  referring to NPR a term I meet for  first time. Based in the context  I understand that is somehow related to Dynamic Range of older analogue receivers.What is the difference and similarity between these two terms?

Here is his email:

The Elad Duo and S2 radios have significantly better overload performance than the RSP1A.  I have all three radios.  The Elad NPR performance is in the low 70s and the RSP1A is in the high 40s.  Most older analog HF transceivers have NPR figures in the mid to high 50s.  The very best high end SDR transceivers (Flex, Icom, Yaesu, and Anon) have NPR figures in the low 80s.  BTW – the same holds true for 3rd Order IMD performance of the mentioned radios.


By the way I tested a loaned  Airspy Discovery from a friend that overloads with my 2x16 m antenna with all RF settings off  (ATT , AGC ,preamp ) Two reviewers advised that didn't happen to them , Ther are here many signals between -50 and -35 dbm on local  nights /UTC+3. 
I don't know what can mean to you but for me it seems it is either 'damaged' or the its old called dynamic range is limited. 


Alan
 

Zacharias

I have seen a reply from Clint Chron referring to NPR a term I meet
for  first time.

Same here, I've never heard of it.

By the way I tested a loaned  Airspy Discovery from a friend that overloads with my 2x16 m antenna with all RF settings off  (ATT , AGC ,preamp )
Any radio can overload if given a big enough signal.
Are you saying you turned off the AGC and used it without any attenuation?
The Airspy is good for a relatively cheap SDR but it has it's limits.

73 Alan G4ZFQ


Andreas Rehberg
 

 
some details can be found here:
 
 
Andy, DF4WC
 
Gesendet: Mittwoch, 29. April 2020 um 08:54 Uhr
Von: "Alan via groups.io" <alanzfq@...>
An: EladSDR@groups.io
Betreff: Re: [EladSDR] NPR and Dynamic Range question

Zacharias

>I have seen a reply from Clint Chron referring to NPR a term I meet
for  first time.

Same here, I've never heard of it.
>
> By the way I tested a loaned  Airspy Discovery from a friend that
> overloads with my 2x16 m antenna with all RF settings off  (ATT , AGC
> ,preamp )
>
Any radio can overload if given a big enough signal.
Are you saying you turned off the AGC and used it without any attenuation?
The Airspy is good for a relatively cheap SDR but it has it's limits.

73 Alan G4ZFQ


 


Alan
 

some details can be found here:
https://www.ab4oj.com/test/main.html#NPR
Andy,

Thanks, all I could find was "National Public Radio"!

Alan


Zacharias Liangas
 

>Are you saying you turned off the AGC and used it without any attenuation?
Just think that my ICOM R75 never overloads . this is a term of high dynamic range or NPR  .
If supposedly Airspy has a dynamic range of 110db BDR  as stated in its web  page , 10 db more than mine's ICOM R75 , simple logic advises Youself's numbers are wrong . Unless my philosophy is old fashioned
I don't know what happens to the ELADS2/FDM  in such cases.
As in example the 50 m band on mid nights (18z) is flooded with 6 powerhouses of -45 dbm signals on SDRconsole  or -15dbFS as stated in Sharp hat cause the overloading . I  live in Thessaloniki

>The Airspy is good for a relatively cheap SDR but it has it's limits.
In practice Airspy performs  as my stadalone radios , much better  than the RSP1a in the lower bands


Clint Chron
 

Here is a drill down on Adam’s Web page for the article that discusses NPR:

 

https://www.ab4oj.com/test/docs/npr_test.pdf

 

73

Clint

W7KEC

 

From: EladSDR@groups.io [mailto:EladSDR@groups.io] On Behalf Of Zacharias Liangas via groups.io
Sent: Wednesday, April 29, 2020 2:46 AM
To: EladSDR@groups.io
Subject: Re: [EladSDR] NPR and Dynamic Range question

 

Noise power ratio


Tudor Vedeanu
 

Zacharias,

On the Airspy you must leave AGC on if you want the best dynamic range and avoid overloadIng. If you turn off the AGC, then you must adjust the attenuation manually in order to avoid overloading and intermodulation.

Tudor