[hpsdr] strong signal performance for HERMES +ANAN-10

[Kjell Karlsen]

Hi Helmut.

What you see is really strange. If I test with my Signal Generator and  
inject a signal at -11.4 dBm (that is 0.5 dB less than what gives ADC  
Overload), I see a rise in noise level at +- 5 KHz up to -117 dBm due to  
the sideband noise of the generator. In addition I see some spurs > -100  
dBc.

At -70 dBm there are NO spurs at all! All tested with Hermes.

73, Kjell




På Sat, 15 Dec 2012 10:34:01 +0100, skrev Helmut, DC6NY <dc6ny at gmx.de>:

> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi Eric and Peter,
>
> I can confirm your observations: the spurs are only 60 dB down and
> symmetrically to the wanted signal. Distance between spurs and/or wanted
> carrier is twice the selected sampling rate of base band: 2 x 48 kc  or  
> 2 x
> 96 kc or 2 x 192 kc.
>
> 73, Helmut, DC6NY
>
> -----Ursprüngliche Nachricht-----
> Von: hpsdr-bounces at lists.openhpsdr.org
> [mailto:hpsdr-bounces at lists.openhpsdr.org] Im Auftrag von Peter n Di
> Gesendet: Samstag, 15. Dezember 2012 06:58
> An: 'E van Maanen'; hpsdr at lists.openhpsdr.org
> Betreff: Re: [hpsdr] strong signal performance for HERMES +ANAN-10
>
> ***** High Performance Software Defined Radio Discussion List *****
>
> Thank Eric,
> 	Rushed up to the shack when your email arrived and tied enabling
> 'dithering' in powersdr but it seemed to make no improvement to the  
> multiple
> signals from the local 50 Mhz beacon.
>
>> Peter,
>> If you use powerSDR, check if dithering is enabled.
>> I had the impression that hermes was not that good at all when I tested  
>> it
> for the first time until I doiscovered that dithering is off >by default.
> Specially with strong constant carrier signals dithering is essential to
> obtain sufficient linearity.
>> 73
>> Erik PA3DES
>
> On powersdr the beacon shows as -67dBm or about S9+20 signal and many of  
> the
> products shown on the display measure at S1-S5 depending on where they  
> are,
> which should be easily seen on my 'real radio' but they do not show up.
>
> There is no Noise blanker, ANL or other options turned on and the ATTen  
> is
> set to zero, so I am at a loss to move forward. It would seem to be a  
> case
> that I have to stick with a 'real radio' on 50MHz.  The antenna is a M2 9
> element, have tried it at various azimuths and still see the products.
>
> Regards,
> Peter, vk5pj
>
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