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

[Helmut, DC6NY]

Hi Kjell,  

yes it seems strange, but the issue really exists inside the linear
operation range of the ADC. BTW, the test source was a low-noise 0dBm x-tal
oscillator on 50,500 Mc plus a variable 60 dB Weinschel attenuator.
Ok, I'm just waiting for some components for the EER project, so I'll have
time for some further tests this weekend with HERMES (v.2.0) and Doug's
latest PowerSDR.

73, Helmut

 
-----Ursprüngliche Nachricht-----
Von: hpsdr-bounces at lists.openhpsdr.org
[mailto:hpsdr-bounces at lists.openhpsdr.org] Im Auftrag von Kjell Karlsen
Gesendet: Samstag, 15. Dezember 2012 11:35
An: hpsdr at lists.openhpsdr.org
Betreff: Re: [hpsdr] strong signal performance for HERMES +ANAN-10

***** High Performance Software Defined Radio Discussion List *****

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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