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

[richardh at iinet.net.au]

I have seen IM products generated between pagers near 144MHz.They were
colocated on a tower somewhere - these things had an EIRP of 1KW or
soWhen they were both transmitting there were various IM products
generated I managed to confirm that this was not IM in my receiver (a
HP 140 series spectrum analyser)by showing that they all varied by the
same amount as the main carriers with attenuation.It seems that
antennas close together and no diplexer can feed energy into the other
transmitter     Could something like this be happening here?
R 

----- Original Message -----
From: "Helmut DC6NY" 
To:"Peter n Di" , "E van Maanen" , 
Cc:
Sent:Sat, 15 Dec 2012 10:34:01 +0100
Subject:Re: [hpsdr] strong signal performance for HERMES +ANAN-10

 ***** 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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