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Linrad + SDR-IQ. Please help
- Subject: Linrad + SDR-IQ. Please help
- From: "Gabriel - EA6VQ" <vhfdx.net; ea6vq.1@xxxxxxxxxxxxxxxx>
- Date: Sun, 20 Jan 2008 16:29:16 -0000
Yesterday I made the first test with Linrad and the SDR-IQ, trying to
receive JT65B EME signals on 144 MHZ, using an SSB-Electronics 144 MHz
downconverter. My intention was to compare the performance of this setup
with my usual receiver (TS-790), so I was receiving in parallel with both
rigs and using two separate computers. The computer running Linrad 2.35 has
a 2x2.4 GHz processor and 2 GB of memory, and it's running Windows XP.
The results with Linrad and the SDR-IQ were absolutely disappointing, but
I'm sure that it must be because I have wrongly configured something, so I
will appreciate your help.
I have noticed three major problems:
1.- The signal repeatedly seems to drop for some seconds and then return to
the normal level. I looks like if someone was switching on and off the
preamplifier all the time. This does not happen with SpectraVue or WinRad,
so I don't think it's a problem of the SDR-IQ. You can see a screenshot of
this effect at http://www.vhfdx.net/temp/lines_linrad.jpg
2.- Signals are drifting up. In the baseband waterfall I can see how all
signals I receive are always drifting up. The same signals received with the
TS-790 were absolutely stable.
3.- Signals in the middle of the receiver bandwidth are noticeably stronger
that near the edges. You can also see this effect in the screenshot at
I used M_CIC2 , M_CIC5 , M_RCF , OL_RCF . You have the Linrad
configuration files I used at http://www.vhfdx.net/temp/linrad_parms.zip
Many thanks & 73. Gabriel - EA6VQ
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