Hi Janne, > Now, using Winrad, I can get solid -30..-35db image rejection. It > changes only few db across the whole spectrum of screen. I'm quite > happy about that, but this leads to the problem no 1. > > In Winrad, I still have to have the phase slider set to max value and > the delay tag pressed to get even this image rejection. Is this the > fault of the soundcard? I would not think so. You might reverse I and Q. If the phase slider wants to stay the same, the problem is the soundcard (or rather the device driver I would guess) but if you have to shift the phase slider to the opposite position, then the error would be in the radio hardware. > What I also noticed, is that I could get better attenuation for the > image with Powersdr, but only in a single spot. I dunno how these > softwares differ, but Winrad seems to work better in this. Still have > to study the linrad. > > >Oooh! I was referring to mirror image suppression and how it varies > >with signal frequency. The boxes in the upper corners of the > >waterfall can be used to thange the X-scale so you see the entire > >frequency range. > > Ok, I have to do this. Do you prefer the IQ calibration first, or is > the idea to see that what kind of image we have, without the calibration? Without calibration you will see the performance of the bare hardware (analog + digital) After calibration you should have 70 dB or better on all frequencies. Maybe thermal drift will degrade rapidly, but if you stabilize temperature and voltages you should be able to have 70 dB or better permanently.
73 Leif
