It's all about the Software

Hi,

I notice a bug with RFspace SDR-IQ, it was tested with 2 different SDR-IQ, same result.
There is always a strong carrier on the center of spectrum:
I attached 2 screenshot where i swap the center FRQ between 1.850 and 1.875.

73
Pat
ON4AMI / OO7P

That is what is known as a DC Spike, more info here:

viewtopic.php?t=978

If running an SDR-iq locally, SDRC will make it go away with time. But for some reason, running and SDR-iq via a server (Like I run all of my 13 SDR's I have on 5 servers) on large bandwidths, it does NOT slowly decay. One has to learn to hit the right mouse button and shift the desired operating frequency either side of center when using the SDR-iq.
I'm on my KA1GJU@PCARC server right now for a quick test with an SDR-iq, and on 30kHz bandwidth, SDRC slowly takes the spike 0, as well as on 40kHz. On higher operating bandwidths, it does not go away. Not sure if it's something Simon overlooked or what. I've mentioned it before, but he has much bigger fish to fry. lol

73 Kriss KA1GJU

This happens naturally. The first main reason is A/D converter imbalances and phase differences. Some samplers are very good (double rate on one A/D) and some are not so good. This can be balanced out through various techniques. The second main reason is simple physics you cannot avoid, self-conversion of phase noise on the various local oscillators in the machine. You can sometimes bury it with additional gain on the front end. Certainly at HF it should get totally buried by noise coming in from all but tiny unamplified loop antennas.

I always tune stations I want to listen to off to one side or the other of exact center frequency.

{^_^}