I watched the waterfall on my SDR when I was testing my AllStarNode, and I realized that both my cheap chinese HT and the crappy chinese HT I used to make the node have spurs all up and down the place. 😬
I don't have any real test equipment to quantify it, but it looks kinda nasty from my unscientific tests.
[#]HamRadio #AllStarLink #AmateurRadio
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@brainofdane
This might be that "infinite" spectrum stuff they're talking about with FM/PM/GMFK/4FSK/...
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@brainofdane Beware that if the signal into the SDR is too powerful, then you will also see spurs generated in the mixer in the SDR.
If you move the HT away from the SDR the main signal should drop in amplitude. If the spurs come from the HT, then they should drop at the same rate as the main signal. If they come from the SDR front end, then the spurs will drop quicker than the main signal.
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@brainofdane Other ways to attenuate the signal is to collapse the antenna (if you have one of the whip antennas), to add an attenuator in line between the antenna and the SDR, or to to use polarization - reorient the transmitting and receiving antenna so that they are perpendicular to each other (eg. one vertical and one horizontal).
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@raek these are some great tips. I hadn’t put much thought into it, but I need to do a few tests to understand what I’m seeing. I don’t have an oscilloscope or any other spectrum analysis equipment, so I’m just making casual observations.
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