Hey guys. My Lime seems to be pretty useless at the moment. I ran it outside yesterday over about 6 hours from 4-10 as the sun set. I was hoping to at least notice a change in intensity in any frequency band. I’m using a waveguide that’s tuned to 1.3 GHz, but I feel like there’s no real difference in results when I use that, the stock monopoles, or no antenna.
I used QSpectrumAnalyzer to do a large sweep over 1.2 GHz to 2 GHz just to try notice any changes, but I got nothing. Then I ran it again from inside and got the exact same plot. Here’s my plot, it hit an error after 4 hours and stopped, so I restarted it and patched it together in paint (not the most technical, I know).
Okay, nevermind that comment about the antennas making a difference, here’s a little comparison between the stock monopole, the waveguide I’m using, and no antenna at all.
You need good gain antenna and LNA in front of LimeSDR for that.
So add parabolic reflector of at last 3-4 m in front of that wave guide and LNA4ALL,
than please report here again…
Alright, so the LNA of the Lime isn’t enough. Sure sure, thanks for the heads up. I probably should’ve gone for a cheaper SDR and an external LNA, but suppose I’ll keep that in mind next time.
While I have you, any idea what those signals at around 1.8-2 GHz would be? Maybe cell signals?
For the Hydrogen line it will be centred on 1420MHz with some Doppler smearing to either side (Sol rotation combined with earth rotation+orbital shifts).
You probably want to filter ~100MHz on either side with either a bandpass filter or a set of low pass and high pass filters tuned for that window.
And the LNA, put it before the filters for best results.
