New install of the Discovery Dish with the L-band weather satellite LNA. So far no signal detected from GOES 16. I made the following measurements for tech support and awaiting further instructions:
Using a USB power meter the RTL V3 without feed attached voltage shows 4.943vdc, 0.150A, 0.743W.
With the feed attached: 4.895-4.919vdc varying, 0.150A, 0.735-0.742W varying.
With the bias-tee enabled: 4.716-4.724vdc, 0.389A, 1.840-1.859W
Still no signal detection shown in the spectrum and waterfall in Satdump.
Have not made any measurements at the LNA without approval.
The current draw is a bit higher than expected, which is a little odd, but often USB current meters have inaccurate readings so it could be ok.
If you have AGC’s turned on, make sure to turn them off. With the AGCs on, you won’t notice any difference in the noise floor as the AGC will compensate for the feeds gain.
Post a screenshot of your SatDump settings so we can check it.
I tried a lot of different setting combos in Satdump, only change was in the noise floor. Spectrum/Waterfall was not showing any signals either. Gain was set to Max manually. Installed SdrSharp to see what could be found on there, I could hear audible noise and there was and clicked on a spike at the upper end of the spectrum which was just a faint steady tone. I don’t have a live screen shot as I received an email yesterday to return the LNA and I repackaged it, but here is a screen shot of my settings:
I built my own GOES station back in the 90s with a 10 foot dish and a coffee can feedhorn with LNA, used it for WEFAX and EMWIN acquisition.
Waiting for a return ship label for now:
"It seems that the feed is drawing power, but maybe there is something else that is wrong. Could you please send it back to me? What is your shipping address? I’ll send you a label. "
If you still have it, I would suggest upping the samplerate to 2.4 MSPS or 2.56 MSPS. Satdump is a little picky, often it won’t decode at lower sample rates.
1.536 MSPS might be too small to cover it with the rolloff, and you also won’t be able to see the signal hump as the GOES signal is about 1.2 MHz and so it would cover most of the visible bandwidth and just look like noise.
Also, it’s possible that the FFT graph was just out of scale. If the scale is too big, then the signal won’t be easily visible because it will only be a few dB above the noise floor. You can compress the scale by playing with the FFT MAX and Min sliders.
Also not sure how accurate the dish was aimed, but I assume you had it aimed at the satellite, no obstructions, and had set the skew correctly? Often a little bit of trial and error with the aiming is required.
Thanks for your input. Syed had me ship the feed to him, so I have nothing to use for now. I tried various settings for two days, the last you see in the screen shot were ones I saw other people using which didn’t help either. Before the GOES 16 position shift I was using 131.3 magnetic AZ and 34.9 Elev. The 1694.1mhz setting only put a thin line down the middle of the waterfall. Changing FFT settings only turned the waterfall all one color with no signals embedded in it. I would think even a faint signal from GOES would show something in the spectrum and waterfall. But I could not replicate reception that others have demonstrated on Youtube.
Not sure what you are referring to in regards to “skew”, I did try vertical and horizontal poliarization of the LNA if that is what you mean. But no in-between rotations.
