As the subject line suggests I added one of the Nooelec filters/LNA to my setup (all within a vented weatherproof box 10’ beneath DPS ADSB antenna/LM240 cable). The filter/amp is powered by a USB port off the POE hat added to an RPi 4. It works well increasing range, planes. I also swapped out the blue dongle for an orange (so no duplicate 1090 filter).
Question is should I (in theory) set the gain on the dongle to 0.0 as the Nolelec should be handling all the gain?
Should I try turning on the adaptive gain and go from 0.0 to xx.xx as min/max?
I am interested in what you find out as I just added the same device. I went from 32.8 to 16.6 on my (Radarbox green) dongle gain. I am still trying to figure out the optimal point. I should note I was using a Uputronics LNA below before.
I had no luck with my sawbird +, in addition the connectors were mislabeled which made things confusing. It seemed to hurt my range… but that said most of my receive sites are co-located with things like cellular sites, FM radio, TV transmitters, etc… so not the quietest RF environment, I think I simply overloaded the receiver with too much noise. I’m still trying to move up the site list, just got to #6 with my newest receiver, but I am still always trying to improve! I thought the sawbird would be the magic bullet… nope.
I have found that my weak signals are really suffering. I am not sure if that is just cause the LNA has a lot of gain or that it is really hurting anything. The gain is at 16.6 but my logging shows that a gain or about 8.7 gives me a much wider signal range. Here is my graph with 16.6 …
Summary…I made several tests using the SAWbird+ and a Nooelec SDR dongle, SAWbird+ and orange FA, SAWbird+ and blue FA. The autogain function (I think) didn’t handle any of these combinations well and would seem to reset something in either the software or perhaps the SAWbird itself but the messages and planes would go to almost zero. I would reset things and it would work again, with good range and planes but alas, whatever settings were there would expire overnight. I suspect possible it could be the USB output from the POE hat I’m using may be freaking out somehow. The RPi 4 seems to be ok, not rebooting etc. Back to standard hardware it seems to be ok.
Cooling off outside now so puttering around up in the roof will be limited but I’m going to build a duplicate setup on the bench to more uniformly test what’s going on. Eventually, I could dedicate the second unit to 978 coverage (likely very little however in upstate NY).
My SAWBird+ is rock solid. I am using the green RadarBox dongle. It has improved my range and I now get over 400 km / 240 miles on occasion. I live in a very urban area and buildings are an issue. Overall … it is a good addition to my setup.
Like I said above, I’m not done with it, not yet. I may try to power the SAWbird from the RPi USB ports itself. It’s one thing I didn’t try while it was up on the roof.
