Connected to my system today (after not looking at it for a while due to Christmas etc) and noticed my stats were way down. Checked my 2nd (reference) system, and it was the same. Looking back at the charts it seems that sometime around mid November my stats take a downward turn. I can’t be sure but it may coincide with an electrician doing some electrical work in the house (replacing main fuse board).
I have 2 RPi’s one with a Orange Flightaware dongle, and the other with a Airspy mini. They connect into a splitter which connects into a Bias tee power injector. Then near the aerial I have a RTL-SDR LNA (Amp) and then Flight Aware aerial. I checked all connections etc, and all look ok, so then start removing / isolating components such as the splitter, Bias tee power injector, LNA.
If I remove the power to the bias tee injector the message rate drops down to almost nothing, so that would indicate that the RTL-SDR LNA does need to be powered still. However when I removed the RTL-SDR LNA and replaced it temporary with the splitter (as that was the only thing I had to join the 2 ends of the cable together) it didn’t really seem to make much difference with the message rate (think I was getting about 1600). I then got my old uputronics LNA (That I wasn’t using at the areal as it has no Bias tee) and with a long extension lead powered it via USB, and message rate went up to over 2000.
So, I may be wrong, but it seems that there may be an issue with the RTL-SDR LNA, in that it needs to be powered still to “work”, however it may not be amplifying the signal anymore. Has anyone seen anything like this before?
I see that the RTL-SDR LNA is no longer available, and in another recent post on these forums it mentions Q1 or Q2 2003 for a new version, but that was a year ago and no sign yet.
I see that the current uputronics LNA can be powered by Bias tee, so that could be a possibility at the aerial now, though as it’s bigger then the RTL-SDR LNA not sure it will fit in the waterproof box I have on the wall.
Anyone with any stat comparisons of the uputronics vs the RTL-SDR LNA, or any other LNA’s worth looking at.
So I ordered one of these NooElec-SAWbird+ though expensive it was smaller than the uputronics one so I thought it would fit into the waterproof box better.
I have just swapped out the RTL-SDR LNA with it (fit was perfect), and so far things are looking better. With my old uputronics LNA down in the basement that I temporary connected up yesterday I was getting about 2200 messages, when I removed that it was about 1800-2000, then when I removed the RTL-SDR and fitted the SAWbird+ messages went up to about 2800 at first and have been about 2600-2700 since.
Can’t remember what the plane count was just before the change, maybe just under 200, but now its up to 220 - 230.
Hard to say if it’s back to how good it used to be, as stats were taking a downward trend because of winter, so will have to see over the next few days / week on the charts if they get back up to where they were mid Nov.
Yes, thanks, the system with the Airspy mini automatically almost straight away dropped down to about 13 which is around where it used to be pre mid November (had risen to about 20 when the issue started). The system with the flightaware stick I was already running the “sudo autogain1090” command, and so far its dropped down to 1.4 which is a bit below what is was pre Mid Nov (think that had risen to 16.6 during the issue).
So, it’s been just over a month, and all seems to be working ok still. My stats are back up, and my main system with the Airspy is back up to 25th in the UK, which is around where it used to be (think it used to be between about 20th and 25th in the summer months).
Yes, As soon as I got it I first added it before the dongle, and checked it worked (and saw an increase in messages / planes), so I then just installed it by the aerial, and it’s been there since.
Though outside about 3m away from the aerial it is in a waterproof box. When I removed the old LNA there was no sign of any water in the box, or on the LNA. As I mentioned, think the original one may have gone pop while an electrician was doing wiring work in the house. I feed bias-t via a 5v power injector, but that injector is plugged into a UPS, so if it was because of that not quite sure why it would have happened.
it was smaller than the uputronics one so I thought it would fit into the waterproof box better.