WingbitsMy wingbits antenna has been working great for a week since receiving the MGW310. But recently after monitoring the graph1090, I noticed some serious signal dropout and db gain loss. Normally it would run steady 39 to 42 db straight line. But the last day I had a serious dropout where the signal dropped down to 9 to 24DB and you could see the loss of coverage in aircraft. The GEODNET seemed unaffected. No internet issues and no voltage issues.
I rebooted the unit and it did not fix the problem. I waited and with time the signal came back up to 42db and was steady straight line for hours. I am getting an occasional dropoff down to 28 db then it recovers back to a steady 39 db or 42db. Then recently it dropped off 12 to 24 db for about 20 minutes before recovering.
What’s causing this? I’m in south texas and we are hot here. I check temp and my unit is 55 to 60 Deg C at night and 65 to 75 Deg C during the day. These dropouts were on a cloudy day. temps were 60 to 70 range. cable connection and antenna are screwed on tight. Caps not removed from unused connectors.
eye4detail...
Ok. I figured it out. There is automatic gain control on this antenna. I just so happen to be in an area of Student pilots practicing the approach. So, on occasion, when aircraft fly directly overhead or nearby within 1000 feet, the signal from the aircraft is so strong that the antenna receiver has to attenuate the signal to prevent overload. At that moment I lose half my aircraft tracking or those farther than 100nm.
As soon at the aircraft passes, it takes a few minutes but eventually the gain is increased again. I did this by the two charts. I watched the local aircraft fly by and the RSSI increase to almost -1.0 db. at this point if the signal grew, I would see the antenna db gain drop and watch my aircraft fall off the list. When the plane went away the signal would slowly grow back.
Therefore any signal nearby that is on the same frequency and is seen as very loud by the antenna receiver causes attenuation. I am watching right now as the aircraft flew right over my antenna. less than 1000 feet. the RSSI remains -1.5 db or less less than 1 mile. I watch as my list of observed aircraft drops from 50 down to 25. Gain dropped from 42 down to 20 db and its hovering there while that aircraft is flying the pattern.
With ADS-B I can see the signal strength and distance to the aircraft that is causing the problem. I don’t think I can see other signals similar to this frequency that could cause this interference(noise). I can see it when it happens, but historically it’s difficult to determine.
Would be nice if there were a detailed hackers breakdown of stuff like this. How it works, not just the 30,000 foot view. But detailed operation like this.I haven’t seen it. Maybe its in the BYOD section. I haven’t seen it or looked much over there. The graphs1090 and tar1090 is very valuable analytical data and are now my goto charts.