freddoair
New Member
A while back I read a question about a particular ADS-B filter that was on Ebay, so I took a look https://www.ebay.com/itm/132406298935?ul_noapp=true
Given that the filter was from Mini Circuits, a long established and well respected US manufacturer of microwave components, and the price was quite reasonable - even with freight to Australia, and a not so favourable exchange rate - I took a punt and bought one. This is a bandpass filter for ADS-B, and insertion loss is respectable at about 2.0 - 2.5dB. It's a lot more convenient from a mounting perspective than the coaxial cavity filter I was building!
My RPi and DTV dongle have lived in a weatherproof enclosure directly under the antenna for about 18 months, and the antenna directly fed the dongle input via 600mm of RG214 (double screened RG213) coax (and a short adaptor cable). Apart from a not-so-nearby lightning strike killing the original dongle (it took three weeks to finally die) after nearly a year in service, the installation has worked well.
Today, I relocated the RPi and dongle to the shed, and mounted the MiniCircuits filter and a LNA4ALL pre-amp in the weatherproof box under the antenna. I have about 6m of RG213 coax between the mast head unit and the RPi/dongle, it's loss being of no consequence given the gain and noise figure of the pre-amp. As is said, the proof is in the eating, so ......
A few hours of uptime has returned around 60% increase in the number of planes observed, due to a significant improvement in system noise figure. I normally send about 2,000,000 packets to Plane Finder each day. After just three hours today I've sent 1,600,000 and I'm keen to see what the total is tomorrow. Aircraft on approach to a nearby (45km away) airport used to disappear at about 900-1100 ft. Today I see them down to about 600ft. Now I can't wait to get the antenna from 4m above ground, to about 7.5m to increase path clearance for the S to NW sector. Sorry about the mixed units, I tend to work in both.
Even though it's early days (hours, even) I consider the MiniCircuits filter/LNA4ALL pre-amp combination a great asset to my ADS-B installation.
Ray
Given that the filter was from Mini Circuits, a long established and well respected US manufacturer of microwave components, and the price was quite reasonable - even with freight to Australia, and a not so favourable exchange rate - I took a punt and bought one. This is a bandpass filter for ADS-B, and insertion loss is respectable at about 2.0 - 2.5dB. It's a lot more convenient from a mounting perspective than the coaxial cavity filter I was building!
My RPi and DTV dongle have lived in a weatherproof enclosure directly under the antenna for about 18 months, and the antenna directly fed the dongle input via 600mm of RG214 (double screened RG213) coax (and a short adaptor cable). Apart from a not-so-nearby lightning strike killing the original dongle (it took three weeks to finally die) after nearly a year in service, the installation has worked well.
Today, I relocated the RPi and dongle to the shed, and mounted the MiniCircuits filter and a LNA4ALL pre-amp in the weatherproof box under the antenna. I have about 6m of RG213 coax between the mast head unit and the RPi/dongle, it's loss being of no consequence given the gain and noise figure of the pre-amp. As is said, the proof is in the eating, so ......
A few hours of uptime has returned around 60% increase in the number of planes observed, due to a significant improvement in system noise figure. I normally send about 2,000,000 packets to Plane Finder each day. After just three hours today I've sent 1,600,000 and I'm keen to see what the total is tomorrow. Aircraft on approach to a nearby (45km away) airport used to disappear at about 900-1100 ft. Today I see them down to about 600ft. Now I can't wait to get the antenna from 4m above ground, to about 7.5m to increase path clearance for the S to NW sector. Sorry about the mixed units, I tend to work in both.
Even though it's early days (hours, even) I consider the MiniCircuits filter/LNA4ALL pre-amp combination a great asset to my ADS-B installation.
Ray