Thanks Malcom,
I got a couple of the noolec RTL T820 little green receivers and put them at the end of 5m powered usb extension cables, see image attached.
They work very good with HDSR and RTL1090 ADS-b software, see and hear lots of aircraft message
http://www.nooelec.com/store/sdr/sdr...832-r820t.html
The attached images are of my portable (small)equipment.
The noise levels a around 110db.
The image with the air traffic shows a short burst level change, not from the air traffic. I am suspecting a meteor but not yet proven.
Also , seeing these converging and diverging signals when out side, some short and long cross overs.
Would be interested to hear if others can get these variations from better equipmnet.