I have an RPi2, successfully running PiAware for the last 48 hours.
Running a collinear wire antenna - based on this martybugs.net/wireless/collinear.cgi (tuned to 1090) - on c12ft of 75ohm coax.
Antenna is currently positioned in front of a 2nd floor, double glazed window.
Currently running 75ohm coax, in the belief that the better quality coax, less signal / SNR issues.
Although the antenna is mounted c10ft away from the RPi2, the RPi2 itself is running off a wired (RJ45) connection direct into my wifi router. The Rpi sits c5ft away and down from the router.
Yesterday (1st full day) the systems seen c1600 air craft with c67,000 track points.
Looking at the heat map / compass, these signals are strongest W/NNW, which I assume (ok, so I haven’t checked! ) is the direction the window is facing (presumably becuase glass offers less “block” than the solid walls in that direction).
Ultimately, would like to mount the antenna on the “crest” (?) of the roof line, but before I get into the expense of someone getting up there - and grounding it etc, I see a lot of people here have had great results by mounting it in the attic.
So, my questions are this…
Does the proximity of the router (2g /5g) make any difference? Im assuming not as wifi’s on a different frequency.
I hear that an “Ohm mis-match” between the 75ohm coax and the 50ohm usb dongle can impact dB, <1dB. Should I use 50ohm, does the drop in quality to 50ohm coax outweigh the ohm mismatch?
I understand ADSB needs line of site, can I assume that slate roof offers less “block” than solid wall? I assume that rather than having “good” reception in one line of site (i.e through the glass window), moving the antenna to the center of the attic would give wider reception (near 360 degree), but weaker - as slate is still more of a block than glass?
To run the antenna to the attic, I’m going to need c40 ft plus of coax (50ohm), to get it from the RPi in my home office, up the wall and across to the center of the attic. Is this run of coax going to cause an issue? NB - I should be able to mount the RPi nearer the ceiling to reduce the cable run.
So - bottom line - should I move it to the attic?