What exactly does this dump1090 graph show?


#1

Hi all,

Bit of a FUBAR last night…

My amp and PSU turned up, so I thought I’d quickly splice them into the main antenna feed using f connectors and bnc’s (BNC’s to the reciever pigtail and ant - I already had these in use).

Anyway, did a pretty good job on the f-connectors (screw on - nice n easy), but when it came to the BNC’s, the coax was too thick to take them…

In desperation I used chocolate strip to connect the dialectic and shielding (copper hair-wire? - is that called sheilding, as well as the foil?), between two different gauges of coax, splicing the BNC’s onto the end of the proper cat 6…

YUCK! :wink:

All sorts of bad… lol

Surprisingly, this actually worked.

Now, looking at my dump1090 stats, we’re seeing all the expected negative impacts…

https://docs.google.com/drawings/d/1N7B5EQw7e6ijE4cWIimA8gdcQXKuOBuyTHVjWrmaDxY/pub?w=960&h=720

The interesting thing is - as I read it (bearing in mind im color blind!) is that “Noise level” seems a lot flatter than it did before, at least initially (wednesday).

Bearing in mind I’m not currently using a filter (just inline amp and PSU) - what does this imply / show?

So, all in - I’m surprised my bodge last night works at all, and full expected it to have a negative impact.
I’m currently using old spares and cludges till my new stuff (wf100, preamp/filter, proper connectors etc), so I’m not particularly worried.

Just interested… :slight_smile:


#2

The noise level includes power from damaged/overlapping messages and EMI not merely thermal noise. If you have a poor antenna connection then both the signal and noise levels will be reduced. If the noise level drops below the minimum sensitivity level of the dongle then it’ll “flatten out”.

(also I don’t think you mean dielectric - the dielectric is the material between the center core and the foil/braid shield¸ often foam, sometimes another material or air; it is one of the things that determines the impedance of the cable)


#3

Thanks Obj - learn something new every day! :slight_smile: