My observation agrees with your point.
When my TV with Cable TV Box is operated, the reception by indoor antenna+dongle+Pi located in same room dropped considerably, and when the TV + Cable TV box were turned off, the reception boosted.
I then moved the indoor antenna+dongle+Pi to adjuscent room, and the influence of noise from TV/CableTV Box reduced considerably, as shown by marked improvement in reception even when TV/CableTV Box were operating.
Please - I am not making fun, judging, or critisizing recent generations. Of course I admit my thinking is out-of-date; obsolete.
Let me explain - when the USA prided itself of being a major technology & manufactuing power, “precision-of-speech” and concise use of language; terminology, etc., had value.
Our use in the real world of aviation of ADS-B is an important safety tool. Hardly a flight is completed without me being shocked at how many aircraft passing close to mine, are not seen visually - but thanks to ADS-B, both ATC, others, & myself are able to manage our activities efficiently and safety.
Of course I appreciate real aviation, for any number of good reasons, isn’t for everyone. If folks who are not involved or even interested in aviation feel they want to know who is using the public’s airspace; to see what my airplane is doing, and where others and I am going, I see no harm - “each to his own” - I am not about to critisize other’s entertainment.
So again, you who are products (“victims”…? ) of modern education…i.e. you do not see that the title of this site “FLIGHT AWARE” means anything but what you personally want it to mean… are much more “in step” with modern culture than I am.
Actually, as others have pointed out, it’s not necessarily about aviation, it is about a lot of other things like: software defined radio, operating systems (eg Linux), software in general, networks, DSP, radio, antennas, etc. Just watching planes on a map is kind of like watching paint dry. Related, some people watch ships on a map. That’s like watching paint that has already dried.
I am reminded of when I was a Ham (a long time ago in high school). You could think of Ham radio as getting on the air and communicating other Hams. However, a lot of Hams I knew just built stuff (a rig) and were hardly ever on the air. So there’s different reasons why people get in to these hobbies.
David, about your antenna location, rather than moving the antenna, remount the antenna stick lower until 4 or more inches below the metal brace at the top. Should be much easier. Mount with crossed zip ties to start and find the best location. Have fun!
Maybe the above guesses on shielding interference are a factor. My stats and overall range look better with the plate in my attic. I will be leaving it up there and maybe doing a pizza plate addition at a later date. Already hot up there, and the RTLSDR LNA at the base of the antenna is quite warm. Some heat sinks will be finding their way up there soon.
Afternoon, little late in posting this… But have made some changes so thought I would update.
I have replaced the top ground shield, with one that’s a little more “complete” Hopefull its making better electrical contact. I have also add a “RF Sheild” around the Pi, just to try reduce any noise form that
I have had it running overnight, and here are the initial observations.
Seem there is now less of a gap between the dumber of detection and the number detected with a position. (white line is the time is started the change)
Range seem unchanged:
Noise seem lower:
Message rate seem noticeably higher:
I will run if for a week and see if the average number of detections over the week has been affected…
Who unlocked the dark ages box again.
Pretty sure Noone goes to BBC because they have an interest in the acronym BBC or the subject of broadcasting either.
Websites have ‘about’ pages so people don’t read the name as face value of the entire subject matter.
Check them out sometime.
My ideal antenna would be mounted on a gimble and have perfect (i.e. 0) gain, actively looking for signals 24/7 lol!
Alas, I don’t think one exists.
An antenna with a gain of 0 would be almost useless. You should target a much higher gain 
I installed ground planes on both the attic antenna and the interior window antenna. Nothing fancy, and probably not ideal as both are foil on cardboard with decent metal connections above the N connectors. Just a note, my receiver’s/pi’s are not under the antenna, and are 20 and 5 feet away from the antennas.
Results are good. Average Max Range has increased by 25 miles, to about 247 or so. Messages and planes counts are higher also, though within the variations we all see every day. Only time will tell.
It cost nothing to make the changes. Perhaps others can try similar tests to see if it affects their system performance. Positive or negative, let us know.
Depends on your reference.
0 dBi is not the same as dBd etc.
@victorbravo77 has obviously mentioned 0 gain in dBd, which is 2.15 when expressed in dBi.
@foxhunter :
dBi and dBd are used to measure the gain of antennas. Most sellers specify antennas in dBi for obvious commercial reason that it gives a higher numeric value (+2.15) for same antenna.
dBi is a measurement that compares the gain of an antenna with respect to an isotropic radiator (a theoretical antenna that disperses RF energy evenly over the surface of an imaginary sphere.)
dBd compares the gain of an antenna to the gain of a reference dipole antenna (defined as 2.15 dBi gain).
To convert dBi to dBd:
Thanks
So nobody is right or wrong without knowing the parameter
Correct. I could have been clearer. Old ham-speak.
I wonder if that dipole antenna pattern null when an aircraft is directly overhead is what causes the signal to be lost rather than too strong a signal. The antenna also has very low gain when the aircraft is near vertical (closest to the receive site). It’s usually assumed the signal is too strong rather than too weak when an aircraft is nearest to the receive site.
The signal strength goes by the square of the distance. Half the distance means 4 times stronger signals (6db more). The ellipsoidal shaped vertical antenna signal pattern goes by the cosine squared of the relative angle between the ground and the source position. Those two compensate somewhat, but the distance factor is the more significant in causing problems. That is, local planes will mess up reception before signal loss of the antenna has any effect.
Since the planes never stay directly above us for long, the hundreds of ADSB watts easily overwhelms the receivers. Unless you live under the takeoff/landing pattern of your local airport, it should not be a large factor for your reception. I get dotted lines on SkyAware when local Naval helicopter and small engine training flights fly nearby. I turned off adaptive gain functions, as those are intended for consistent transmissions like TV, and not pulse based ADSB.
My bad. Trying to get my “mean-median” signal as close to zero as I can, if that makes sense. Then I’ll just be about average.
As noted by someone else above (@abcd567), dBi compared with, say, dBFS.
I would expend some effort seeing source of noise, and if the noise level could be reduced much lower.
That pattern (with the very deep null) is very much a theoretical perfect antenna in free space (good luck achieving that!!).
A real antenna mounted on a real mast/roof/etc. doesn’t come close. All sorts of things distort the pattern (the antenna conductor is not infinitely thin, loading and matching are not perfect, reflections etc.). The result is the null is not as deep as predicted.
Added to that, when a plane is closest (directly overhead), it’s only a few thousand feet away and unobstructed (to an outdoor antenna) LOS, so even a deep null wouldn’t prevent reception.
Those should not have that much impact as long as it is not a full forest around you. Mountains (even more far away are impacting the range significantly more.
This is my range (on my Airsquitter) and the gaps are caused by mountains, partially miles away. I have roofs in the neighborhood which are higher than my antenna (including my own roof), but the impact is almost zero
